Gut microbiota promote liver regeneration through hepatic membrane phospholipid biosynthesis

BACKGROUND & AIMS

Hepatocyte growth and proliferation depends on membrane phospholipid biosynthesis. Short-chain fatty acids (SCFAs) generated by bacterial fermentation, delivered through the gut-liver axis, significantly contribute to lipid biosynthesis. We therefore hypothesized that dysbiotic insults like antibiotic treatment not only affect gut microbiota, but also impair hepatic lipid synthesis and liver regeneration.

METHODS

Stable isotope labeling and 70% partial hepatectomy (PHx) was carried out in C57Bl/6J wild-type mice, in mice treated with broad-spectrum antibiotics, in germ-free mice and mice colonized with minimal microbiota. The microbiome was analyzed by 16S rRNA gene sequencing and microbial culture. Gut content, liver, blood and primary hepatocyte organoids were tested by mass spectrometry-based lipidomics, quantitative reverse-transcription PCR (qRT-PCR), immunoblot and immunohistochemistry for expression of proliferative and lipogenic markers. Matched biopsies from hyperplastic and hypoplastic liver tissue of patients subjected to surgical intervention to induce hyperplasia were analyzed by qRT-PCR for lipogenic enzymes.

RESULTS

Three days of antibiotic treatment induced persistent dysbiosis with significantly decreased beta-diversity and richness, but a massive increase of Proteobacteria, accompanied by decreased colonic SCFAs. After PHx, antibiotic-treated mice showed delayed liver regeneration, increased mortality, impaired hepatocyte proliferation and decreased hepatic phospholipid synthesis. Expression of the lipogenic enzyme SCD1 was upregulated after PHx but delayed by antibiotic treatment. Germ-free mice essentially recapitulated the phenotype of antibiotic treatment. Phospholipid biosynthesis, hepatocyte proliferation, liver regeneration and survival were rescued in gnotobiotic mice colonized with a minimal SCFA-producing microbial community. SCFAs induced the growth of murine hepatocyte organoids and hepatic SCD1 expression in mice. Further, SCD1 was required for proliferation of human hepatoma cells and was associated with liver regeneration in human patients.

CONCLUSION

Gut microbiota are pivotal for hepatic membrane phospholipid biosynthesis and liver regeneration.

IMPACT AND IMPLICATIONS

Gut microbiota affect hepatic lipid metabolism through the gut-liver axis, but the underlying mechanisms are poorly understood. Perturbations of the gut microbiome, e.g. by antibiotics, impair the production of bacterial metabolites, which normally serve as building blocks for membrane lipids in liver cells. As a consequence, liver regeneration and survival after liver surgery is severely impaired. Even though this study is preclinical, its results might allow physicians in the future to improve patient outcomes after liver surgery, by modulation of gut microbiota or their metabolites.

OUP accepted manuscript

Although a high prevalence of COVID-19-associated pulmonary aspergillosis has been reported, it is still difficult to distinguish between colonization with Aspergillus fumigatus and infection. Concomitantly, similarities between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and hypersensitivity pneumonitis were suggested. The objective of this study was to investigate retrospectively if precipitin assays targeting A. fumigatus could have been useful in the management of SARS-CoV-2 patients hospitalized in an Intensive Care Unit (ICU) in 2020. SARS-CoV-2 ICU patients were screened for Aspergillus co-infection using biomarkers (galactomannan antigen, qPCR) and culture of respiratory samples (tracheal aspirates and bronchoalveolar lavage). For all these patients, clinical data, ICU characteristics and microbial results were collected. Electrosyneresis assays were performed using commercial A. fumigatus somatic and metabolic antigens. ELISA were performed using in-house A. fumigatus purified antigen and recombinant antigens.

Our study population consisted of 65 predominantly male patients, with a median ICU stay of 22 days, and a global survival rate of 62%. Thirty-five patients had at least one positive marker for Aspergillus species detection. The number of arcs obtained by electrosyneresis using the somatic A. fumigatus antigen was significantly higher for these 35 SARS-CoV-2 ICU patients (P 0.01, Welch's t-test). Our study showed that SARS-CoV-2 ICU patients with a positive marker for Aspergillus species detection more often presented precipitins towards A. fumigatus. Serology assays could be an additional tool to assess the clinical relevance of the Aspergillus species in respiratory samples of SARS-CoV-2 ICU patients.

Interlaboratory evaluation of Mucorales PCR assays for testing serum specimens: A study by the fungal PCR Initiative and the Modimucor study group

Interlaboratory evaluations of Mucorales qPCR assays were developed to assess the reproducibility and performance of methods currently used. The participants comprised 12 laboratories from French university hospitals (nine of them participating in the Modimucor study) and 11 laboratories participating in the Fungal PCR Initiative. For panel 1, three sera were each spiked with DNA from three different species (Rhizomucor pusillus, Lichtheimia corymbifera, Rhizopus oryzae). For panel 2, six sera with three concentrations of R. pusillus and L. corymbifera (1, 10, and 100 genomes/ml) were prepared. Each panel included a blind negative-control serum. A form was distributed with each panel to collect results and required technical information, including DNA extraction method, sample volume used, DNA elution volume, qPCR method, qPCR template input volume, qPCR total reaction volume, qPCR platform, and qPCR reagents used. For panel 1, assessing 18 different protocols, qualitative results (positive or negative) were correct in 97% of cases (70/72). A very low interlaboratory variability in Cq values (SD = 1.89 cycles) were observed. For panel 2 assessing 26 different protocols, the detection rates were high (77-100%) for 5/6 of spiked serum. There was a significant association between the qPCR platform and performance. However, certain technical steps and optimal combinations of factors may also impact performance. The good reproducibility and performance demonstrated in this study support the use of Mucorales qPCR as part of the diagnostic strategy for mucormycosis.

Hypersensitivity pneumonitis in a cystic fibrosis patient

Hypersensitivity pneumonitis (HP) is a chronic inflammatory lung disease caused by repeated inhalation of antigenic substances. We present a case of metalworking fluids (MWFs)-HP sensitized to Pseudomonas oleovorans in a cystic fibrosis patient. This case illustrates that HP diagnosis remains challenging, especially in patients with another pulmonary disease, and that serodiagnosis contributes to identifying the precise microorganism involved. It also demonstrates that P. oleovorans is an important secondary aetiological agent in MWF-HP, less known than Mycobacterium immunogenum.

The enzymes OSC1 and CYP716A263 produce a high variety of triterpenoids in the latex of Taraxacum koksaghyz

Only very little is known about the resin composition of natural rubber from the dandelion species Taraxacum koksaghyz, thus its full characterization could provide new insights into how the isoprenoid end-products influence the physical properties of natural rubber, and this resin might be a good source of highly diverse triterpenoids. Here, we present a comprehensive analysis of the triterpenoid composition in an acetone extract and identified 13 triterpenes and triterpenoids also including the so far unknown pentacyclic compounds lup-19(21)-en-3-ol (1) and its ketone lup-19(21)-en-3-one (2). We purified single triterpenes from the acetone extract by developing a two-step HPLC system that is adapted to the structural differences of the described triterpenoids. Furthermore, we isolated six different oxidosqualene cyclases (OSCs) and two P450 enzymes, and we functionally characterized TkOSC1 and CYP716A263 in Nicotiana benthamiana and Saccharomyces cerevisiae in detail. TkOSC1 is a multifunctional OSC that was capable of synthesizing at least four of the latex-predominant pentacyclic triterpenes (taraxasterol, α-, β-amyrin and lup-19(21)-en-3-ol) while CYP716A263 oxidized pentacyclic triterpenes at the C-3 position. The identified enzymes responsible for biosynthesis and modification of pentacyclic triterpenes in T. koksaghyz latex may represent excellent tools for bioengineering approaches to produce pentacyclic triterpenes heterologously.

Social representations concerning women daily experiences in prison

Introduction

Violence is a social and relational problem of humanity. When coming across a feminine jail population, the violence problem can take diverse proportions. Beyond being perpetrators of some sort of violence, these women can also be victims throughout their lives and even during their period of imprisonment.

Objective

Describe the social representations that imprisoned women have concerning daily experiences in prison.

Aims

Knowing the meaning of daily experience in prison to women.

Methods

Qualitative exploratory-descriptive field study, carried through with 15 prisoners of the feminine prison of Ribeirão Preto (SP-Brazil). A semi-structuralized interview was used. Results submitted to the content analysis technique.

Results

“Daily experiences with violence in prison”: they revealed feelings of abandonment and indifference to their health; they denounced suffering physical and psychological violence from employees and other female prisoners; the relation between them is marked by conflicts and aggressions. “Consequences of the arrest in the women's lives”: complained about the loss of contact with their familiars; there were relieves about lack of support and system's indifference for the readjustment in society.

Conclusions

This study contributed as stimulus and reference for the implementation of other researches with populations of prisons, amongst them the ones that aim to establish strategies for the reintegration of these women in society and the shift of paradigms related to them. Moreover, with the intention of supplementing researches with incarcerated women, we suggest studies that also have familiars and professionals (or visitors) as subjects.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Intimate partner violence and cognitive aspects of the perpetrator

Introduction

Violence against women, committed by an intimate partner, is a serious public health problem. On an international scope it has been researched the relation between intimate partner violence and cognitive aspects of aggressors.

Objective

To investigate if couples use violence to resolve conflicts and if there are differences in cognitive aspects of men in couples where there is intimate partner violence when compared to couples who have a harmonious relationship.

Method

The Revised Conflict Tactics Scale (CTS2) was used. The cognitive aspects of male partners was investigated by Wechsler Adult Intelligence Scale (WAIS-III), certain factors such as verbal and executive functions, to compare the testing results of men who have committed violence against their partners with those who did not.

Results

Thirty-one couples with intimate partner violence police reports and 31 couples who, according to their own perceptions, said to maintain harmonious marital relationship. The comparisons between groups allowed observing that even among couples who judge to be in a peaceful relationship, violent behaviors were detected. These behaviors tend to be naturalized and not considered as violence by partners. In regard to men's cognitive aspects, especially those related to WAIS-III verbal skills and impulse control, they possibly exert some influence to intimate partner violence.

Conclusion

The possible influence of cognitive aspects of the perpetrator on violence against women could be reduced through long-term actions, especially those concerned to early education, since this is the appropriate way to culturally change and to develop satisfactory social and cognitive skills of the individual.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

School Violence: Characterization of Occurrence's Records of a Public High School Institution

Introduction

Acts of indiscipline, incivility and violence are common in the school environment and reflect on physical and mental health of those involved.

Objective

To characterize conflict records made by students, teachers/others and parents/guardians in a Brazilian high school institution.

Method

Qualitative research, exploratory documental. Studied 113 records from 2014 to 2016.

Results

“Indiscipline and Incivility”–75 records (66 by teachers/others and 9 by students) of students: improper use of clothes and accessories, cell phone use in class, not bringing material, dating in school, conversations during class, do not respect the timetables, inappropriate jokes, disrupting activities, theft of materials and disrespect toward authority figures. “School violence”–22 records (12 by students, 9 by teachers/others and 1 by parent/guardian) of school violence: physical violence between students, psychological/verbal between students/teachers/others, and a match of sexual abuse. Three records (by teachers/others) of violence against the school: students destroyed teaching and cleaning materials and caused damage to the patrimony. Fifteen records (12 by students, 2 by parents/guardians and 1 by teacher) of school's violence: teachers’ harassment (excessive rigor in regard to school performance, clutter in the ratings, refusal to clarify doubts and inappropriate criticism on student's behavior) and institutional negligence (teachers’ delay, lack of clarification on teaching organization and supervision in practical activities).

Conclusion

Some students’ acts of indiscipline and incivility can be protests against the social control of the school. Assistance in case of conflicts and violence as well as preventive measures must be based on interdisciplinary and inter-sectorial articulation practice.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Violence as object of interdisciplinary research: Characterization of a Brazilian group of studies

Introduction

The interdisciplinary group of studies on violence (GREIVI), created in 2006, develops teaching, research and community extension activities related to violence and its impact on individuals’ mental health (victims or perpetrators).

Objective

To describe the subjects studied, the participants and the activities developed in the GREIVI in the period of 8 years.

Aims

Knowing the GREIVI's activities.

Method

Qualitative exploratory documentary study. Analysed 90 group monitoring reports from 2009 to 2016. The records were subjected to content analysis.

Results

Production: completed 11 research projects of undergraduate and postgraduate students; 7 in progress; presented 9 works in international scientific events; published 9 articles; 1 extension project in elementary school (2009 to 2016). Established partnership with international research and education institution to articulate and implement new projects. Topics discussed: definition, types and nature of violence; ecological model of violence; violence against women; and school violence. Activities: directed reading; discussions and exchange of experiences between the participants; presentation, discussion and advice on research and community extension projects; production and dissemination of scientific papers; technical visits and activities’ structuring and planning. Participants: professionals and undergraduate and graduate students from different areas (nursing, psychiatry, psychology, social work, education, biology and political advisor who works with the theme of violence).

Conclusion

The GREIVI have provided interdisciplinary space for discussion of different aspects of violence and the construction of research and extension projects to the community.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Microbiological characterization of 3193 French dwellings of Elfe cohort children

Although exposure to indoor microorganisms in early life has already been associated with respiratory illness or allergy protection, only a few studies have performed standardized samplings and specific microbial analysis. Moreover, most do not target the different groups of microorganisms involved in respiratory diseases (fungi, bacteria, dust mites). In our study, ten specific qPCR targets (6 fungal species, 1 family and 2 genera of bacteria, 1 house dust mite) were used to analyze the microorganism composition of electrostatic dust fall collector (EDC) from 3193 dwellings of the Elfe French cohort study. Multivariate analyses allowed us to show that the microbial composition of dwellings, assessed with simultaneous analysis of 10 microorganisms, can be characterized by four entities: three bacteria, house dust mite Dermatophagoïdes pteronyssinus, fungi Alternaria alternata, and five other molds. Some dwellings' intrinsic characteristics (occupational ratio, type of dwelling and presence of pets) clearly influence microorganism distribution, and six different profiles of dwellings, characterized by their composition in microorganisms, have been described across France. The use of these clusters seems promising in the evaluation of allergic risk. Allergic respiratory diseases will develop in the near future in some children of the Elfe cohort and will indicate to what extent our approach can be predictive of respiratory disease.

Evaluation of invasive aspergillosis risk of immunocompromised patients alternatively hospitalized in hematology intensive care unit and at home

Contrary to hospital exposure, little is known about the indoor fungal exposure of hematology patients at home. The aim of our study was to investigate the mold exposure of hematology patients both at home and at hospital to assess their invasive aspergillosis (IA) risk. Fungal exposure was assessed by quantifying opportunistic molds at hospital during hospitalization and in homes of 53 hematology patients. IA was diagnosed in 13 of 53 patients and invasive fungal infection (IFI) in one patient. In hospital, no opportunistic species, or low levels of opportunistic species, were found in 98% of weekly controls. Only 2% of hematology intensive care unit (ICU) controls showed a high level of Aspergillus fumigatus spores in corridor air. Five patients IA were hospitalized during these periods. Seven dwellings of 53 (5/14 dwellings of patients with IA/IFI and 2/39 dwellings of non-IA patients) had a percentage of A. fumigatus and Aspergillus flavus to total mold (significant predictor variable of IA/IFI in our study, general linear model, P-value = 0.02) as high as 15%. Maintaining a 'zero Aspergillus' goal at hospital is essential, and establishing specific and individually opportunistic mold monitoring at home could help to further reduce the IA risk through continuous surveillance.

PRACTICAL IMPLICATIONS

This study emphasizes the fact that preventive measures should not be aimed only at the hospital setting: among patients diagnosed with invasive aspergillosis/invasive fungal infection (IA/IFI), 5 of 14 (36%) were exposed to opportunistic fungal species at home exclusively. Moreover, four of these five patients were living in homes having the highest percentage of Aspergillus fumigatus and Aspergillus flavus (>15%), one of which had 48% of A. fumigatus. Therefore, our work supports the need for a counselor to carry out an environmental survey in patients’ homes.

Zur Zentralvene gerichtete Wanderung von Leberzellen der Ratte nach partieller Hepatektomie und nach Verabfolgung von Diäthylnitrosamin

Nach partieller Hepatektomie wurden Ratten 2 Pulse 3H-Thymidin gegeben und dadurch eine hohe Markierung der Leberzellen erreicht. Die Verschiebung der markierten Zellen zwischen Glissonscher Kapsel und Zentralvene wurde zwischen 5. — 91. Tag untersucht. Während das Maximum der Radioaktivität am Anfang portalwärts liegt, ist es am 91. Tag in der Nähe der Zentralvene gelegen. Da die Summe der Silberkörner im Autoradiogramm während dieser Zeit keine signifikante Abnahme zeigt, kann höchstens ein geringer Prozentsatz von markierten Zellen zugrunde gehen. Daraus ergibt sich aber, daß die Verschiebung der Markierung in der Richtung der Zentralvene nur durch Wanderung der Zellen gedeutet werden kann. Die gleiche Wanderung ergibt sich auch, wenn zusätzlich zur Hepatektomie noch Diäthylnitrosamin (DANA) gegeben wird. Nur gehen in diesem Fall etwa 90% der Zellen zugrunde. Bei weiteren Versuchen wurde ohne Hepatektomie DANA gegeben und gleichzeitig mit Thymidin markiert. Auch hier konnte die Verschiebung der Zellen und ebenso ein 90-proz. Verlust festgestellt werden.

25 years of HIV research on virology, virus restriction, immunopathogenesis, genes and vaccines

From 19 to 21 May 2008 an important meeting was held at the Pasteur Institute in Paris to mark the 25th Anniversary of the discovery of HIV as the aetiological agent of AIDS. This review summarizes the historical findings, recent work and future directions presented at this meeting.

Calibration of the lutetium-hafnium clock

Well-defined constants of radioactive decay are the cornerstone of geochronology and the use of radiogenic isotopes to constrain the time scales and mechanisms of planetary differentiation. Four new determinations of the lutetium-176 decay constant (lambda176Lu) made by calibration against the uranium-lead decay schemes yield a mean value of 1.865 +/- 0.015 x 10(-11) year(-1), in agreement with the two most recent decay-counting experiments. Lutetium-hafnium ages that are based on the previously used lambda176Lu of 1.93 x 10(-11) to 1.94 x 10(-11) year(-1) are thus approximately 4% too young, and the initial hafnium isotope compositions of some of Earth's oldest minerals and rocks become less radiogenic relative to bulk undifferentiated Earth when calculated using the new decay constant. The existence of strongly unradiogenic hafnium in Early Archean and Hadean zircons implies that enriched crustal reservoirs existed on Earth by 4.3 billion years ago and persisted for 200 million years or more. Hence, current models of early terrestrial differentiation need revision.

Immunocytochemical identification of DNA adducts, O6-methylguanine and 7-methylguanine, in respiratory and other tissues of rat, mouse and Syrian hamster exposed to 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone

The present paper reports about an immunocytochemical inventory of the cell types involved in the metabolic activation of the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) to a DNA methylating metabolite. The formation and distribution of the methylated DNA bases O6-methylguanine (O6-meGua) and 7-methylguanine (7-MeGua) were studied in respiratory tissues, oesophagus, liver, kidneys, pancreas, small intestine, colon and prostate of rat, mouse and hamster 6 h after treatment with a single dose of 30 mg NNK/kg. The tissue- and cell-specific distribution of O6-meGua- and 7-meGua-specific nuclear staining showed the same patterns and were remarkably similar in rat, mouse and hamster in spite of the diverging spectra of NNK-induced tumours in these species. In nasal tissue, a target for NNK-induced tumourigenesis in rat and hamster, but not in mouse, adduct-specific nuclear staining was observed in all three species in sustentacular cells, Bowman glands, respiratory epithelial cells and serous glands. Both methylated DNA bases were also observed in basal cells of the olfactory epithelium of rat and (occasionally) hamster, but not in those of the mouse. In the trachea, a target for NNK-induced tumourigenesis in hamster only, substantial adduct-specific nuclear staining was found in basal epithelial and glandular cells of the hamster; in the same cells of rat and mouse only a weak nuclear staining was found. In the lung, a common target for NNK-induced tumourigenesis, the formation of O6-meGua and 7-meGua was restricted predominantly to bronchial and proximal bronchiolar epithelium. Nuclear staining in the rat was occasionally found in alveolar cells and was also observed in hepatocytes. In the three species investigated, O6-meGua- and 7-MeGua-specific nuclear staining was found in target and non-target tissues. Apparently, and in analogy with results obtained in other studies, the species-specific organotropy for tumour formation of NNK is not exclusively determined by DNA methylation. Expanding methylation data with literature data on factors considered to be involved in tumour formation, namely proliferation, toxicity and DNA repair among others, still did not lead to a satisfactory explanation for the species-specific organotropy observed. Additional factors (yet to be identified), need to be taken into account in order to explain (and predict) tumourigenic effects induced by monofunctional methylating agents.

Distraction resulting from disease related words in alcohol-dependent inpatients: a controlled dichotic listening study

To test whether alcoholics develop an information processing bias towards disease-related stimuli, 30 alcoholic inpatients and 30 controls were administered a dichotic listening task. Three different stimulus types were presented to the right (ignored) channel: neutral words, rare neutral words and alcohol-related words. The hypothesized information processing bias should cause patients to make disproportionally more shadowing errors in the third condition. An ANOVA revealed a significant condition effect (P < 0.001), a tendency towards a group effect (P = 0.09) and a significant interaction (P < 0.01) in the expected direction. There was a marked increase of errors in alcoholics when disease-related stimuli were presented compared to the neutral conditions and to the controls.

Accumulation of O6- and 7-methylguanine in DNA of N-nitroso-N-methylbenzylamine-treated rats is restricted to non-target organs for N-nitroso-N-methylbenzylamine-induced carcinogenesis

The distribution and accumulation of O6-methylguanine (O6-meGua) and 7-methylguanine (7-meGua) was investigated immunocytochemically in target and non-target tissues of rats injected twice weekly with 0.5 mg N-nitroso-N-methylbenzylamine (NMBzA)/kg for 16.5 weeks. Seventy two hours after every two or three doses, two NMBzA-treated rats and one control rat were killed. Tissue-specific cell proliferation was investigated after two injections of bromodeoxyuridine (BrdU) to rats unexposed to NMBzA. Neither O6-meGua- nor 7-meGua-specific immunostaining could be observed in the target tissues for tumor induction, i.e. esophagus, tongue and forestomach. Accumulation of both O6-meGua and 7-meGua was found, however, in nasal, tracheal and bronchiolar epithelia and glands--tissues for which tumor induction by NMBzA has not been reported. An explanation for this phenomenon might be the relatively low levels of cellular proliferation we observed in the latter epithelia. The present results support the hypothesis that the tumorigenic organotropism of NMBzA is determined both by the level of DNA methylation and the proliferative capacity of the methylated cells.

Immunocytochemical localization of DNA adducts induced by a single dose of N-nitroso-N-methylbenzylamine in target and non-target tissues of tumor formation in the rat

The formation and short-term persistence of O6-methylguanine (O6-meGua) and 7-methylguanine (7-meGua) in individual cells of various target and non-target tissues for tumor induction in rats were examined after a single dose of N-nitroso-N-methylbenzylamine (NMBzA). In the principal target organ, the esophagus, both adducts were observed at 6 h after 0.5, 1.0 and 2.5 mg NMBzA/kg in a dose-dependent manner in nuclei of epithelial cells only. Nuclear staining in this organ had apparently declined by 72 h and modified nuclei were found in the more differentiated cells located closer to the lumen. In epithelial cells of the tongue, another target organ of NMBzA, methylation at 6 h was also dose dependent. At 72 h nuclear staining was lower and again largely located in differentiated cells. In the liver, a non-target organ, O6-meGua was not detectable and 7-meGua-specific staining was weak, being only observed at 6 h after the highest dose. Dose-dependent DNA methylation was seen, both at 6 and 72 h, in other non-target organs such as lung (bronchiolar epithelial cells), trachea (epithelial and glandular cells) and nasal cavity (respiratory epithelial cells, ductal cells of the respiratory lamina propria and cells of Bowman glands of the olfactory lamina propria); the nuclei of the glandular cells were highly methylated. Visual inspection of lung, trachea and nasal cavity indicated no or only minor losses of O6-meGua and 7-meGua between 6 and 72 h. Microdensitometric determination of the nuclear staining at 6 and 72 h indicated that the promutagenic O6-meGua was partially lost from cells of the tongue epithelium but did persist in esophageal epithelial cells; 7-meGua was lost to a substantial extent from both tongue and esophagus. The present results imply that the organotropism of NMBzA is not uniquely determined either by the initial level or the short-term persistence of DNA methylation.

Activation of c-K-ras is frequent in pancreatic carcinomas of Syrian hamsters, but is absent in pancreatic tumors of rats

We have investigated the presence of mutations in ras genes at codons 12, 13 and 61 in chemically induced pancreatic tumors of rats and Syrian hamsters. Mutations were detected by means of allele-specific oligonucleotide hybridization to ras sequences amplified in vitro by the polymerase chain reaction. No mutations were observed in the c-K-ras gene or the c-H-ras gene of nine azaserine-induced adenomas and 15 carcinomas of the rat pancreas. This indicates that activated ras genes are not commonly involved in rat pancreatic cancer evolving from acinar cells. However, in 19 out of 20 ductular adenocarcinomas of hamster pancreas (95%), either codon 12 or 13 of the c-K-ras gene was mutated. This indicates that the activation of c-K-ras is a frequent event in the multistep process of pancreatic carcinogenesis induced by the alkylating carcinogen N-nitrosobis(2-oxopropyl)amine (BOP). The mutations of both codons were G----A transitions of the second base which is consistent with the type of mutation to be expected from DNA alkylation. Activation of the c-K-ras gene, therefore, may not only be a frequent but also an early event in hamster pancreas carcinogenesis. The frequent activation of the c-K-ras gene in both human and hamster pancreatic cancer emphasizes the relevance of BOP-induced pancreatic adenocarcinomas in Syrian hamsters as an experimental model system for studying human pancreatic cancer.

Early indicators of exocrine pancreas carcinogenesis produced by non-genotoxic agents

In the past 40 years the incidence of pancreatic cancer in many Western countries had increased. Since no single factor responsible for the development of pancreatic cancer has been identified, it is believed that non-genotoxic factors may play an important role in the pathogenesis of this highly fatal form of cancer. Focal abnormalities of acinar cells, referred to as atypical acinar cell foci or nodules, occur spontaneously in rats and some other species. Their incidence increases with age from zero at birth to about 75% in 2-year-old rats. These spontaneous lesions have a phenotype that cannot be distinguished from the putative, atypical preneoplastic, acinar cell foci induced in rat pancreas by the carcinogen azaserine. Unsaturated fat (corn oil) has been found to increase the incidence of atypical acinar cell nodules and adenomas in the pancreas of non-carcinogen-treated rats without influencing the weight of the pancreas. Furthermore, unsaturated fat has a specific promoting effect on the growth potential of atypical acinar cell foci and nodules induced in rat pancreas by azaserine, resulting in an increase in the number and size of these lesions. Rats fed raw soya flour or trypsin inhibitors develop an enlarged pancreas as a result of hypertrophy and hyperplasia. They also develop acidophilic atypical acinar cell foci and nodules, adenomas and adenocarcinomas after being fed full-fat raw soya flour for 2 years. It may be concluded from the observations in rat pancreas that non-genotoxic compounds or conditions that enhance pancreatic growth may be classified as non-genotoxic pancreatic tumour promoters. The observations with corn oil, however, indicate that there may be non-genotoxic compounds that specifically enhance growth of spontaneous initiated atypical acinar cell foci without causing hyperplasia of the pancreas. The possible mechanisms whereby unsaturated fat and trypsin inhibitors exert their effects on exocrine pancreatic carcinogenesis are discussed.

Cell specific DNA alkylation in target and non-target organs of N-nitrosobis(2-oxopropyl)amine-induced carcinogenesis in hamster and rat

Tissue-specific formation and short-term persistence of alkylated DNA bases have been studied immunocytochemically in Syrian hamsters and rats killed 3-48 h after a single s.c. or oral dose of N-nitrosobis(2-oxopropyl)amine (BOP). Antisera specific for O6-(m)ethylguanine and for 7-(m)ethylguanine were used. Strong nuclear staining, indicative of a high level of DNA alkylation, was observed at all time points in the intra- and interlobular duct cells and in the centroacinar cells of the hamster pancreas, the main target organ of BOP-induced carcinogenesis. Acinar cells were weakly stained for up to 24 h. In the liver, nuclear staining was strong in all cell types, and more pronounced in the periportal than in the central venous area. Both O6-alkylguanine and 7-alkylguanine preferentially disappeared from the centrilobular area of the liver which is in agreement with the high O6-methyltransferase activity of liver and the unusually high levels of 7-methylguanine DNA glycosylase activity in hamster tissues. Strong staining was observed throughout the experiment in the tubular cells of the renal cortex and in bronchiolar Clara and alveolar type II cells of the lung. The staining intensity of the cells of the thyroid follicles and of the columnar epithelial cells of the colon was moderate. In the rat, nuclear staining was strong in the nasal cavity (Bowman glands), the epithelium lining the thyroid follicles, the lung, liver and in the fibroblasts of the ureter intima and adventitia. The epithelial cell nuclei of the colon and ureter were moderately stained. In the pancreas, staining was weak in acinar, duct and islet cells; no acinar staining remained at 48 h. In the liver, nuclear staining was strong all over the lobule. O6-Alkylguanine was preferentially removed from the centrilobular area. The renal tubular cells were only weakly stained. From the present study we can conclude that--with the exception of hamster kidney and rat liver--high levels of DNA alkylation and stability of the alkylated products were related to a high tumor incidence.

Immunocytochemical visualization of DNA adducts in mouse tissues and human white blood cells following treatment with benzo[a]pyrene or its diol epoxide. A quantitative approach

The formation and stability of benzo[a]pyrene DNA adducts were studied in tissues of BALB/c mice exposed to benzo[a]pyrene (B[a]P). The DNA adducts were visualized with an immunocytochemical peroxidase staining technique using an antiserum specific for the major B[a]P-derived adduct in DNA [(+/-)trans-7,8-dihydroxy-anti-9,10-epoxy-7,8,9,10- tetrahydrobenzo[a]pyrene (BPDE-N2-dG)]. The nuclear staining density was measured by microdensitometry. When mice were treated with an increasing dose of B[a]P the nuclear staining increased in the tissues studied (lung, heart and kidney). A linear relationship was found between the immunocytochemical nuclear staining signal and the actual DNA adduct level in the lung as measured by 32P-postlabeling. Maximum adduct formation was found 5 days after a single i.p. injection of B[a]P. Adduct levels decreased gradually after 7 days, but even after 61 days a slight specific staining was still present, suggesting that not all adducts had disappeared at that time. As judged from the disappearance of [3H]thymidine from prelabeled DNA the loss of adducts from the lung was not a result of DNA repair but one of cell turnover. In human white blood cells B[a]P-derived adducts could be detected after in vitro incubation with the reactive metabolite of B[a]P (BPDE). Dose-response studies demonstrated a positive relationship between BPDE-DNA adduct formation, the immunocytochemical staining signal and the BPDE concentration in the culture medium.

Immunocytochemical analysis of in vivo DNA modification

In the past decades a large number of DNA adducts induced in the intact animal by alkylating agents have been identified. The formation and repair of these adducts are important determinants, not only of mutagenesis, tumor initiation and DNA-mediated toxicity but probably also of tumor progression. Most studies on in vivo DNA modification have been performed on isolated bulk DNA. More recently, methods have been developed to study the distribution of DNA adducts at the level of either the individual gene or the individual cell. This paper reviews immunocytochemical methods to study the formation and repair of DNA adducts and other DNA modifications at the level of the individual cell. DNA modifications induced by alkylating agents and a variety of other agents including ultraviolet radiation, aromatic amines, polycyclic aromatic hydrocarbons and platinum anti-cancer drugs will be discussed. Up to now, immunocytochemical analysis of in vivo modified DNA has largely concentrated on experimental animals. These studies have revealed striking heterogeneities with regard to formation and/or repair of DNA adducts in tissues from rat, hamster and mouse. Immunocytochemical adduct analysis can be used to identify in a convenient, fast and detailed way cell types, cell stages and sites in which biological effects of the adducts might be expressed. More recently, immunocytochemical analysis of DNA adducts also proved to be feasible on in situ exposed human samples. A number of existing and potential applications in the field of chemical carcinogenesis, experimental chemotherapy and molecular epidemiology are discussed.

Bioactivation of N-nitrosomethylbenzylamine and N-nitrosomethyl-amylamine in oesophageal papillomas

Oesophageal papillomas were induced in male F344 rats by continuous exposure to N-nitrosomethylbenzylamine (NMBzA) and N-nitrosomethyl(2-methylbutyl)amine in the drinking water at concentrations of 10 and 19.5 p.p.m. respectively. After 81-141 days animals received a single i.p. chasing dose of NMBzA (0.1 mmol/kg), [14C-methyl]NMBzA or N-nitroso[14C-methyl]amylamine and were killed 6 h later. Induced papillomas (3-9 per animal) were analysed by autoradiography and by immunohistochemistry using a polyclonal antibody to O6-methyldeoxyguanosine. Both techniques revealed the presence of high levels of alkylation products in all papillomas investigated. Immunohistochemical staining of O6-methyldeoxyguanosine was largely restricted to nuclei of the basal layer and of epithelial cells with incipient keratinization. These findings demonstrate that NMBzA and N-nitrosomethylamylamine and probably related methylalkylnitrosamines are effectively bioactivated in premalignant lesions, indicating that during chronic exposure papillomas can acquire additional mutations that are likely to play a major role in tumour progression.

Long-term persistence of DNA alkylation in hamster tissues after N-nitrosobis(2-oxopropyl)amine

The persistence of 7- and O6-alkylation of guanine in DNA of cell nuclei of male Syrian hamster pancreas, liver, kidneys, lungs [target tissues of N-nitrosobis(2-oxopropyl)amine (BOP)] and salivary glands (nontarget tissue) was studied immunocytochemically 6 h, 1, 3, 7, 14, 28, and 56 days after a single s.c. injection of 20 mg BOP/kg. Conventional antisera raised against O6-methylguanine and imidazole-ring-opened 7-methyl-guanine were used. Persistent alkyl-specific staining was observed for up to 7 days (7-alkylguanine) or 56 days (O6-alkylguanine) in inter- and intralobular duct cells and centro-acinar cells of the pancreas, periportal hepatocytes and bile duct cells of the liver, cells of the proximal convoluted tubules of the renal cortex, and bronchiolar Clara and alveolar cells in the lungs. Both adducts disappeared from centrilobular liver cells within 1 day, from pancreatic acinar cells within 3 days, and from ducts and acini of the submandibular salivary glands within 14 days after BOP treatment. A high level of persistent O6-alkylation of guanine was related with a high tumor incidence only in case of the ductal/ductular system of the pancreas, the main target tissue of BOP-induced carcinogenesis. The relatively weak carcinogenicity of BOP in other tissues with long-term persistence of O6-alkylguanine in DNA indicates that the formation and persistence of DNA alkylation are not sufficient to account for the carcinogenic organotropism of BOP. Additional factors, such as cell proliferation, appropriate promoting stimuli and the (onco)genes critically involved, may be as important as the modification of DNA.

Improved immunocytochemical staining of carcinogen-DNA adducts by a capillary slot block system

We developed an immunocytochemical protocol in which incubation occurs in a capillary slot instead of the conventional horizontal drop. Slots of constant width were formed by placing slides on top of each other with parafilm spacer layers in between. Cryostat or semi-thin plastic-embedded sections were cut from organs of carcinogen-treated experimental animals. Carcinogen-DNA adducts were visualized in the affected nuclei by a double peroxidase-antiperoxidase method using rabbit antisera specific for certain DNA adducts formed. The staining in capillary slot blocks offered better staining reproducibility than the conventional method. This is particularly important when the staining intensity must be quantified. In addition, handling of the blocks was substantially less laborious than the individual treatment of slides, making this protocol especially suitable for larger series of slides. Other applications for the capillary slot block protocol should be enzyme histochemistry and in situ hybridization.

Intercellular variation in levels of adducts of aflatoxin B1 and G1 in DNA from rat tissues: a quantitative immunocytochemical study

Adducts between aflatoxin B1 and G1 and DNA have been visualised and quantified in various rat tissues by a sensitive immunocytochemical approach. The quantitative validity of this assay has been examined by comparison with experiments using radioactively labelled aflatoxin. Rats were exposed to single and multiple doses of aflatoxin and a marked intercellular variation in adduct levels was observed in kidney and lung, in contrast to the liver, where binding was more homogeneous. No adducts were detected in the oesophagus, forestomach, colon, spleen or testes (detection limit approximately 300 pg aflatoxin/mg DNA). The DNA adduct data are discussed in relation to the carcinogenicity of aflatoxin B1 and G1.

Kinetics of induction and growth of putative precancerous acinar cell foci in azaserine-induced rat pancreas carcinogenesis

The kinetics of induction and growth of acinar cell lesions has been investigated in rat pancreas after a single dose of the carcinogen azaserine. The time--response relationship was studied in male Wistar-related rats given a single i.p. injection of 30 mg L-azaserine/kg body weight at 18 days of age. Rats were killed between 4 and 78 weeks after treatment and ATPase-stained pancreas sections were quantitatively evaluated for the number and size of acidophilic, ATPase-positive and basophilic, ATPase-deficient foci. The number of acidophilic foci remained constant from 8 weeks onwards, while the number of basophilic foci slightly increased with time. The size of both acidophilic and basophilic foci increased throughout the experimental period. Due to two times higher number/cm3 and faster growth of the acidophilic foci, four times more acidophilic than basophilic focus tissue was present at the end of the experiment. Progression of acidophilic foci to adenomas and carcinomas was occasionally seen at later time points (greater than 34 weeks) in this rat strain. The dose--response relationship was studied in male and female Sprague--Dawley rats given a single i.p. injection of 0-45 mg azaserine/kg body weight at 19 days of age. Rats were autopsied at 17 weeks after treatment, and pancreas sections were quantitatively evaluated after ATPase histochemistry. The relationship between dose and number of foci was linear up to 30 mg/kg azaserine for both acidophilic and basophilic foci in males and females. For each individual dose, the number of foci induced was the same in males and females, and there were two to three times more acidophilic than basophilic foci. The percentage of pancreatic tissue occupied by focus tissue was 1.75 times higher in males, pointing to a higher growth-potential of acidophilic foci in males than in females. The first-order dose--response kinetics indicate that the conversion of a normal acinar cell into a focus-forming cell occurs by one specific azaserine-mediated rare event, occurring probably at the genetic level of the target cell.

Immunocytochemical analysis of O6-alkylguanine shows tissue specific formation in and removal from esophageal and liver DNA in rats treated with methylbenzylnitrosamine, dimethylnitrosamine, diethylnitrosamine and ethylnitrosourea

The formation and repair of carcinogen-DNA adducts in esophagus and liver of rats treated with a single i.p. dose of methylbenzylnitrosamine (MBN), dimethylnitrosamine (DMN), diethylnitrosamine (DEN) or ethylnitrosourea (ENU) has been studied using peroxidase immunocytochemistry to visualize O6-alkylguanine in DNA of individual cells. After MBN O6-methylguanine (O6-MeG) specific nuclear staining was only present in the target tissue for tumor induction, the esophageal epithelium. Part of the adducts persisted for at least 72 h. No O6-MeG could be detected in liver. DEN, a carcinogen in liver and esophagus, led to DNA modification of esophageal epithelial cells, and liver parenchymal and non-parenchymal (Kupffer and sinusoidal) cells of the centrilobular area. O6-EtG was removed within 72 h from both liver cell populations. A similar distribution of adduct (O6-MeG) formation was observed in liver after the hepatocarcinogen DMN, but this nitrosamine did not detectably modify esophageal cells. O6-MeG persisted in Kupffer and especially sinusoidal lining cells of liver, consistent with the induction of sarcomas by DMN. The relatively unspecific, directly alkylating carcinogen ENU modified DNA of all cell types to a similar extent. A qualitative correlation was obtained between the tissue specific ability to induce tumors and the formation of O6-alkylguanine (O6-alkylG). Our experiments support the hypothesis that DNA modification is necessary for the initiation of carcinogenesis by chemical carcinogens, and that a low capacity to repair promutagenic lesions, like O6-alkylG, potentiates this process.

Modulation of putative preneoplastic foci in exocrine pancreas of rats and hamsters. Interaction of dietary fat and coffee

The effects of coffee and dietary fat (alone and in combination) on the development of preneoplastic lesions in exocrine pancreas were investigated in rats and hamsters, treated with azaserine or N-nitrosobis(2-oxopropyl)amine, respectively. The animals were given the respective diets (5% or 25% corn oil) and coffee (instead of drinking water) within one week after the treatment with carcinogen. At four months postinitiation, the pancreata were quantitatively examined for the number and size of preneoplastic foci. In rats, coffee alone inhibited growth of acidophilic foci and, moreover, slightly inhibited the positive modulating effect of fat on growth of these foci, pointing to a negative rather than a positive interaction between these two life-style factors. In hamsters, coffee alone enhanced growth of cystic foci, whereas fat alone enhanced growth of ductular foci. An interaction between fat and coffee on pancreatic carcinogenesis in hamsters could not be demonstrated.

Modulation of dietary fat-promoted pancreatic carcinogenesis in rats and hamsters by chronic ethanol ingestion

The effect of chronic ethanol ingestion on dietary fat-promoted pancreatic carcinogenesis was investigated in rats and hamsters. Rats were given a single i.p. injection of 30 mg azaserine per kg body wt at 19 days of age. Hamsters were injected s.c. with 20 mg N-nitrosobis(2-oxopropyl)amine (BOP) per kg body wt at 6 and 7 weeks of age. The animals were fed a semi-purified diet high in unsaturated fat (25% corn oil) either separately or in combination with ethanol. Ethanol was provided in drinking water at a concentration of 10% (w/v). A separate group maintained on a diet low in unsaturated fat (5% corn oil) was included as extra controls. The rats and hamsters were given their diets and received ethanol via their drinking water after treatment with carcinogen. Terminal autopsy of rats was 15 months after azaserine treatment and of hamsters 12 months after the last injection with BOP. Dietary fat was found to enhance pancreatic carcinogenesis in both rats and hamsters. In rats, ethanol slightly enhanced the multiplicity but not the incidence of malignant tumours, while in hamsters ethanol did not show any modulating effect on dietary fat-promoted carcinogenesis. It was concluded that dietary fat-promoted pancreatic carcinogenesis as observed in the animal models applied is not significantly modulated by chronic ethanol ingestion.

Modulation of dietary fat-promoted pancreatic carcinogenesis in rats and hamsters by chronic coffee ingestion

The effect of chronic coffee ingestion on dietary fat-promoted pancreatic carcinogenesis was investigated in rats and hamsters. Rats were given a single i.p. injection of 30 mg azaserine per kg body weight at 19 days of age. Hamsters were injected s.c. with 20 mg N-nitrosobis(2-oxopropyl)amine (BOP) per kg body weight at 6 and 7 weeks of age. The animals were fed a semi-purified diet high in unsaturated fat (25% corn oil) either in combination with coffee or not. Coffee was provided instead of drinking water. A separate group maintained on a diet low in unsaturated fat (5% corn oil) was included as extra controls. The rats and hamsters were given their diets and coffee after treatment with carcinogen. Terminal autopsy of rats was 15 months after azaserine treatment and of hamsters 12 months after the last injection with BOP. In rat pancreas, the numbers of adenomas and carcinomas were significantly lower in the group maintained on the combination of a high-fat diet and coffee than in the high-fat group without coffee, while in the latter group the number of adenomas and carcinomas had significantly increased as compared to the low-fat controls. In hamsters, the number of ductal/ductular adenocarcinomas had significantly increased in the high-fat group as compared to the low-fat controls. The inhibitory effect of coffee on dietary fat-promoted pancreatic carcinogenesis was also noticed in this species but was less pronounced than in rats. It was concluded that chronic coffee consumption has an inhibitory effect on dietary fat-promoted pancreatic carcinogenesis in rats and hamsters. More research is needed to elucidate the mechanism by which coffee (constituents) modulates carcinogenesis.

[The role of postoperative radiotherapy in the treatment of hypernephroid carcinoma]

The following results can be derived from the clinical and radiobiological literature as well as from the authors's own experiences with 91 patients analyzed retrospectively and evaluated with respect to their risk factors. 1. A postoperative irradiation is very probably sensible in patients with tumor perforation through the renal capsule (T3/T4) and with venous or lymph node manifestations. 2. The operation method is essential, above all the transabdominal technique and the quality of lymph dissection. 3. Prospective studies are necessary in order to clear up the role of radiotherapy in patients with lymph node manifestations and the other two risk factors mentioned in item 1. 4. Further studies on the tumor biology of the hypernephroid carcinoma are necessary in order to gain prognostic criteria allowing a pretherapeutic sensitivity recognition. 5. The effect of a supplementary radiotherapy can be only that of local recurrence prevention in case of a locally advanced tumor and the absence of demonstrable remote metastases. This seems justified, because the local recurrence rate in our own patients was only 3.3%.