The landscape of transcription factor promoter activity during vegetative development in Marchantia

Transcription factors (TFs) are essential for the regulation of gene expression and cell fate determination. Characterising the transcriptional activity of TF genes in space and time is a critical step towards understanding complex biological systems. The vegetative gametophyte meristems of bryophytes share some characteristics with the shoot apical meristems of flowering plants. However, the identity and expression profiles of TFs associated with gametophyte organization are largely unknown. With only ∼450 putative TF genes, Marchantia (Marchantia polymorpha) is an outstanding model system for plant systems biology. We have generated a near-complete collection of promoter elements derived from Marchantia TF genes. We experimentally tested reporter fusions for all the TF promoters in the collection and systematically analysed expression patterns in Marchantia gemmae. This allowed us to build a map of expression domains in early vegetative development and identify a set of TF-derived promoters that are active in the stem cell zone. The cell markers provide additional tools and insight into the dynamic regulation of the gametophytic meristem and its evolution. In addition, we provide an online database of expression patterns for all promoters in the collection. We expect that these promoter elements will be useful for cell-type-specific expression, synthetic biology applications, and functional genomics.

The Polycomb repressive complex 2 deposits H3K27me3 and represses transposable elements in a broad range of eukaryotes

The mobility of transposable elements (TEs) contributes to evolution of genomes. Their uncontrolled activity causes genomic instability; therefore, expression of TEs is silenced by host genomes. TEs are marked with DNA and H3K9 methylation, which are associated with silencing in flowering plants, animals, and fungi. However, in distantly related groups of eukaryotes, TEs are marked by H3K27me3 deposited by the Polycomb repressive complex 2 (PRC2), an epigenetic mark associated with gene silencing in flowering plants and animals. The direct silencing of TEs by PRC2 has so far only been shown in one species of ciliates. To test if PRC2 silences TEs in a broader range of eukaryotes, we generated mutants with reduced PRC2 activity and analyzed the role of PRC2 in extant species along the lineage of Archaeplastida and in the diatom P. tricornutum. In this diatom and the red alga C. merolae, a greater proportion of TEs than genes were repressed by PRC2, whereas a greater proportion of genes than TEs were repressed by PRC2 in bryophytes. In flowering plants, TEs contained potential cis-elements recognized by transcription factors and associated with neighbor genes as transcriptional units repressed by PRC2. Thus, silencing of TEs by PRC2 is observed not only in Archaeplastida but also in diatoms and ciliates, suggesting that PRC2 deposited H3K27me3 to silence TEs in the last common ancestor of eukaryotes. We hypothesize that during the evolution of Archaeplastida, TE fragments marked with H3K27me3 were selected to shape transcriptional regulation, controlling networks of genes regulated by PRC2.

MarpolBase Expression: A Web-Based, Comprehensive Platform for Visualization and Analysis of Transcriptomes in the Liverwort Marchantia polymorpha

The liverwort Marchantia polymorpha is equipped with a wide range of molecular and genetic tools and resources that have led to its wide use to explore the evo-devo aspects of land plants. Although its diverse transcriptome data are rapidly accumulating, there is no extensive yet user-friendly tool to exploit such a compilation of data and to summarize results with the latest annotations. Here, we have developed a web-based suite of tools, MarpolBase Expression (MBEX, https://marchantia.info/mbex/), where users can visualize gene expression profiles, identify differentially expressed genes, perform co-expression and functional enrichment analyses and summarize their comprehensive output in various portable formats. Using oil body biogenesis as an example, we demonstrated that the results generated by MBEX were consistent with the published experimental evidence and also revealed a novel transcriptional network in this process. MBEX should facilitate the exploration and discovery of the genetic and functional networks behind various biological processes in M. polymorpha and promote our understanding of the evolution of land plants.

The renaissance and enlightenment of Marchantia as a model system

The liverwort Marchantia polymorpha has been utilized as a model for biological studies since the 18th century. In the past few decades, there has been a Renaissance in its utilization in genomic and genetic approaches to investigating physiological, developmental, and evolutionary aspects of land plant biology. The reasons for its adoption are similar to those of other genetic models, e.g. simple cultivation, ready access via its worldwide distribution, ease of crossing, facile genetics, and more recently, efficient transformation, genome editing, and genomic resources. The haploid gametophyte dominant life cycle of M. polymorpha is conducive to forward genetic approaches. The lack of ancient whole-genome duplications within liverworts facilitates reverse genetic approaches, and possibly related to this genomic stability, liverworts possess sex chromosomes that evolved in the ancestral liverwort. As a representative of one of the three bryophyte lineages, its phylogenetic position allows comparative approaches to provide insights into ancestral land plants. Given the karyotype and genome stability within liverworts, the resources developed for M. polymorpha have facilitated the development of related species as models for biological processes lacking in M. polymorpha.

Liverwort oil bodies: diversity, biochemistry, and molecular cell biology of the earliest secretory structure of land plants

Liverworts are known for their large chemical diversity. Much of this diversity is synthesized and enclosed within oil bodies (OBs), a synapomorphy of the lineage. OBs contain the enzymes to biosynthesize and store large quantities of sesquiterpenoids and other compounds while limiting their cytotoxicity. Recent important biochemical and molecular discoveries related to OB formation, diversity, and biochemistry allow comparison with other secretory structures of land plants from an evo-devo perspective. This review addresses and discusses the most recent advances in OB origin, development, and function towards understanding the importance of these organelles in liverwort physiology and adaptation to changing environments. Our mapping of OB types and chemical compounds to the current liverwort phylogeny suggests that OBs were present in the most recent common ancestor of liverworts, supporting that OBs evolved as the first secretory structures in land plants. Yet, we require better sampling to define the macroevolutionary pattern governing the ancestral type of OB. We conclude that current efforts to find molecular mechanisms responsible for the morphological and chemical diversity of secretory structures will help understand the evolution of each major group of land plants, and open new avenues in biochemical research on bioactive compounds in bryophytes and vascular plants.

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The eLife Early-Career Advisory Group discusses eLife's new peer review and publishing model, and how the whole process of scientific communication could be improved for the benefit of early-career researchers and the entire scientific community.

Molecular mechanisms involved in functional macroevolution of plant transcription factors

Transcription factors (TFs) are key components of the transcriptional regulation machinery. In plants, they accompanied the evolution from unicellular aquatic algae to complex flowering plants that dominate the land environment. The adaptations of the body plan and physiological responses required changes in the biological functions of TFs. Some ancestral gene regulatory networks are highly conserved, while others evolved more recently and only exist in particular lineages. The recent emergence of novel model organisms provided the opportunity for comparative studies, producing new insights to infer these evolutionary trajectories. In this review, we comprehensively revisit the recent literature on TFs of nonseed plants and algae, focusing on the molecular mechanisms driving their functional evolution. We discuss the particular contribution of changes in DNA-binding specificity, protein-protein interactions and cis-regulatory elements to gene regulatory networks. Current advances have shown that these evolutionary processes were shaped by changes in TF expression pattern, not through great innovation in TF protein sequences. We propose that the role of TFs associated with environmental and developmental regulation was unevenly conserved during land plant evolution.

The Intrinsically Disordered Protein CARP9 Bridges HYL1 to AGO1 in the Nucleus to Promote MicroRNA Activity

In plants, small RNAs are loaded into ARGONAUTE (AGO) proteins to fulfill their regulatory functions. MicroRNAs (miRNAs), one of the most abundant classes of endogenous small RNAs, are preferentially loaded into AGO1. Such loading, long believed to happen exclusively in the cytoplasm, was recently proposed to also occur in the nucleus. Here, we identified CONSTITUTIVE ALTERATIONS IN THE SMALL RNAS PATHWAYS9 (CARP9), a nuclear-localized, intrinsically disordered protein, as a factor promoting miRNA activity in Arabidopsis (Arabidopsis thaliana). Mutations in the CARP9-encoding gene led to a mild reduction of miRNAs levels, impaired gene silencing, and characteristic morphological defects, including young leaf serration and altered flowering time. Intriguingly, we found that CARP9 was able to interact with HYPONASTIC LEAVES1 (HYL1), but not with other proteins of the miRNA biogenesis machinery. In the same way, CARP9 appeared to interact with mature miRNA, but not with primary miRNA, positioning it after miRNA processing in the miRNA pathway. CARP9 was also able to interact with AGO1, promoting its interaction with HYL1 to facilitate miRNA loading in AGO1. Plants deficient in CARP9 displayed reduced levels of AGO1-loaded miRNAs, partial retention of miRNA in the nucleus, and reduced levels of AGO1. Collectively, our data suggest that CARP9 might modulate HYL1-AGO1 cross talk, acting as a scaffold for the formation of a nuclear post-primary miRNA-processing complex that includes at least HYL1, AGO1, and HEAT SHOCK PROTEIN 90. In such a complex, CARP9 stabilizes AGO1 and mature miRNAs, allowing the proper loading of miRNAs in the effector complex.

Evolutionary history of HOMEODOMAIN LEUCINE ZIPPER transcription factors during plant transition to land

Plant transition to land required several regulatory adaptations. The mechanisms behind these changes remain unknown. Since the evolution of transcription factors (TFs) families accompanied this transition, we studied the HOMEODOMAIN LEUCINE ZIPPER (HDZ) TF family known to control key developmental and environmental responses. We performed a phylogenetic and bioinformatics analysis of HDZ genes using transcriptomic and genomic datasets from a wide range of Viridiplantae species. We found evidence for the existence of HDZ genes in chlorophytes and early-divergent charophytes identifying several HDZ members belonging to the four known classes (I-IV). Furthermore, we inferred a progressive incorporation of auxiliary motifs. Interestingly, most of the structural features were already present in ancient lineages. Our phylogenetic analysis inferred that the origin of classes I, III, and IV is monophyletic in land plants in respect to charophytes. However, class IIHDZ genes have two conserved lineages in charophytes and mosses that differ in the CPSCE motif. Our results indicate that the HDZ family was already present in green algae. Later, the HDZ family expanded accompanying critical plant traits. Once on land, the HDZ family experienced multiple duplication events that promoted fundamental neo- and subfunctionalizations for terrestrial life.

Arabidopsis thaliana homeodomain-leucine zipper type I transcription factors contribute to control leaf venation patterning

Venation patterning is a taxonomic attribute for classification of plants and it also plays a role in the interaction of plants with the environment. Despite its importance, the molecular physiology controlling this aspect of plant development is still poorly understood. Auxin plays a central role modulating the final vein network and patterning. This addendum discusses recent findings on the role of homeodomain-leucine zipper (HD-Zip) transcription factors on the regulation of leaf venation patterning. Moreno-Piovano et al. reported that ectopic expression of a sunflower HD-Zip I gene, HaHB4, increased the asymmetry of leaf venation. Even more, this work showed that auxin transport in the leaf through LAX carriers controls venation patterning. Here, we provide evidence indicating that some Arabidopsis thaliana HD-Zip I genes play a role in the determination of the final leaf venation patterning. We propose that these genes contribute to regulate vein patterning, likely controlling auxin homeostasis.

Co-expression and Transcriptome Analysis of Marchantia polymorpha Transcription Factors Supports Class C ARFs as Independent Actors of an Ancient Auxin Regulatory Module

We performed differential gene expression (DGE) and co-expression analyses with genes encoding components of hormonal signaling pathways and the ∼400 annotated transcription factors (TFs) of M. polymorpha across multiple developmental stages of the life cycle. We identify a putative auxin-related co-expression module that has significant overlap with transcripts induced in auxin-treated tissues. Consistent with phylogenetic and functional studies, the class C ARF, MpARF3, is not part of the auxin-related co-expression module and instead is associated with transcripts enriched in gamete-producing gametangiophores. We analyze the Mparf3 and MpmiR160 mutant transcriptomes in the context of coexpression to suggest that MpARF3 may antagonize the reproductive transition via activating the MpMIR11671 and MpMIR529c precursors whose encoded microRNAs target SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE (SPL) transcripts of MpSPL1 and MpSPL2. Both MpSPL genes are part of the MpARF3 co-expression group corroborating their functional significance. We provide evidence of the independence of MpARF3 from the auxin-signaling module and provide new testable hypotheses on the role of auxin-related genes in patterning meristems and differentiation events in liverworts.

A matter of quantity: Common features in the drought response of transgenic plants overexpressing HD-Zip I transcription factors

Plant responses to water deficit involve complex molecular mechanisms in which transcription factors have key roles. Previous reports ectopically overexpressed a few members of the homeodomain-leucine zipper I (HD-Zip I) family of transcription factors from different species, and the obtained transgenic plants exhibited drought tolerance which extent depended on the level of overexpression, triggering diverse molecular and physiological pathways. Here we show that most HD-Zip I genes are regulated by drought in the vegetative and/or reproductive stages. Moreover, uncharacterized members of this family were expressed as transgenes both in Col-0 and rdr6-12 backgrounds and were able to enhance drought tolerance in host plants. The extent of such tolerance depended on the expression level of the transgene and was significantly higher in transgenic rdr6-12 than in Col-0. Comparative transcriptome analyses of Arabidopsis thaliana plants overexpressing HD-Zip I proteins indicated that many members have common targets. Moreover, the water deficit tolerance exhibited by these plants is likely due to the induction and repression of certain of these common HD-Zip I-regulated genes. However, each HD-Zip I member regulates other pathways, which, in some cases, generate differential and potentially undesirable traits in addition to drought tolerance. In conclusion, only a few members of this family could become valuable tools to improve drought-tolerance.

Nicotine and cotinine affect the release of vasoactive factors by trophoblast cells and human umbilical vein endothelial cells

OBJECTIVE

To examine nicotine (N) and cotinine (C) effects on trophoblast cells (TCs) and human umbilical vein endothelial cells (HUVEC) secretion of soluble fms-like tyrosine kinase (sFlt-1), soluble endoglin (sENG), placental growth factor (PlGF), transforming growth factor-beta (TGF-beta) and vascular endothelial growth factor (VEGF).

STUDY DESIGN

Human placentas and umbilical cords were collected from uncomplicated pregnancies at term from a total of 24 non-smoking women with a history of normal blood pressure. TCs and HUVEC were cultured for 24 h with C or N (from 10(-12) to 10(-7) M).

MAIN OUTCOME MEASURES

sFlt-1, sENG, PlGF, TGF-beta and VEGF release and messenger RNA (mRNA) expression were evaluated by ELISA and real-time polymerase chain reaction (PCR), respectively.

RESULTS

N and C reduced sFlt-1, sENG and PlGF release by TCs and TGF-beta release by HUVEC. Conversely, N and C increased PlGF secretion, while N alone increased sFlt-1 release by HUVEC. N and C were able to modulate VEGF mRNA expression in HUVEC.

CONCLUSIONS

Our results suggest that N and C affect the balance of some important vasoactive factors released by TCs and HUVEC. This might be one of the possible mechanism through which smoke reduces the risk of hypertensive disorders during pregnancy as well as contributes to the well known detrimental effects of smoking on fetal development.

Characterization of a 2D ion chamber array for the verification of radiotherapy treatments

In this study we investigated the characteristics of a commercial ion chamber array and its performance in the verification of radiotherapy plans. The device was the 2D Array Seven29 model (PTW, Freiburg, Germany). This is a two-dimensional detector array with 729 ionization chambers uniformly arranged in a 27 x 27 matrix with an active area of 27 x 27 cm(2). The detector short-, medium- and long-term reproducibility have been tested through an extensive set of repeated measurements. Short-term reproducibility was well within 0.2%. Medium- and long-term reproducibility were within 1%, including set-up reproducibility errors and linac output fluctuations. Dose linearity was also assessed. The system response to dose was verified to be linear within the range 2-500 MU. Output factors matched very well pinpoint chamber measurements performed in the same experimental conditions with a maximum local percentage difference of 0.4%. Furthermore, the 2D Array sensitivity to millimetric collimator positional changes and to perturbation effect of irradiated area was tested. The comparison with ion chamber data carried out in water was very satisfying. Finally, measurements of wedge-modulated fields and IMRT beam sequence matched very well ion chamber dose profiles acquired in a water tank. The extensive tests performed in this investigation show that the 2D Array Seven29 is a reliable and accurate dosimeter and that it could be a useful tool for the quality assurance and the verification of radiotherapy plans.

Denitrification in tertiary filtration: application of an up-flow filter

The present paper shows the results obtained through an experimental work performed at the wastewater treatment plant of Rome, aimed at studying the performances of a tertiary filter regarding combined removal of suspended solids, COD, and nitrates. The up-flow sand filter was fed by the effluent coming from the secondary settling tank of the plant. The filter bed height was of 80 cm of silica sand. After a start up period, a study of particulate and soluble COD removal process was made, to establish the need of methanol in the denitrification process. Total COD removal efficiency was 60% on average, 55% due by soluble COD removal and 5% by particulate one. In the last phase of the experimental activity methanol was fed as carbon source, sodium sulfite was supplied to produce anoxic environment within the filter and the denitrification efficiency was studied. Nitrates removal rates after an acclimation period of 10 days increased up to 60%, with an effluent NO3-N of 8 mg/L. Denitrification rate was 2.4 kg/m3 d for water temperatures of 25 degrees C. Regarding methanol demand and biologic kinetics, the biomass yield coefficient was 0.3 kg(COD-X)/kg(me). Consequently 2.7 kg of methanol was required per kilogram of denitrified nitrogen.

Prospective randomized trial of steroid withdrawal in liver transplant patients: preliminary report

Although steroid withdrawal has been successfully performed in heart and kidney transplant recipients, no controlled studies of SW have been carried out in liver transplant patients. To evaluate this possibility a prospective controlled study was carried out in 46 liver transplant recipients operated on after may 1991. They all received a sequential quadruple immunosuppression consisting of 3 mg/kg antithymocyte globulins (RATG) for the first 5 postoperative days, cyclosporin A (starting from day 3-5 and maintaining parenteral whole-blood trough levels at 200-300 ng/ml during the first month and at 150-250 thereafter), azathioprine (1 mg/kg per day for the first month) and steroids. Prednisone was started at a dose of 200 mg per day 1 and then tapered to 20 mg/day over the first posteroperative week; this dose was maintained until day 90 when the patients were randomly allocated either to long-term steroid therapy (0.1 mg/kg per day) or to steroid withdrawal. Minimum follow-up after randomization was 6 months (6-27 months). Liver biochemistry was checked at regular intervals throughout the follow-up period. Liver biopsies were performed whenever clinically indicated and also in the first 19 patients during readmission for annual review. The incidence ot acute and chronic rejection 90 days from liver transplantation was 2.5% in patients maintained on long-term therapy. No patient in the steroid-withdrawal group had experienced either an acute or a chronic rejection episode so far. Steroid-related complications did not differ significantly between the two groups. The most recent interim analysis showed that steroid withdrawal is a safe undertaking in liver transplant recipients and may be successfully accomplished in almost all patients.

[Carotid stenosis with contralateral occlusion. Surgical indications and results]

Recent American and European trials have clearly defined that surgery provides best treatment for unilateral critical stenosis of internal carotid artery. Isolated reports seem to confirm this trend also in cases with carotid critical stenosis with controlateral occlusion, even if a major surgical risk may be expected. In our experience in the last two years, out of 96 carotid enderterectomies 20 presented a controlateral occlusion. After routine pre-operative assessment, with particular regard to DSA "cross-filling" study, intervention has been performed under general anesthesia with BP+EEG cerebral monitoring in both groups of patients. In the non occluded group temporary shunt has been used in 19.7% of cases, in occluded the incident of shunting was 40%. Operative morbidity and mortality in the second group was surprisingly absent, with cumulative 4.1% complication rate. Our experience confirms that risks and results in carotid endoarterectomy are similar in both groups of patients.

The role of transplantation in small hepatocellular carcinoma complicating cirrhosis of the liver

Of 176 hepatic transplants performed from 1986 to December 1992, 27 patients had small hepatocellular carcinoma (< or = 5 centimeters) complicating cirrhosis of the liver. All patients were asymptomatic for the hepatic malignancy and the diagnosis was established in each instance preoperatively by means of serial sonographic scans and alpha-fetoprotein levels. Cirrhosis was classified as Child's A in eight instances, as Child's B in 16 and Child C's in three. The cause was alcoholic in three patients, posthepatitic in 21 patients (eight hepatitis B virus [HBV] positive and 13 hepatitis C virus [HCV] positive) and undetermined in three. The in-hospital mortality rate was 11 percent (three of 27). Additionally, five patients died at different intervals after transplantation: only two died of neoplastic recurrence at 12 and 32 months, respectively (7.4 percent rate). Actuarial survival rates were 82 percent at one year and 71 percent at three years, with a mean follow-up period of 32 months (range six to 78 months). Morbidity related to the procedure was a relevant problem: 21 percent of the patients had prompt resumption of normal life while 37 percent required repeated hospitalization and 42 percent required strict control on an outpatient basis. The most frequent problem was HBV or HCV reinfection of the grafted liver, which occurred in 42 percent. Based on this experience, transplantation of the liver has shown an excellent oncologic accuracy for small hepatocellular carcinoma in cirrhosis of the liver, thus representing the most rational surgical procedure for patients with Child's B and Child's C cirrhosis classification. The relevant mortality and morbidity rates, strictly related to this procedure, suggest other options as more appropriate in those with Child A cirrhosis at this time.

Dysarthria and cerebellar ataxia: late occurrence of severe neurotoxicity in a liver transplant recipient

Neurological complications of cyclosporin (CyA) therapy are frequent, usually occurring within the 1st month after transplantation. Though leukoencephalopathy is one of them, it is rarely documented. Here we report the case of an anti-HCV-positive patient with cirrhosis who underwent liver transplantation and developed cyclosporin-induced leukoencephalopathy. The presenting symptoms were dysarthria, difficulty walking, and dysphagia. They were first noted 6 months after transplantation in association with an episode of recurrent HCV acute hepatitis. White matter abnormalities were evident on computed tomography (CT) scanning and magnetic resonance (MR) imaging. This condition improved to some degree after cyclosporin withdrawal. To our knowledge this is the second reported case of CyA neurotoxicity occurring late after liver transplantation. Moreover, the association with acute hepatitis suggests the possibility of graft dysfunction as a contributing and triggering factor.

Liver transplantation for small HCC in cirrhosis

Segmental liver resection is generally considered the treatment of choice for small HCC in cirrhotic livers. Although in selected patients with small encapsulated nodules and low alpha-fetoprotein levels long-term survival can be expected after resection, Western experience is still limited, and follow-up studies too short so that the data presently available cannot be considered satisfactory. The true value of alcoholization as a possible alternative therapy in these patients is still to be ascertained. When using these treatment modalities, the major problem is the high tumour recurrence within the liver. Three main reasons could explain these clinical observations: 1. inadequate resection of the original tumor; 2. unrecognized multifocal HCC; 3. newly generated tumours in the remnant cirrhotic parenchyma. The rationale for liver transplantation is the oncological accuracy of the ablation of the liver, and the possibility of a simultaneous cure of the associated cirrhosis. In our programme of liver transplantation, begun in 1985, we accepted as an indication small HCC in cirrhotic livers. We present here our initial experience with 19 cases.

Somatomedin C (IGF I) plasma levels after orthotopic liver transplantation (OLT) in end-stage cirrhotic patients

Insulin-like growth factors [IGF I and II or somatomedins (SMS)] are polypeptides chemically and biologically correlated with insulin. The main source of synthetic activity and secretion is the liver, although many other tissues have been demonstrated to synthesize SMS. In the circulation, they are not present in a free form, but are mostly bound to a specific carrier protein independently synthesized in the liver. Hepatic or extrahepatic storage organs have not been demonstrated; the half life of the SMS-binding protein complex is between 3 and 4. Synthesis of SMS is regulated by GH, insulin, thyroxine and nutrition (caloric and protein intake, and nitrogen balance). The role of corticosteroids is still a matter of debate: in patients treated with steroids SMS blood levels have been shown to be within normal limits, while biological activity has been demonstrated to be significantly reduced by SMS inhibitors, probably induced by corticosteroid therapy. The biological properties of SMS are related to their structural homology with insulin, and can be summarized as follows: A. Insulin-like activity (glucose oxidation, lipogenesis, glycogen synthesis, inhibition of lipolysis and glycogenolysis); B. Sulphation activity (incorporation of sulphate and leucine into glycosaminglycans of the cartilage); C. Stimulation of fibroblast multiplication; D. Amplification of other hormone activities (GH); E. Complementary anabolic activity with insulin. Low levels of SMS have been demonstrated in hypopituitarism (secondary) or in other diseases independent of GH reduced secretion (primary) such as malnutrition, malabsorption, acute or chronic liver failure and uraemia. Negative nitrogen balance, hypocaloric and/or low protein diets are usually correlated with low levels of SMS. Recently, Schalch et al. reported on the role of orthotopic liver transplantation (OLT) in normalizing SMS blood levels in a group of end-stage liver diseased patients. This preliminary paper deals with changes in IGF-I plasma levels (somatomedin C) in a group of patients affected by end-stage liver cirrhosis before and after OLT.

Reappraisal of surgical treatment of small hepatocellular carcinomas in cirrhosis: clinicopathological study of resection or transplantation

Thirty-two patients with hepatocellular carcinoma (HCC) occurring in individuals with cirrhosis had a potentially curative surgical procedure. Twenty-two had segmental hepatic resections (HR), and 10 underwent orthotopic liver transplantation (OLTx). The diagnosis of hepatic malignancy was established in each case preoperatively, and each case was studied intraoperatively by means of sonography. Postoperatively each surgical specimen was examined pathologically with attention to the possibility of intrahepatic tumor spread. Twenty-three of the 32 patients had single small HCC lesion (less than 5 cm diameter) identified preoperatively. Sixteen of these underwent HR and seven underwent OLTx. Multiple additional neoplastic lesions were found in 19% of the 16 HR cases and in 14% of those undergoing OLTx when the resection specimens were examined pathologically. Vascular invasion was present in 43% of the OLTx patients and in 25% of the HR patients. Subtotal hepatic resection for small HCC occurring in cirrhosis has produced few long-term survivals. Both pre- and intraoperative sonography have been shown to underestimate the extent and distribution of these tumors. Based upon this experience that (1) vascular spread occurs often in HCC and (2) a high risk of postoperative hepatic failure can be expected after HR in cirrhotic individuals, OLTx is the most rational surgical procedure for such cases as it has the potential to cure.

Characterization by morphometric model of liver regeneration in the rat

A new stereological approach to the study of liver regeneration in the rat is described. The method employs a morphometric model consisting of number and size, as well as surface and volume fractions of hepatocytes, their nuclei, cytoplasm, and their relation to the sinusoidal bed. With this technique, it was found that 8 hr after partial hepatectomy, the number of nuclei increased as did the nucleus/cytoplasm ratio, suggesting an early hyperplastic phase. These data, which have not been reported in other studies, underline the importance of evaluating the complex phenomenon of liver regeneration using a stereological approach, which is more representative of all morphometric changes occurring inside and outside the hepatocyte.