Room Temperature Polariton Condensation from Whispering Gallery Modes in CsPbBr3 Microplatelets

Room temperature (RT) polariton condensate holds exceptional promise for revolutionizing various fields of science and technology, encompassing optoelectronics devices to quantum information processing. Using perovskite materials, like all-inorganic cesium lead bromide (CsPbBr3) single crystal, provides additional advantages, such as ease of synthesis, cost-effectiveness, and compatibility with existing semiconductor technologies. In this work, the formation of whispering gallery modes (WGM) in CsPbBr3 single crystals with controlled geometry is shown, synthesized using a low-cost and efficient capillary bridge method. Through the implementation of microplatelets geometry, enhanced optical properties and performance are achieved due to the presence of sharp edges and a uniform surface, effectively avoiding non-radiative scattering losses caused by defects. This allows not only to observe strong light matter coupling and formation of whispering gallery polaritons, but also to demonstrate the onset of polariton condensation at RT. This investigation not only contributes to the advancement of the knowledge concerning the exceptional optical properties of perovskite-based polariton systems, but also unveils prospects for the exploration of WGM polariton condensation within the framework of a 3D perovskite-based platform, working at RT. The unique characteristics of polariton condensate, including low excitation thresholds and ultrafast dynamics, open up unique opportunities for advancements in photonics and optoelectronics devices.

Strongly enhanced light-matter coupling of monolayer WS2 from a bound state in the continuum

Exciton-polaritons derived from the strong light-matter interaction of an optical bound state in the continuum with an excitonic resonance can inherit an ultralong radiative lifetime and significant nonlinearities, but their realization in two-dimensional semiconductors remains challenging at room temperature. Here we show strong light-matter interaction enhancement and large exciton-polariton nonlinearities at room temperature by coupling monolayer tungsten disulfide excitons to a topologically protected bound state in the continuum moulded by a one-dimensional photonic crystal, and optimizing for the electric-field strength at the monolayer position through Bloch surface wave confinement. By a structured optimization approach, the coupling with the active material is maximized here in a fully open architecture, allowing to achieve a 100 meV photonic bandgap with the bound state in the continuum in a local energy minimum and a Rabi splitting of 70 meV, which results in very high cooperativity. Our architecture paves the way to a class of polariton devices based on topologically protected and highly interacting bound states in the continuum.

Rydberg polaritons in ReS2 crystals

Rhenium disulfide belongs to group VII transition metal dichalcogenides (TMDs) with attractive properties such as exceptionally high refractive index and remarkable oscillator strength, large in-plane birefringence, and good chemical stability. Unlike most other TMDs, the peculiar optical properties of rhenium disulfide persist from bulk to the monolayer, making this material potentially suitable for applications in optical devices. In this work, we demonstrate with unprecedented clarity the strong coupling between cavity modes and excited states, which results in a strong polariton interaction, showing the interest of these materials as a solid-state counterpart of Rydberg atomic systems. Moreover, we definitively clarify the nature of important spectral features, shedding light on some controversial aspects or incomplete interpretations and demonstrating that their origin is due to the interesting combination of the very high refractive index and the large oscillator strength expressed by these TMDs.

Managing Growth and Dimensionality of Quasi 2D Perovskite Single-Crystalline Flakes for Tunable Excitons Orientation

Hybrid perovskites are among the most promising materials for optoelectronic applications. Their 2D crystalline form is even more interesting since the alternating inorganic and organic layers naturally forge a multiple quantum-well structure, leading to the formation of stable excitonic resonances. Nevertheless, a controlled modulation of the quantum well width, which is defined by the number of inorganic layers (n) between two organic ones, is not trivial and represents the main synthetic challenge in the field. Here, a conceptually innovative approach to easily tune n in lead iodide perovskite single-crystalline flakes is presented. The judicious use of potassium iodide is found to modulate the supersaturation levels of the precursors solution without being part of the final products. This allows to obtain a fine tuning of the n value. The excellent optical quality of the as synthesized flakes guarantees an in-depth analysis by Fourier-space microscopy, revealing that the excitons orientation can be manipulated by modifying the number of inorganic layers. Excitonic out-of-plane component, indeed, is enhanced when "n" is increased. The combined advances in the synthesis and optical characterization fill in the picture of the exciton behavior in low-dimensional perovskite, paving the way to the design of materials with improved optoelectronic characteristics.

Tuning of the Berry curvature in 2D perovskite polaritons

The engineering of the energy dispersion of polaritons in microcavities through nanofabrication or through the exploitation of intrinsic material and cavity anisotropies has demonstrated many intriguing effects related to topology and emergent gauge fields such as the anomalous quantum Hall and Rashba effects. Here we show how we can obtain different Berry curvature distributions of polariton bands in a strongly coupled organic-inorganic two-dimensional perovskite single-crystal microcavity. The spatial anisotropy of the perovskite crystal combined with photonic spin-orbit coupling produce two Hamilton diabolical points in the dispersion. An external magnetic field breaks time-reversal symmetry owing to the exciton Zeeman splitting and lifts the degeneracy of the diabolical points. As a result, the bands possess non-zero integral Berry curvatures, which we directly measure by state tomography. In addition to the determination of the different Berry curvatures of the multimode microcavity dispersions, we can also modify the Berry curvature distribution, the so-called band geometry, within each band by tuning external parameters, such as temperature, magnetic field and sample thickness.

Adoption of patient-reported outcomes (PROs) in clinical practice for older patients receiving active anticancer treatment: Impact on health-related quality of life (QoL)

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Background: PROs are the gold standard to describe subjective symptoms. In order to improve clinical management of outpatients receiving active anti-cancer treatment at Medical Oncology, Mauriziano Hospital, Turin, Italy, in January 2018 we introduced in routine clinical practice an assessment of patient-reported symptoms and toxicities. We demonstrated that use of PROs in clinical practice was associated with a significant QoL improvement, compared to the traditional visit (Baratelli, Support Care Cancer 2019). In this secondary analysis, we show the results obtained in older pts ( > 70yrs). Methods: Eligible pts were receiving an active anti-cancer treatment, as outpatients. Pts treated in 2017 underwent “usual” visits (group A), while pts treated in 2018 before each visit received a paper questionnaire by a dedicated nurse, in order to provide information about symptoms and toxicities to be discussed during visit (group B). Primary objective was the comparison of QoL changes, measured by EORTC QLQ-C30. Results: Out of 211 pts, 88 were older than 70 yrs (47 group A, 41 group B). Median age was 76 (70-84 yrs). Most common tumors were colorectal (25.0%), lung (22.7%) and pancreatic (17.0%). 68.2% were receiving first-line treatment. Tumors and setting were similar between group A and B. Younger and older pts had comparable baseline QoL scores: mean global QoL score was 59.96 in younger pts vs. 57.39 in older pts. After 1 month, global QoL of older pts was significantly improved in group B compared to group A: mean change from baseline was -0.89 group A vs. +4.47 group B (p = 0.006, effect size 0.23). There were statistically significant differences in mean changes from baseline, in favor of group B, for role functioning (-5.67 group A and -0.81 group B, p = 0.034, effect size 0.20) and emotional functioning (-2.30 group A and +3.25 group B, p = 0.014, effect size 0.36). Mean changes from baseline for pain were significantly better for group B (-3.25) than group A (+6.03, p = 0.01, effect size 0.43). There were no significant differences between the 2 groups in terms of other functional scales or symptoms. There was no significant heterogeneity in the proportion of QoL responders between younger and older pts (p = 0.60). The proportion of older pts obtaining a clinically significant improvement in global QoL was numerically higher in group B (36.6%) compared to group A (19.1%, p = 0.09). Odds Ratio of obtaining an improvement in global QoL for group B vs group A was 1.73 (95%CI 0.75 – 3.99) in younger pts and 2.44 (95%CI 0.93 – 6.40) in older pts. Conclusions: This secondary analysis shows that the use of PROs in clinical practice, thanks to an active role of nurses and discussion of symptoms with physicians during the visit, is associated, also in older patients receiving active anticancer treatment, with a significant improvement in global QoL.

Improved Photostability in Fluorinated 2D Perovskite Single Crystals

Hybrid organic-inorganic perovskites are very promising semiconductors for many optoelectronic applications, although their extensive use is limited by their poor stability under environmental conditions. In this work, we synthesize two-dimensional perovskite single crystals and investigate their optical and structural evolution under continuous light irradiation. We found that the hydrophobic nature of the fluorinated component, together with the absence of grain boundary defects, lead to improved material stability thanks to the creation of a robust barrier that preserve the crystalline structure, hindering photo-degradation processes usually promoted by oxygen and moisture.

Aging of Self-Assembled Lead Halide Perovskite Nanocrystal Superlattices: Effects on Photoluminescence and Energy Transfer

Excitonic coupling, electronic coupling, and cooperative interactions in self-assembled lead halide perovskite nanocrystals were reported to give rise to a red-shifted collective emission peak with accelerated dynamics. Here we report that similar spectroscopic features could appear as a result of the nanocrystal reactivity within the self-assembled superlattices. This is demonstrated by studying CsPbBr₃ nanocrystal superlattices over time with room-temperature and cryogenic micro-photoluminescence spectroscopy, X-ray diffraction, and electron microscopy. It is shown that a gradual contraction of the superlattices and subsequent coalescence of the nanocrystals occurs over several days of keeping such structures under vacuum. As a result, a narrow, low-energy emission peak is observed at 4 K with a concomitant shortening of the photoluminescence lifetime due to the energy transfer between nanocrystals. When exposed to air, self-assembled CsPbBr₃ nanocrystals develop bulk-like CsPbBr₃ particles on top of the superlattices. At 4 K, these particles produce a distribution of narrow, low-energy emission peaks with short lifetimes and excitation fluence-dependent, oscillatory decays. Overall, the aging of CsPbBr₃ nanocrystal assemblies dramatically alters their emission properties and that should not be overlooked when studying collective optoelectronic phenomena nor confused with superfluorescence effects.

The role of PIAS3, p-STAT3 and ALR in colorectal cancer: new translational molecular features for an old disease

OBJECTIVE

Human colorectal cancer (CRC) is characterized by a sequence of biological events that determine its induction and progression. Gut microbiota has an important role in this multistep model of carcinogenesis, as well as constitutive activation of Signal Transducer and Activator Factors 3 (p-STAT3) and Protein Inhibitor of Activated STAT3 (PIAS3), which negatively controls STAT3. It has been reported that a liver growth factor, the Augmenter of Liver Regeneration (ALR), an anti-apoptotic, anti-metastatic factor, exerts protective/cell survival and anti-metastatic activities and has been detected highly expressed in neoplastic cells.

PATIENTS AND METHODS

To evaluate, by immunohistochemistry, p-STAT3, PIAS3 and ALR expression in neoplastic human tissues from CRC patients, grouping the data in accordance with the histological alterations (G1, G2 and G3) and metastasis presence. Western blot (WB) analysis of ALR was also determined in neoplastic and surrounding tissues. Finally, cell proliferation (Ki-67) and apoptosis (Bcl-2) were determined.

RESULTS

Colon cancer tissue samples showed: (1) ALR and p-STAT3 strongly over-expression in 100% of G1 tissue samples, reducing in G2 and G3 tissue samples; (2) PIAS3 immunological determination was poorly expressed in G1 tissue samples and highly expressed in the 100% of colorectal tissues from group G2 and G3. Ki-67 progressively increases with the importance of the anatomic-pathological alterations and Bcl-2 resulted higher in G3 tissue samples compared to G1 neoplastic tissues. WB data evidenced, in neoplastic tissues, compared to the tumour-surrounding tissues, ALR over-expressed in G1 neoplastic tissues and down-expressed in G3 neoplastic tissues.

CONCLUSIONS

Our data demonstrate a different dynamism of the investigated factors in relation to the severity of CRC histological findings. We hypothesize that the positive expression of ALR and p-STAT3 in the neoplastic tissue samples from CRC G1 group, associated to the absence of PIAS3, could be useful marker to identify an early stage of the disease. Based on these data and on our previous studies on gut microbiota in precancerous intestinal lesions, we are confident that, after microbial priming, a cascade of molecular events is started. So, the detectable molecules acting in these initial steps should be considered for the study of CRC progression and therapy.

Quantum hydrodynamics of a single particle

Semiconductor devices are strong competitors in the race for the development of quantum computational systems. In this work, we interface two semiconductor building blocks of different dimensionalities with complementary properties: (1) a quantum dot hosting a single exciton and acting as a nearly ideal single-photon emitter and (2) a quantum well in a 2D microcavity sustaining polaritons, which are known for their strong interactions and unique hydrodynamic properties, including ultrafast real-time monitoring of their propagation and phase mapping. In the present experiment, we can thus observe how the injected single particles propagate and evolve inside the microcavity, giving rise to hydrodynamic features typical of macroscopic systems despite their genuine intrinsic quantum nature. In the presence of a structural defect, we observe the celebrated quantum interference of a single particle that produces fringes reminiscent of wave propagation. While this behavior could be theoretically expected, our imaging of such an interference pattern, together with a measurement of antibunching, constitutes the first demonstration of spatial mapping of the self-interference of a single quantum particle impinging on an obstacle.

Quantum Nature of Light in Nonstoichiometric Bulk Perovskites

Sources of single photons are a fundamental brick in the development of quantum information technologies. Great efforts have been made so far in the realization of reliable, highly efficient, and on demand quantum sources that could show an easy integration with quantum devices. This has recently culminated in the use of solid state quantum dots as promising candidates for future sources of quantum technologies. However, some challenges, like their complex fabrication, random distribution, and difficult integrability with silicon technology, could hinder their broad application, making necessary the study of alternative systems. In this work, we clearly demonstrate single photon emission from quantum dots formed in nonstoichiometric bulk perovskites. Their simple growing procedures, exceptional stability under constant illumination, easy control of their optical properties, as well as ease of integrability make these materials very interesting candidates for the development of quantum light sources in the near-infrared.

Two-dimensional hybrid perovskites sustaining strong polariton interactions at room temperature

Polaritonic devices exploit the coherent coupling between excitonic and photonic degrees of freedom to perform highly nonlinear operations with low input powers. Most of the current results exploit excitons in epitaxially grown quantum wells and require low-temperature operation, while viable alternatives have yet to be found at room temperature. We show that large single-crystal flakes of two-dimensional layered perovskite are able to sustain strong polariton nonlinearities at room temperature without the need to be embedded in an optical cavity formed by highly reflecting mirrors. In particular, exciton-exciton interaction energies are shown to be spin dependent, remarkably similar to the ones known for inorganic quantum wells at cryogenic temperatures, and more than one order of magnitude larger than alternative room temperature polariton devices reported so far. Because of their easy fabrication, large dipolar oscillator strengths, and strong nonlinearities, these materials pave the way for realization of polariton devices at room temperature.

Clusterin serum level: how does it affect psoriatic patients?

Psoriasis is a chronic inflammatory skin disease with systemic involvement that might predispose to many psoriasis-related comorbidities, such as metabolic syndrome and cardiovascular disorders. Clusterin (Clu), also known as apolipoprotein J (ApoJ), is a highly conserved disulfide-linked heterodimeric glycoprotein implicated in a great variety of physiological and pathophysiological processes including lipid transportation, tissue remodeling, senescence, cell interaction, stress response, inflammation, apoptosis, diabetes mellitus and metabolic syndrome. Serum levels of Clu were assessed in 15 patients with moderate-to-severe psoriasis defined by the presence of a Psoriasis Area and a Severity Index (PASI) value of 10 or more. It was found that the Clu value was significantly higher in patients than in healthy subjects (p <0.001). Our data confirm that the association of psoriatic disease with some comorbidities, especially metabolic and cardiovascular disease, might support the correlation with increased circulating Clu. In particular, it should be pointed out that, according to the recent literature, the Clu could also have a protective role in the comorbidity of psoriasis patients. In addition, it has been published that Clu protects cardiomyocytes against ischemic cell death and is a potential therapeutic agent in the treatment of myocardial infarction; therefore it can be assumed that an artificial enhancement of Clu in the blood could limit the severity of damage also in respect to skin lesions. Although the increase in serum level of Clu was found in all patients with psoriasis, more studies on a larger cohort of patient samples is necessary to confirm the significance of high serum levels of clusterin/ApoJ and to suggest the use of this glycoprotein as an additional new marker in psoriasis pathogenesis. It could be a possibility to improve the prognosis in patients with psoriasis.

Sub-epitopic dissection of HCV E1315-328HRMAWDMMMNWSPT sequence by similarity analysis

Our labs are focused on identifying amino acid sequences having the ability to react specifically with the functional binding site of a complementary antibody. Our epitopic definition is based on the analysis of the similarity level of antigenic amino acid sequences to the host proteome. Here, the similarity profile to the human proteome of an HCV E1 immunodominant epitope, i.e. the HCV E1(315-328)HRMAWDMMMNWSPT sequence, led to i) characterizing the immunoreactive HCV E1 315-328 region as a sequence endowed with a low level of similarity to human proteins; ii) defining 2 contiguous immunodominant linear determinants respectively located at the NH(2) and COOH terminus of the conserved viral antigenic sequence. This study supports the hypothesis that low sequence similarity to the host's proteome modulates the pool of epitopic amino acid sequences in a viral antigen, and appears of potential value in defining immunogenic viral peptide sequences to be used in immunotherapeutic approaches for HCV treatment.

Intestinal permeability in patients with adverse reactions to food

BACKGROUND

An abnormal intestinal permeability could contribute to establish an altered sensitivity to food-allergen.

AIM

To evaluate the intestinal permeability in subjects with adverse reactions to food on allergen-free diet.

SUBJECTS

Twenty-one patients with food allergy and 20 with food hypersensitivity on allergen-free diet were enrolled and divided in four groups according to the seriousness of their referred clinical symptoms when they were on a free diet.

METHODS

Intestinal permeability was evaluated by Lactulose/Mannitol ratio urinary detection determined by anion-exchange chromatography.

RESULTS

Statistically significant different Lactulose/Mannitol ratio was evidenced in subjects with food allergy (p=0.003) or hypersensitivity (p=0.0008) compared to control patients. The correlation between Lactulose/Mannitol ratio and the seriousness of clinical symptoms, by using Spearman test, was statistically significant for food allergy (p=0.0195) and hypersensitivity (p=0.005) patients.

CONCLUSIONS

The present data demonstrate that impaired intestinal permeability, measured in our conditions, is present in all subjects with adverse reactions to food. In addition, for the first time, we report a statistically significant association between the severity of referred clinical symptoms and the increasing of Intestinal Permeability Index. These data reveal that intestinal permeability is not strictly dependent on IgE-mediated processes but could better be related to other mechanisms involved in early food sensitisation, as breast-feeding, or microbial environment that influence the development of oral tolerance in early infancy.

Mammalian augmenter of liver regeneration protein is a sulfhydryl oxidase

BACKGROUND

Augmenter of Liver Regeneration is an important secondary hepatic growth factor. Augmenter of liver regeneration protein has been shown to control mitochondrial gene expression and the lytic activity of liver-resident Natural Killer cells through the levels of interferon-gamma, but the precise enzymatic function of this protein is unknown.

AIMS

To define the enzymatic activity of augmenter of liver regeneration protein. The carboxy terminus of augmenter of liver regeneration protein contains a special CXXC motif characteristic for redox proteins and with faint homologies to the redox-active site of sulfhydryl oxidases. Tests were, therefore, carried out to establish whether isolated augmenter of liver regeneration protein can also function in the formation of sulfur bridges.

METHODS

Purified augmenter of liver regeneration proteins from rat and human were tested in enzyme assays for the ability to introduce disulfide bonds into protein substrates. The isolated proteins were tested for the formation of dimers and the presence of bound FAD was investigated spectroscopically. The function of the conserved CXXC motif was investigated by in vitro mutagenesis experiments and subsequent enzyme assays.

RESULTS

In this study, we demonstrate that rat and human augmenter of liver regeneration protein are flavin-linked sulfhydryl oxidases that catalyze the formation of disulfide bonds in reduced protein substrates. A flavin moiety is firmly but not covalently attached to the protein. In human cell cultures augmenter of liver regeneration protein is expressed in a long and short form that both exist as covalently linked dimers. The active site of the enzyme is associated with a conserved CXXC motif in the carboxy-terminal domain, that is present in the homologous proteins from yeast to humans and also in the human Q6 growth regulator protein. In vitro mutagenesis of one cysteine residue in the CXXC motif results in loss of enzymatic function and the mutated protein no longer binds FAD.

CONCLUSIONS

For the first time, these data assign an enzymatic activity to the important hepatic growth factor augmenter of liver regeneration protein. The finding that augmenter of liver regeneration protein acts as a FAD-linked sulfhydryl oxidase is essential to identify the molecular targets inside liver cells and to elucidate the precise role of mammalian augmenter of liver regeneration protein in hepatic cell growth, liver disease and regeneration.

The augmenter of liver regeneration induces mitochondrial gene expression in rat liver and enhances oxidative phosphorylation capacity of liver mitochondria

BACKGROUND

The mammalian augmenter of liver regeneration gene encodes a protein involved in the unique process of liver regeneration. The augmenter of liver regeneration respective protein stimulates hepatocyte proliferation in hepatectomized rats and inhibits cytotoxic activity of liver-derived Natural Killer cells from intact rats. Augmenter of liver regeneration protein shares homology with a Saccharomyces Cerevisiae protein essential for the viability, oxidative phosphorylation and cell-division cycle.

AIMS

To demonstrate if augmenter of liver regeneration protein, like the homologous in the yeast, plays a role in the regulation of biogenesis of mitochondria.

METHODS

Augmenter of liver regeneration protein was injected in intact rats and, in the hepatic tissue, the expression of two genes located in two different regions of the mitochondrial genome, mitochondrial ATPase 6/8, and ND1 subunit, and of a nuclear gene, mitochondrial Transcription Factor A, were considered. In addition, cytochrome content and oxidative phosphorylation capacity of liver-derived mitochondria were evaluated.

RESULTS

The augmenter of liver regeneration protein administration induces an increase in the mitochondrial gene expression and enhances cytochrome content and oxidative phosphorylation capacity of liver-derived mitochondria.

CONCLUSIONS

The present data demonstrate a comparable role in the regulation of mitochondria biogenesis in the eukaryotic cell like the yeast protein. This phenomenon could be part of the complex mechanism through which augmenter of liver regeneration regulates hepatocyte proliferation.

Molecular mechanisms of augmenter of liver regeneration as immunoregulator: its effect on interferon-gamma expression in rat liver

BACKGROUND

We have shown that the administration of exogenous Augmenter of Liver Regeneration protein in intact rats i) regulates mitochondrial gene expression by inducing the transcription and translation of the nuclear-encoded mitochondrial transcription factor A, and ii) inhibits the lytic activity of liver-resident Natural Killer cells.

AIMS

The present investigation was carried out to study the effect, in intact rats, of exogenous administration of Augmenter of Liver Regeneration protein on Interferon-gamma, a cytokine produced by activated Natural Killer cells and known to control the expression of mitochondrial transcription factor A, a nuclear gene responsible for mitochondrial metabolism.

METHODS

Interferon-gamma was measured as messenger RNA in liver-derived mononuclear leukocytes and as protein in liver-derived Natural Killer cells after a single injection of Augmenter of Liver Regeneration protein.

RESULTS

The data obtained demonstrate that: i) in intact rats, Augmenter of Liver Regeneration protein administration induces a reduction of Interferon-gamma in the liver-resident Natural Killer cells and ii) the administration of Interferon-gamma in 70% hepatectomized rats is followed by a significant reduction both of the mitochondrial transcription factor A expression and of liver regeneration.

CONCLUSIONS

These data demonstrate the pivotal role of Augmenter of Liver Regeneration as Growth Factor and as immunoregulator by controlling, through Interferon-gamma levels, the mitochondrial transcription factor A expression and the lytic activity of liver-resident Natural Killer cells.

From yeast to man--from mitochondria to liver regeneration: a new essential gene family

The purpose of this review is to bring to the attention of the reader the latest developments in research on an important new emerging gene family. The respective genes are found in eukaryotes from yeast to man and even on the genome of some doubled-stranded DNA viruses. They have essential functions in the biogenesis of mitochondria, the cell division cycle and, in higher eukaryotes, in the development of organs like liver and testis. The most important medical implication is their probable role in liver regeneration that will, therefore, be addressed in detail. Aspects of molecular biology, medical implications and problems of developmental biology reflect the complexity of the functions of these proteins and the subjects of the respective research. This is just the beginning of an interdisciplinary effort directed towards the elucidation of the precise function of these essential factors inside the eukaryotic cell. In the general part of this review, we will concentrate on the history of the discovery of these genes and on a summary of their characteristic features. In the more specialized section, the specific role as augmenter of liver regeneration will be addressed in detail.

Highly divergent amino termini of the homologous human ALR and yeast scERV1 gene products define species specific differences in cellular localization

The yeast scERV1 gene product is involved in the biogenesis of mitochondria and is indispensable for viability and regulation of the cell cycle. Recently the general importance of this gene for the eukaryotic cell was shown by the identification of a structural and functional human homologue. The homologous mammalian ALR (Augmenter of Liver Regeneration) genes from man, mouse and rat are involved in the phenomenon of liver regeneration. A low expression rate of the genes is found in all investigated cells and mammalian tissues but it is specifically induced after damage of liver organs and is especially high during spermatogenesis. The alignment of the different proteins identifies a highly conserved carboxy terminus with more than 40% identical amino acids between yeast and mammals. The conserved carboxy terminus is functionally interchangeable between distantly related species like yeast and man. In contrast, the amino terminal parts of the proteins display a high degree of variability and significant differences even among closely related species. This finding leads to the problem whether the amino termini have comparable or divergent functions in different species. In this study we demonstrate by heterologous complementation experiments in yeast that the complete human ALR protein with its own amino terminus is not able to substitute for the yeast scERV1 protein. Fusion proteins of Alrp and scErv1p with the green fluorescence protein were created to investigate the respective subcellular localizations of these homologous proteins in yeast and human cells. In yeast cells human Alrp accumulates in the cytoplasm in contrast to yeast scErv1p that is preferentially associated with yeast mitochondria. Comparable studies with human cells clearly show that the homologous human Alrp is located in the cytosol of these cells. Fractionation experiments and antibody tests with yeast and human mitochondria and cellular extracts verify these findings.

The in vivo effect of hepatotrophic factors augmenter of liver regeneration, hepatocyte growth factor, and insulin-like growth factor-II on liver natural killer cell functions

Fine balanced sequential changes of the levels of circulating hepatotrophic factors are essential for normal liver regeneration. Our recent studies have indicated that liver-resident natural killer (NK) cells are important regulators of liver regeneration and have raised the possibility that hepatotrophic factors might mediate their activities through NK cells. In the present study, we assessed the effects of in vivo administration of three hepatotrophic factors (augmenter of liver regeneration [ALR], insulin-like growth factor-II [IGF-II], and hepatocyte growth factor [HGF]) on NK cells in normal rats. Each of the three, given over a 1-day period in doses known to produce hepatotrophic activity, induced inhibition of NK cell cytotoxic activities in the population of mononuclear leukocytes (MNL) in the liver, but not in MNL from the spleen or peripheral blood. In contrast to these results obtained by the whole animal treatment, the three molecules had no effect on NK cell functions when added to cultures of MNL from the livers, spleens, or blood of untreated rats. These data support and extend our previously advanced hypothesis that ALR and other hepatotrophic factors play an important role in liver regeneration by regional regulation of NK cells through some as-yet-unknown intermediary mechanism.

The in vivo effect of hepatotrophic factors augmenter of liver regeneration, hepatocyte growth factor, and insulin-like growth factor-II on liver natural killer cell functions

Fine balanced sequential changes of the levels of circulating hepatotrophic factors are essential for normal liver regeneration. Our recent studies have indicated that liver-resident natural killer (NK) cells are important regulators of liver regeneration and have raised the possibility that hepatotrophic factors might mediate their activities through NK cells. In the present study, we assessed the effects of in vivo administration of three hepatotrophic factors (augmenter of liver regeneration [ALR], insulin-like growth factor-II [IGF-II], and hepatocyte growth factor [HGF]) on NK cells in normal rats. Each of the three, given over a 1-day period in doses known to produce hepatotrophic activity, induced inhibition of NK cell cytotoxic activities in the population of mononuclear leukocytes (MNL) in the liver, but not in MNL from the spleen or peripheral blood. In contrast to these results obtained by the whole animal treatment, the three molecules had no effect on NK cell functions when added to cultures of MNL from the livers, spleens, or blood of untreated rats. These data support and extend our previously advanced hypothesis that ALR and other hepatotrophic factors play an important role in liver regeneration by regional regulation of NK cells through some as-yet-unknown intermediary mechanism.

Proliferative activity of gastric epithelium in progressive stages of Helicobacter pylori infection

Helicobacter pylori (HP) infection is the main etiopathogenetic agent responsible for inflammatory and ulcerative changes in gastroduodenal mucosa and the basis for both intestinal and diffuse types of gastric carcinoma. In this latter case, intestinal metaplasia is the intermediary between gastritis and cancer. In this study we describe the proliferative activity of gastric epithelium in the progressive stages of HP infection. The expression of proliferating cell nuclear antigen (PCNA), which has proven to be a reliable method for this evaluation, was used as a marker. The study was performed on endoscopic biopsies of the gastric antrum of 40 patients, who were divided into five groups, eight in each group: normal histology and endoscopy, HP-; histological HP+ gastritis with normal endoscopy; histological HP+ gastritis with endoscopic evidence of chronic erosions; complete and incomplete intestinal metaplasia in a HP+ stomach. PCNA was detected by immunohistochemistry and expressed as labeling index, ie, percentage of positive nuclei either in the whole or upper third of foveolae. Our data show a progressive increase of epithelial proliferation in the successive stages of HP infection ranging from gastritis alone to the development of incomplete intestinal metaplasia, a well-known precancerous condition. The proliferative pattern tended to expand towards the upper foveolar third, which in normal conditions does not represent a site of epithelial renewal. These alterations may be related to the development of neoplastic transformations of gastric epithelium. It is well known that genetic mutations are facilitated in proliferating cells. Therefore, our results indicate that the high epithelial turnover, expressed by PCNA LI, may be an indicator of increased risk of neoplastic changes in long-standing untreated HP+ chronic gastritis.

Modulation of rat hepatocyte proliferation by bile salts: in vitro and in vivo studies

In this study, the stimulatory effect of bile salts (BS) was evaluated both in vitro, using hepatocyte primary cultures, and in vivo, in normal and 40% partially hepatectomized rats previously fed on BS-enriched diets for 4 weeks. In vitro results show that conjugated cholate (CA) and chenodeoxycholate (CDCA) augmented proliferative activity in rat hepatocytes cultured in absence of mitogens, whereas conjugated deoxycholate (DCA), and ursodeoxycholate (UDCA) did not have any significant effect. None of these BSs increased significantly the replicative response induced by submaximal concentrations of epidermal growth factor (EGF). In vivo, at the end of dietary treatment all animals fed on CA or DCA but not those fed on either CDCA, or UDCA, or tauroursodeoxycholate (TUDCA) developed cholestatic hepatitis and a burst of damage-induced hepatocyte proliferation. After 40% partial hepatectomy (PH), CA- and DCA-treated groups underwent a deterioration of cholestatic hepatitis. On the other hand, in CDCA-, and UDCA-, and TUDCA-treated groups liver histology, serum glutamic pyruvic transaminase (SGPT) and cholestasis indices did not change significantly compared with controls. As far as the proliferative activity, a significant increase was observed not only in CA and DCA but also in UDCA- and TUDCA-fed groups compared with controls, whereas a slight decrease was observed in CDCA-treated animals. In conclusion, our data indicate that conjugated BSs had only a modest stimulatory effect on hepatocyte proliferation in vitro. However, in vivo, in PH rats, UDCA or TUDCA treatment determined a further increase of hepatocellular proliferation not attributable to hepatotoxic effects. Our result suggest that modifications of bile acid pool could modulate hepatocellular proliferation.

Changes of liver-resident NK cells during liver regeneration in rats

To determine the role of NK cells in regulation of tissue growth, the phenotype and function of liver-resident NK cells were studied after 70% partial hepatectomy in rats. The process of liver regeneration was generally completed by day 14. In contrast, the number of liver-resident NK cells (NKR-P1bright) was restored as early as day 3 after partial hepatectomy. However, spontaneous functions of liver-resident NK cells, including killing of YAC-1 and P815 targets, Ab-dependent cellular cytotoxicity, and redirected killing via NKR-P1, were continuously suppressed throughout the entire period of liver regeneration (from 3 h to 14 days). Augmentation of NK cytotoxicity against P815 targets and induction of NK cell adherence to plastic following 24 h of IL-2 stimulation showed a similar pattern of suppression. However, IL-2-induced augmentation of YAC-1 killing, proliferation and generation of adherent NK cells, and LAK activity in 5- to 7-day cultures were found to be suppressed only during the first 24 h and increased between days 2 and 7 after hepatectomy. Sorted NK cells (> or = NKR-P1bright) from liver-resident mononuclear leukocytes 24 h after partial hepatectomy showed the same pattern of suppression as unsorted mononuclear leukocytes. In contrast to liver-resident NK cells, no significant changes were detected in peripheral blood or spleen NK cells of rats following partial hepatectomy. Of particular interest, in normal liver, hepatocytes were resistant to NK lysis, while resident NK cells were cytotoxic for various NK-sensitive targets. In contrast, during the early period of liver regeneration, when hepatocytes were sensitive to lysis by liver-resident NK cells of normal rats, NK cells obtained from regenerating liver tissues were unable to mediate cytotoxicity. At the final phase of liver regeneration (days 7-14 after hepatectomy), both resistance of hepatocytes to killing by NK cells and cytotoxicity of liver-resident lymphocytes against hepatocytes from regenerating liver were simultaneously restored. In vivo depletion of NK cells by injection of rats with anti-NKR-P1 mAb resulted in a significant augmentation of liver regeneration subsequent to partial hepatectomy. Our data suggest that liver-resident NK cells may be involved in regulation of the extent of liver regeneration.

Changes of liver-resident NK cells during liver regeneration in rats

To determine the role of NK cells in regulation of tissue growth, the phenotype and function of liver-resident NK cells were studied after 70% partial hepatectomy in rats. The process of liver regeneration was generally completed by day 14. In contrast, the number of liver-resident NK cells (NKR-P1bright) was restored as early as day 3 after partial hepatectomy. However, spontaneous functions of liver-resident NK cells, including killing of YAC-1 and P815 targets, Ab-dependent cellular cytotoxicity, and redirected killing via NKR-P1, were continuously suppressed throughout the entire period of liver regeneration (from 3 h to 14 days). Augmentation of NK cytotoxicity against P815 targets and induction of NK cell adherence to plastic following 24 h of IL-2 stimulation showed a similar pattern of suppression. However, IL-2-induced augmentation of YAC-1 killing, proliferation and generation of adherent NK cells, and LAK activity in 5- to 7-day cultures were found to be suppressed only during the first 24 h and increased between days 2 and 7 after hepatectomy. Sorted NK cells (&gt; or = NKR-P1bright) from liver-resident mononuclear leukocytes 24 h after partial hepatectomy showed the same pattern of suppression as unsorted mononuclear leukocytes. In contrast to liver-resident NK cells, no significant changes were detected in peripheral blood or spleen NK cells of rats following partial hepatectomy. Of particular interest, in normal liver, hepatocytes were resistant to NK lysis, while resident NK cells were cytotoxic for various NK-sensitive targets. In contrast, during the early period of liver regeneration, when hepatocytes were sensitive to lysis by liver-resident NK cells of normal rats, NK cells obtained from regenerating liver tissues were unable to mediate cytotoxicity. At the final phase of liver regeneration (days 7-14 after hepatectomy), both resistance of hepatocytes to killing by NK cells and cytotoxicity of liver-resident lymphocytes against hepatocytes from regenerating liver were simultaneously restored. In vivo depletion of NK cells by injection of rats with anti-NKR-P1 mAb resulted in a significant augmentation of liver regeneration subsequent to partial hepatectomy. Our data suggest that liver-resident NK cells may be involved in regulation of the extent of liver regeneration.

Does tauroursodeoxycholic acid (TUDCA) treatment increase hepatocyte proliferation in patients with chronic liver disease?

Despite numerous studies on the effects of bile salts therapy in chronic liver disease, there are no reports on the influence such therapy has on hepatocyte proliferation. The aim of this preliminary study was to evaluate the effect of TUDCA on hepatocyte proliferation in 5 patients with HCV-correlated chronic liver disease. All patients were treated with TUDCA (10-13 mg/day) for three months and the determination of PCNA (Proliferating Cell Nuclear Antigen) expression was used to assess the proliferative activity of hepatocytes at the beginning and at the end of treatment. TUDCA reduced both ALT and Knodell's score in the 5 patients in whom a significant increase of PCNA-LI (p < 0.05) was observed after treatment. TUDCA administration seems to stimulate hepatocyte proliferation in man.

Cell proliferation and oncogene expression after bile duct ligation in the rat: evidence of a specific growth effect on bile duct cells

The proliferative response of the rat liver was measured after temporary or permanent total biliary obstruction (BDO) and in different regions after selective ligation of the lobar ducts draining the right 60% of the hepatic mass. The results were compared with those after 70% partial hepatectomy (PH). Cell proliferation was assessed globally by measuring DNA synthesis and stratified to the separate cell populations with cytostaining techniques that allowed distinction of hepatocytes, duct cells, and nonparenchymal cells (NPCs). In selected experimental groups, gene expression was determined of transforming growth factor-beta 1 (TGF beta-1), prothrombin, c-erb-B2, transforming growth factor alpha (TGF alpha), human Cyclophilin (CyP), and 28S ribosomal RNA. The stimulation of a proliferative response to total BDO required obstruction for longer than 24 hours, but after this deligation did not switch off regeneration. In the first week after permanent BDO, there was progressive infiltration of NPCs, fibrous linkage of some portal areas, and a crescendo of DNA synthesis that was obvious at 24 hours, maximal at 48 hours, and back nearly to baseline at 6 days. At the 2-day mark, the bile duct cells had a 17-fold increase in proliferation, accompanied by a threefold to fourfold increase in hepatocyte renewal. Little or no increase in expression of TGF alpha or the hepatocyte-specific prothrombin gene was detectable in the first 48 hours, whereas levels of the oncogene c-erb-B2 that is associated with cholangiocarcinoma were expressed from 48 to 96 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatocyte proliferation and gene expression induced by triiodothyronine in vivo and in vitro

Subcutaneous injections of hormone triiodothyronine in rats resulted in peak blood levels at 24 hr with return to baseline by 96 hr. The injections stimulated a liver regeneration response that resembled in timing and in magnitude of DNA synthesis (peak, 24 hr) that induced by 40% hepatic resection. The principal proliferation was of hepatocytes. Although there were some temporal differences from the gene expression of transforming growth factor-alpha, transforming growth factor-beta, and c-Ha-ras that are known to follow partial hepatectomy, the overall profile of these changes was similar to those after partial resection. The effect was liver specific and could be reproduced three times with no diminution in response in the same animal with injections at 10-day intervals. No response was detected in kidney or intestine. This effect in intact animals contrasted with the minimal ability of triiodothyronine to stimulate hepatocytes in culture. However, when the culture medium was enriched with epidermal growth factor, there was a dose-related response to triiodothyronine. The totality of these experiments provides a preliminary basis for the creation with pharmacological techniques of an in vivo hyperplastic hepatic condition permissive of transfection of new genes, as an alternative to partial hepatectomy. Although triiodothyronine was the test agent used, other hepatic growth factors singly or in combination could be candidates for this purpose.

Cloning and sequence analysis of the rat augmenter of liver regeneration (ALR) gene: expression of biologically active recombinant ALR and demonstration of tissue distribution

A full-length cDNA clone encoding a purified augmenter of liver regeneration (ALR) factor prepared from the cytosol of weanling rat livers was isolated. The 1.2-kb cDNA included a 299-bp 5' untranslated region, a 375-bp coding region, and a 550-bp 3' untranslated region. It encoded a protein consisting of 125 amino acids. The molecular weight of ALR calculated from the cDNA was 15,081, which is consistent with the size estimated by SDS/PAGE under reducing conditions. The molecular weight of the purified native ALR estimated by SDS/PAGE under nonreducing conditions was approximately 30,000; thus ALR apparently has a homodimeric structure. The recombinant ALR produced by expression of the cDNA in COS cells was tested in vivo in the canine Eck fistula model and found to have potency equivalent to the purified native ALR. The 125-aa sequence deduced from the rat ALR cDNA shows 50% homology to the amino acid sequence of the gene for oxidative phosphorylation and vegetative growth in the yeast Saccharomyces cerevisiae.

Estrogens, androgens, and EGF receptor expression in gastric carcinoma induced by N-methyl-N'-nitro-N-nitrosoguanidine

Complex and conflicting relationships between epidermal growth factor (EGF), estrogens (E), androgens (A), and related receptors (EGF-R, E-R, A-R) have been reported in different biological situations associated with cell proliferation. There is also evidence that EGF and sex hormone receptors may be involved in normal and neoplastic growth of the gastrointestinal mucosa. In this study, we investigated the behavior of EGF receptors and sex hormone and related receptors, during N-methyl-N'-nitro-N-nitrosoguanidine (NG)-induced gastric carcinogenesis in Sprague-Dawley male rats. Four groups of 15 rats each (10 NG-treated and five controls) were sacrificed after 1, 20, 30, and 40 weeks of treatment. Gastric tissue from each rat was processed for receptor status (number and affinity) and proliferative activity. A significant and progressive decrease of A-R and EGF-R was observed starting from the 20th week, while no change of E-R occurred throughout the experiment. Cell proliferation in the gastric mucosa of NG-treated rats increased after 30 weeks of treatment. These data indicate that NG treatment is able to modify the receptor status of gastric mucosa in rats.

Small-for-size liver transplanted into larger recipient: a model of hepatic regeneration

Orthotopic liver transplantation was performed in 60 recipient rats weighing 200 to 250 gm. Sixty rats of the same strain were used as liver donors, 30 weighing 100 to 140 gm (small for size) and the other 30 weighing 200 to 250 gm (same size). After 1, 2, 3, 4, 7 and 14 days (n = 5 each) DNA synthesis, nuclear thymidine labeling and mitoses were increased in both the small-for-size and same-size groups, but significantly more in the former. These changes were maximal after 48 to 72 hr, similar to but later than the well-known regeneration response after partial hepatectomy, which peaks at 24 hr in rats. Indirect indexes of regeneration of the transplanted livers also were measured: plasma or serum ornithine decarboxylase; insulin and glucagon serum levels; estradiol and testosterone serum levels (and their nuclear and cytosolic receptors); and transforming growth factor-beta, c-Ha-ras and c-jun mRNA expressions. With the small-for-size transplantation, these followed the same delayed pattern as the direct regeneration parameters. The small livers gradually increased in size over the course of 1 to 2 wk and achieved a volume equal to that of the liver originally present in the recipient. In contrast, no significant liver weight gain occurred in the transplanted livers from same-size donors despite the evidence of regeneration by direct indexes, but not by most of the surrogate parameters, including ornithine decarboxylase.

Interphasic nucleolar organizer regions expression and cell kinetics evaluation during gastric carcinogenesis induced by nitrosoguanidine in the rat

An increased number of interphasic nucleolar organizer regions containing ribosomal cistrons associated with argyrophilic proteins (AgNORs) has been described in human malignant tumor cells. In this study variations in AgNOR numbers have been compared with changes of cell kinetics, evaluated by the mitotic count (MC) and bromodeoxyuridine labeling index (BrdU LI), during gastric carcinogenesis induced with N-methyl-N'-nitro-N-nitrosoguanidine (NG) in rats. Significant differences (2 P < 0.005) in AgNOR mean numbers, evaluated in the antral isthmic cells, in MC mean values and BrdU LI, evaluated in the whole antral cellular population, were found when comparing areas of acute gastritis, atrophy and hyperplasia in NG-treated rats with the normal mucosa in controls. No differences were observed in MC and BrdU LI between normal antrum and carcinoma cells which showed an AgNORs mean number lower than in the isthmic cells of controls (2 P < 0.005). Moreover, significant correlations were found comparing changes in AgNOR numbers with MC (r = 0.89, P < 0.001) and BrdU LI (r = 0.66, P < 0.001) in different lesions. These data show that evaluation of AgNOR numbers does not allow the identification of malignant cells in NG-induced gastric carcinoma. However AgNOR quantification seems to be a reliable index of cell kinetics and related well with the cellular dividing fraction.

Relationship between plasma and hepatic cytosolic levels of ornithine decarboxylase (ODC) and thymidine kinase (TK) in 70% hepatectomized rats

Ornithine decarboxylase (ODC) and thymidine kinase (TK) are enzymes important for DNA synthesis, a process that is critical for cell renewal and regeneration. As such, they already have been used as surrogate markers of regeneration in tissue. In the present study, the activity of these two enzymes in plasma of rats and regenerating hepatic tissue following a 70% hepatectomy were determined. The results demonstrate that the changes in these enzyme activities in plasma reflect the changes obtained in the liver tissue. Thus, blood levels of ODC and TK can be used as a less invasive and nondestructive means of monitoring the regenerative response of the liver and possibly other tissues.

Hormonal and enzymatic parameters of hepatic regeneration in patients undergoing major liver resections

Thirteen patients who underwent 40% to 80% removal of their livers had blood samples drawn initially and daily on postoperative days 1 to 7. The enzyme marker of heightened polyamine metabolism, ornithine decarboxylase, and the indicator of DNA synthesis, thymidine kinase, were measured. In addition, the hormones (insulin, glucagon, estradiol and androgen), which in animals are known to reflect and possibly modulate regeneration, were measured. Changes in all these indices followed the same pattern as in rats, dogs and swine but at a slower rate. Ornithine decarboxylase and estradiol increased within 24 hr, but thymidine kinase and insulin rises did not become statistically significant until 3 to 5 days. Using these plasma or serum indices as surrogate measures of biochemical events in the liver itself, regeneration reached a maximum after 4 or 5 days. By computed tomography scan analysis, restoration of hepatic cell mass was not complete until 3 wk.

Effect of ranitidine on acetaminophen-induced hepatotoxicity in dogs

The effect of ranitidine administration upon the hepatotoxic effect produced by a multidose acetaminophen administration regimen was examined. Seventy-two dogs received three subcutaneous injections of acetaminophen (750, 200, 200 mg/kg body wt) in DMSO (600 mg/ml) at time zero, 9 hr later, and 24 hr after the first dose. Ten control animals (group I) were not given ranitidine, the remaining 62 dogs received an intramuscular injection of ranitidine 30 min before each acetaminophen dose. Three different doses of ranitidine were used (mg/kg body wt): 50 mg, group II (33 dogs); 75 mg, group III (14 dogs); 120 mg, group IV (15 dogs). Ranitidine reduced the expected acetaminophen-induced hepatoxicity in a dose-response manner. Moreover, a significant correlation was found between the ranitidine dose and the survival rate, as evidenced by transaminase levels in the serum and histology of the liver. This model of fulminant hepatic failure induced by acetaminophen and its modulation with ranitidine provides clinical investigators with a research tool that will be useful in the future investigation of putative medical and surgical therapies being investigated for use in the clinical management of fulminant hepatic failure. Because of the size of the animal used in this model, frequent and serial analyses of blood and liver were available for study to determine the effect of therapy within a given animal as opposed to within groups of animals.

The effect of estrogen and tamoxifen on hepatocyte proliferation in vivo and in vitro

We have previously shown that changes in estrogen-hepatocyte interaction occur during liver regeneration. Following 70% hepatectomy, estrogen levels in the blood were elevated, the number of estrogen receptors in the liver was increased and there was an active translocation of estrogen receptors from the cytosol to the nucleus. The injection of tamoxifen, an estrogen antagonist, inhibits hepatocyte proliferation following partial hepatectomy. The administration of 1 microgram tamoxifen per gm body weight at zero time or 6 hr after the operation resulted in a significant inhibition both of DNA synthesis and of the number of cells in mitosis. Injections of tamoxifen 12 hr or later after the operation had no effect. Concomitant injections of equimolar amounts of estrogen abolished the inhibition by tamoxifen. The effects of estrogen and tamoxifen were also tested on hepatocytes in primary culture. Estrogens in the presence of 5% normal rat serum stimulated hepatocyte DNA synthesis as determined by [3H]thymidine incorporation and the labeling index, whereas epidermal growth factor-induced DNA synthesis in the absence of normal rat serum was strongly inhibited. Tamoxifen, in contrast, inhibited DNA synthesis of hepatocytes in the presence of 5% normal rat serum and reversed the stimulatory effect of estrogen in the same system. Attempts to elucidate the mechanism of tamoxifen inhibition in vitro indicated that one effect of tamoxifen is to prevent the amiloride-sensitive Na+ influx necessary to initiate hepatocyte proliferation.

A dog model for acetaminophen-induced fulminant hepatic failure

The development of a large animal model of fulminant hepatic failure produced with acetaminophen that should be useful in the development and evaluation of potential medical therapies for the important clinical problem of fulminant hepatic failure is described. Acetaminophen in dimethyl sulfoxide (600 mg/ml) given as three subcutaneous injections, with the first dose (750 mg/kg body wt) being given at noon, the second dose (200 mg/kg body wt) being given 9 h later, and the third dose (200 mg/kg body wt) being given 24 h after the initial dose consistently produces fulminant hepatic failure in dogs. The dimethyl sulfoxide vehicle, injected intramuscularly, does not influence either animal survival or hepatic function in control-treated dogs. No deaths occur within the first 36 h. By 72 h after initial drug administration, the mortality is 90%. Histopathological and biochemical investigations demonstrate a high degree of hepatocellular necrosis in nonsurviving animals without appreciable damage to the kidneys, lungs, or heart. The drug schedule and preparation outlined avoids the administration of large volumes of vehicle and results in prolonged high levels of acetaminophen in the blood sufficient to induce severe hepatic injury. Ranitidine (120 mg/kg body wt i.m.) given 30 min before each acetaminophen dose significantly reduces the mortality and hepatic necrosis produced using this model. This model satisfies all criteria established by Miller et al. for the production of a suitable large animal model of fulminant acute hepatic failure.

Effect of cimetidine, ranitidine, famotidine and omeprazole on hepatocyte proliferation in vitro

Recently reports have indicated that both cimetidine and ranitidine delay cell proliferation in rats following 70% partial hepatectomy and result in an increased mortality following this procedure. The present study was designed to determine whether three H2 blocking agents (cimetidine, ranitidine, famotidine) and a new, powerful antisecretory drug (omeprazole) specifically influence hepatocyte proliferation in primary culture. Hepatocytes were isolated from livers of normal male rats by the standard collagenase perfusion technique. Hepatic DNA synthesis and percent of labelled nuclei were determined after 48 h incubation. Hepatocytes in culture were incubated with the H2 blocking agents and omeprazole or with different concentrations of serum obtained from sham-operated or 70% hepatectomized rats treated or not with the same agents. Rats were injected intraperitoneally at 8:00 a.m. on two consecutive days. In hepatectomized rats, the first dose was injected at 8:00 a.m. immediately after surgery, the second, 24 h later. The serum of sham-operated or 70% hepatectomized rats that did not receive drugs served as control. No changes in DNA synthesis, percentage of labelled nuclei and transaminase were detected when the agents were added to the hepatocytes in culture at concentrations within the effective pharmacological dosage and 30 times higher. Similarly, no changes in these parameters were obtained when different concentrations of serum obtained from sham-operated rats treated with H2 blocking agents or omeprazole were added to the basal culture medium. However, a significant inhibition of DNA synthesis and of percentage of labelled nuclei was observed when hepatocytes were incubated in the presence of serum from 70% hepatectomized rats that had been treated with cimetidine or with ranitidine. The serum of 70% hepatectomized rats treated with famotidine and omeprazole had no effect on hepatocyte proliferation in vitro. No effect on transaminase was found in these conditions.

Nuclear and cytosolic estrogen receptors in human colon carcinoma and in surrounding noncancerous colonic tissue

The measurement of estrogen as well as progesterone receptors has been applied clinically to predict the effectiveness of endocrine therapy in patients with breast or endometrial carcinoma. The presence of cytosolic estrogen receptors in human colorectal carcinomas has been reported by several different groups during the past 10 yr. The aim of our current study was to evaluate the estrogen binding activity in the nuclear and cytosolic fractions of these carcinomas, as well as in surrounding noncancerous colonic tissue. Twenty-six patients, operated on for colorectal carcinoma, were studied: 16 were men and 10 were postmenopausal women, mean age 61 yr (range 43-78 yr). In neoplastic tissue, cytosolic estradiol receptors were detected in 42.3% of the patients (women 40%, men 43.7%). The values for cytosolic estrogen receptor ranged from 118 to 1214 fmol/g wet colon. Nuclear estrogen receptors were detectable in 46.1% of the patients (women 40%, men 50%) and their values displayed a range from 3.4 to 2554 fmol/g wet colon. In 30.7% of the patients, both nuclear and cytosolic receptors were demonstrated. In 38.4% of the patients, receptors were found in neither cytosol nor nuclei. Receptor positivity in men was most frequently associated with tumors removed from the rectum, and those with Dukes' classification of C1. In the surrounding noncancerous tissue cytosolic estrogen receptors were also detected (range 133-1105 fmol/g wet colon) and were present in 34.6% of the patients (women 30%, men 37.5%). Nuclear estrogen receptors (range 225-1105 fmol/g wet colon) were detected in 57.6% of the patients (women 40%, men 68.7%). In 23% of the patients, both nuclear and cytosolic receptors were demonstrated. In 30.7% of the patients, no receptors were found in either cytosol or nucleus. Therefore, the presence of cytosolic or nuclear estrogen receptors, or both, in 61.6% of human colorectal cancer specimens emphasizes the need to evaluate both forms of these receptors for studies of potential hormone dependence in these tumors.