Expanded phenotypic spectrum of neurodevelopmental and neurodegenerative disorder Bryant-Li-Bhoj syndrome with 38 additional individuals

Bryant-Li-Bhoj syndrome (BLBS), which became OMIM-classified in 2022 (OMIM: 619720, 619721), is caused by germline variants in the two genes that encode histone H3.3 (H3-3A/H3F3A and H3-3B/H3F3B) [1-4]. This syndrome is characterized by developmental delay/intellectual disability, craniofacial anomalies, hyper/hypotonia, and abnormal neuroimaging [1, 5]. BLBS was initially categorized as a progressive neurodegenerative syndrome caused by de novo heterozygous variants in either H3-3A or H3-3B [1-4]. Here, we analyze the data of the 58 previously published individuals along 38 unpublished, unrelated individuals. In this larger cohort of 96 people, we identify causative missense, synonymous, and stop-loss variants. We also expand upon the phenotypic characterization by elaborating on the neurodevelopmental component of BLBS. Notably, phenotypic heterogeneity was present even amongst individuals harboring the same variant. To explore the complex phenotypic variation in this expanded cohort, the relationships between syndromic phenotypes with three variables of interest were interrogated: sex, gene containing the causative variant, and variant location in the H3.3 protein. While specific genotype-phenotype correlations have not been conclusively delineated, the results presented here suggest that the location of the variants within the H3.3 protein and the affected gene (H3-3A or H3-3B) contribute more to the severity of distinct phenotypes than sex. Since these variables do not account for all BLBS phenotypic variability, these findings suggest that additional factors may play a role in modifying the phenotypes of affected individuals. Histones are poised at the interface of genetics and epigenetics, highlighting the potential role for gene-environment interactions and the importance of future research.

NeuroTri2-VISDOT: An open-access tool to harness the power of second trimester human single cell data to inform models of Mendelian neurodevelopmental disorders

Whole exome and genome sequencing, coupled with refined bioinformatic pipelines, have enabled improved diagnostic yields for individuals with Mendelian conditions and have led to the rapid identification of novel syndromes. For many Mendelian neurodevelopmental disorders (NDDs), there is a lack of pre-existing model systems for mechanistic work. Thus, it is critical for translational researchers to have an accessible phenotype- and genotype-informed approach for model system selection. Single-cell RNA sequencing data can be informative in such an approach, as it can indicate which cell types express a gene of interest at the highest levels across time. For Mendelian NDDs, such data for the developing human brain is especially useful. A valuable single-cell RNA sequencing dataset of the second trimester developing human brain was produced by Bhaduri et al in 2021, but access to these data can be limited by computing power and the learning curve of single-cell data analysis. To reduce these barriers for translational research on Mendelian NDDs, we have built the web-based tool, Neurodevelopment in Trimester 2 - VIsualization of Single cell Data Online Tool (NeuroTri2-VISDOT), for exploring this single-cell dataset, and we have employed it in several different settings to demonstrate its utility for the translational research community.

TBCK syndrome: a rare multi-organ neurodegenerative disease

TBCK syndrome is an autosomal recessive disorder primarily characterized by global developmental delay, hypotonia, abnormal magnetic resonance imaging (MRI), and distinctive craniofacial phenotypes. High variability is observed among affected individuals and their corresponding variants, making clinical diagnosis challenging. Here, we discuss recent breakthroughs in clinical considerations, TBCK function, and therapeutic development.

Genome-wide pooled CRISPR screening in neurospheres

Spheroid culture systems have allowed in vitro propagation of cells unable to grow in canonical cell culturing conditions, and may capture cellular contexts that model tumor growth better than current model systems. The insights gleaned from genome-wide clustered regularly interspaced short palindromic repeat (CRISPR) screening of thousands of cancer cell lines grown in conventional culture conditions illustrate the value of such CRISPR pooled screens. It is clear that similar genome-wide CRISPR screens of three-dimensional spheroid cultures will be important for future biological discovery. Here, we present a protocol for genome-wide CRISPR screening of three-dimensional neurospheres. While many in-depth protocols and discussions have been published for more typical cell lines, few detailed protocols are currently available in the literature for genome-wide screening in spheroidal cell lines. For those who want to screen such cell lines, and particularly neurospheres, we provide a step-by-step description of assay development tests to be performed before screening, as well as for the screen itself. We highlight considerations of variables that make these screens distinct from, or similar to, typical nonspheroid cell lines throughout. Finally, we illustrate typical outcomes of neurosphere genome-wide screens, and how neurosphere screens typically produce slightly more heterogeneous signal distributions than more canonical cancer cell lines. Completion of this entire protocol will take 8-12 weeks from the initial assay development tests to deconvolution of the sequencing data.

Abstract 3562: Dissecting mechanisms underlying FOXR2-mediated gliomagenesis in diffuse midline gliomas

Background: Diffuse midline gliomas (DMGs) are a universally fatal brain tumor of childhood. While histone mutations are a critical tumor initiating event, they are insufficient to drive gliomagenesis. Histone mutations co-occur with somatic alterations in other pathways including TP53, MAPK, and MYC signaling. However, the mechanisms through which these pathways are activated have not been fully elucidated.

Methods: We applied an integrative approach using transcriptomics, epigenetics, proteomics, in vitro cancer models, and in vivo mouse models to systematically evaluate how FOXR2 mediates gliomagenesis.

Results: We have recently found that a subset of DMGs aberrantly express FOXR2, a forkhead transcription factor. FOXR2 is both sufficient to enhance tumor formation, and necessary for FOXR2-expressing DMGs. While FOXR2 indeed enhances MYC protein stability, FOXR2 exerts oncogenesis through MYC-independent functions and specifically hijacks E26-transformation specific (ETS) transcriptional circuits and FOXR2 DNA-binding is highly enriched at ETS motifs. We have performed proteomic and phospho-proteomic analysis of FOXR2-expressing human neural stem cells to identify proteins and phospho-sites that are highly enriched in FOXR2-expressing cells.

Conclusion: Taken together, this study elucidates how FOXR2 interacts with ETS transcription factors to mediate oncogenesis, and further highlights a role for FOXR2 in activating ETS and MAPK signaling.

Citation Format: Jessica W. Tsai, Paloma Cejas, Marissa Coppola, Dayle K. Wang, Smruti Patel, David W. Wu, Phonepasong Arounleut, Xin Wei, Ningxuan Zhou, Sudeepa Syamala, Frank P. Dubois, Kristine Pelton, Jayne Vogelzang, Cecilia Sousa, Audrey Baguette, Xiaolong Chen, Alexandra L. Condurat, Sarah E. Dixon-Clarke, Annarah Charles, Kevin N. Zhou, Sophie D. Lu, Elizabeth M. Gonzalez, Madison S. Chacon, Jeromy J. Digiacomo, Rushil Kumbhani, Dana Novikov, Maria Tsoli, David S. Ziegler, Uta Dirksen, Natalie Jager, Gnana Prakash Balasubramanian, Christof M. Kramm, Michaela Nathrath, Stefan Bielack, Suzanne J. Baker, Jinghui Zhang, James M. McFarland, Gad Getz, Francois Aguet, Nada Jabado, Olaf Witt, Stefan M. Pfister, Keith L. Ligon, Volker Hovestadt, Claudia Kleinman, Henry Long, David T. Jones, Pratiti Bandopadhayay, Timothy N. Phoenix. Dissecting mechanisms underlying FOXR2-mediated gliomagenesis in diffuse midline gliomas. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3562.

FOXR2 Is an Epigenetically Regulated Pan-Cancer Oncogene That Activates ETS Transcriptional Circuits

Forkhead box R2 (FOXR2) is a forkhead transcription factor located on the X chromosome whose expression is normally restricted to the testis. In this study, we performed a pan-cancer analysis of FOXR2 activation across more than 10,000 adult and pediatric cancer samples and found FOXR2 to be aberrantly upregulated in 70% of all cancer types and 8% of all individual tumors. The majority of tumors (78%) aberrantly expressed FOXR2 through a previously undescribed epigenetic mechanism that involves hypomethylation of a novel promoter, which was functionally validated as necessary for FOXR2 expression and proliferation in FOXR2-expressing cancer cells. FOXR2 promoted tumor growth across multiple cancer lineages and co-opted ETS family transcription circuits across cancers. Taken together, this study identifies FOXR2 as a potent and ubiquitous oncogene that is epigenetically activated across the majority of human cancers. The identification of hijacking of ETS transcription circuits by FOXR2 extends the mechanisms known to active ETS transcription factors and highlights how transcription factor families cooperate to enhance tumorigenesis.

SIGNIFICANCE

This work identifies a novel promoter that drives aberrant FOXR2 expression and delineates FOXR2 as a pan-cancer oncogene that specifically activates ETS transcriptional circuits across human cancers. See related commentary by Liu and Northcott, p. 2977.

PPM1D mutations are oncogenic drivers of de novo diffuse midline glioma formation

The role of PPM1D mutations in de novo gliomagenesis has not been systematically explored. Here we analyze whole genome sequences of 170 pediatric high-grade gliomas and find that truncating mutations in PPM1D that increase the stability of its phosphatase are clonal driver events in 11% of Diffuse Midline Gliomas (DMGs) and are enriched in primary pontine tumors. Through the development of DMG mouse models, we show that PPM1D mutations potentiate gliomagenesis and that PPM1D phosphatase activity is required for in vivo oncogenesis. Finally, we apply integrative phosphoproteomic and functional genomics assays and find that oncogenic effects of PPM1D truncation converge on regulators of cell cycle, DNA damage response, and p53 pathways, revealing therapeutic vulnerabilities including MDM2 inhibition.

Topologically protected superconducting ratchet effect generated by spin-ice nanomagnets

We have designed, fabricated and tested a robust superconducting ratchet device based on topologically frustrated spin ice nanomagnets. The device is made of a magnetic Co honeycomb array embedded in a superconducting Nb film. This device is based on three simple mechanisms: (i) the topology of the Co honeycomb array frustrates in-plane magnetic configurations in the array yielding a distribution of magnetic charges which can be ordered or disordered with in-plane magnetic fields, following spin ice rules; (ii) the local vertex magnetization, which consists of a magnetic half vortex with two charged magnetic Néel walls; (iii) the interaction between superconducting vortices and the asymmetric potentials provided by the Néel walls. The combination of these elements leads to a superconducting ratchet effect. Thus, superconducting vortices driven by alternating forces and moving on magnetic half vortices generate a unidirectional net vortex flow. This ratchet effect is independent of the distribution of magnetic charges in the array.

Neuronal differentiation and cell-cycle programs mediate response to BET-bromodomain inhibition in MYC-driven medulloblastoma

BET-bromodomain inhibition (BETi) has shown pre-clinical promise for MYC-amplified medulloblastoma. However, the mechanisms for its action, and ultimately for resistance, have not been fully defined. Here, using a combination of expression profiling, genome-scale CRISPR/Cas9-mediated loss of function and ORF/cDNA driven rescue screens, and cell-based models of spontaneous resistance, we identify bHLH/homeobox transcription factors and cell-cycle regulators as key genes mediating BETi's response and resistance. Cells that acquire drug tolerance exhibit a more neuronally differentiated cell-state and expression of lineage-specific bHLH/homeobox transcription factors. However, they do not terminally differentiate, maintain expression of CCND2, and continue to cycle through S-phase. Moreover, CDK4/CDK6 inhibition delays acquisition of resistance. Therefore, our data provide insights about the mechanisms underlying BETi effects and the appearance of resistance and support the therapeutic use of combined cell-cycle inhibitors with BETi in MYC-amplified medulloblastoma.

Utility of 18F-fluoroestradiol (18F-FES) PET/CT imaging as a pharmacodynamic marker in patients with refractory estrogen receptor-positive solid tumors receiving Z-endoxifen therapy

BACKGROUND

Z-endoxifen is the most potent of the metabolites of tamoxifen, and has the potential to be more effective than tamoxifen because it bypasses potential drug resistance mechanisms attributable to patient variability in the expression of the hepatic microsomal enzyme CYP2D6. ¹⁸F-FES is a positron emission tomography (PET) imaging agent which selectively binds to estrogen receptor alpha (ER-α) and has been used for non-invasive in vivo assessment of ER activity in tumors. This study utilizes ¹⁸F-FES PET imaging as a pharmacodynamic biomarker in patients with ER+ tumors treated with Z-endoxifen.

METHODS

Fifteen patients were recruited from a parent therapeutic trial of Z-endoxifen and underwent imaging with ¹⁸F-FES PET at baseline. Eight had positive lesions on the baseline scan and underwent follow-up imaging with ¹⁸F-FES 1-5 days post administration of Z-endoxifen.

RESULTS

Statistically significant changes (p = 0.0078) in standard uptake value (SUV)-Max were observed between the baseline and follow-up scans as early as 1 day post drug administration.

CONCLUSION

F-FES PET imaging could serve as a pharmacodynamic biomarker for patients treated with ER-directed therapy.

Superconducting/magnetic Three-state Nanodevice for Memory and Reading Applications

We present a simple nanodevice that can operate in two modes: i) non-volatile three-state memory and ii) reading device. The nanodevice can retain three well defined states −1, 0 and +1 and can operate in a second mode as a sensor for external magnetic fields. The nanodevice is fabricated with an array of ordered triangular-shaped nanomagnets embedded in a superconducting thin film gown on Si substrates. The device runs based on the combination of superconducting vortex ratchet effect (superconducting film) with the out of plane magnetization (nanomagnets). The input signals are ac currents and the output signal are dc voltages. The memory mode is realized without applying a magnetic field and the nanomagnet stray magnetic fields govern the effect. In the sensor mode an external magnetic field is applied. The main characteristic of this mode is that the output signal is null for a precise value of the external magnetic field that only depends on the fabrication characteristics of the nanodevice.

Rocking ratchets in nanostructured superconducting-magnetic hybrids

Two rectification mechanisms in vortex lattice dynamics in Nb films have been studied. These two effects are based on ratchet effects, that is, an ac driving force induces a net dc vortex flow. In our case, an input ac current applied to the Nb films, grown on top of arrays of Ni nanotriangles, yields an output dc voltage. These two rectification effects occur when the vortex lattice moves in periodic asymmetric potentials. These pinning potentials are induced by the array of Ni triangles. In one configuration (longitudinal effect) the driven force is applied perpendicular to the triangle reflection symmetry axis; in the second one (transverse effect) the input current is injected parallel to the triangle reflection symmetry axis. In the framework of the rocking ratchet mechanism, the appropriate Langevin equation allows us to model the experimental data, taking into account the vortex-vortex interaction.

A superconducting reversible rectifier that controls the motion of magnetic flux quanta

We fabricated a device that controls the motion of flux quanta in a niobium superconducting film grown on an array of nanoscale triangular pinning potentials. The controllable rectification of the vortex motion is due to the asymmetry of the fabricated magnetic pinning centers. The reversal in the direction of the vortex flow is explained by the interaction between the vortices trapped on the magnetic nanostructures and the interstitial vortices. The applied magnetic field and input current strength can tune both the polarity and magnitude of the rectified vortex flow. Our ratchet system is explained and modeled theoretically, taking the interactions between particles into consideration.

Review of ocular ultrasonography

In this paper, the basics, screening technique and major indications of ocular ultrasound are described. This diagnostic technique proved to be an essential tool to examine intraocular structures when opacified ocular media inhibit direct examination and to evaluate retrobulbar structures when exophthalmos is evident.

Head and trunk in zebrafish arise via coinhibition of BMP signaling by bozozok and chordino

Spatial variations in the levels of bone morphogenetic protein (BMP) signaling are a critical determinant of dorsoanterior-ventroposterior pattern in vertebrate embryos. Whereas BMP overexpression abolishes both head and trunk development, known single and double loss-of-function mutations in BMP inhibitors have less dramatic effects. We report that combining mutations in the zebrafish genes bozozok and chordino causes a synergistic loss of head and trunk, whereas most cells express ventro-posterior markers and develop into a tail. Genetic inactivation of BMP signaling fully suppresses these defects. Thus, a remarkably simple genetic mechanism, involving a coinhibition of BMP function by the partially overlapping bozozok and chordino pathways is used to specify vertebrate head and trunk.

Maternal and zygotic activity of the zebrafish ogon locus antagonizes BMP signaling

The dorsal-ventral axis of vertebrate embryos is thought to be specified by a gradient of bone morphogenetic protein (BMP) activity, which, in part, arises through the interaction of dorsally expressed antagonists Chordin and Noggin with the ventralizing BMPs. The zebrafish mercedes(tm305), ogon(m60), and short tail(b180) mutations produce ventralized phenotypes, including expanded bmp2b/4 expression domains. We find that the three mutations are allelic and that the locus they define, renamed ogon (ogo), maps to linkage group 25. The ogo(m60) and ogo(b180) mutations are deficiencies and thus represent null alleles, whereas the ENU-induced allele ogo(tm305) retains partial function. Aspects of the ogo(m60) and ogo(tm305) mutant phenotypes are fully suppressed by overexpression of BMP antagonists. Moreover, swirl(tc300), a null mutation in bmp2b, is epistatic to ogo(m60) mutation, providing further evidence that ogo normally functions in a BMP-dependent manner. Embryonic patterning is highly sensitive to maternal and zygotic ogo gene dosage, especially when the level of zygotic chordin activity is also reduced. However, elimination of the zygotic activity of both genes does not result in a completely ventralized embryo. Thus, while ogo and chordin are required to limit activity of BMPs, additional mechanisms must exist to block these ventralizing signals. We have ruled out zebrafish noggin homologues as candidates for the ogo gene, including a newly identified gene, nog1, which is specifically expressed in the gastrula organizer. The results suggest that ogo encodes an as yet unidentified dorsalizing factor that mediates dorsoventral patterning by directly or indirectly antagonizing BMP activity.

Hepatitis B vaccination results in 140 liver transplant recipients

BACKGROUND/AIMS

Human autologous liver transplantation is possible due to an adequate suppression of the body's immune response. This also causes a higher hepatitis infection rate, making hepatitis prevention very important.

MATERIALS AND METHODS

We describe our experience with hepatitis B virus vaccination in 140 adult liver transplant recipients, transplanted from 1986 to 1994 with more than one year of follow-up. Excluded were those who had hepatitis B surface antigens or antibodies to those antigens before the transplant. The vaccination schedule was 0-1-2 months with a double dose of recombinant vaccine.

RESULTS

The total response rate (surface antigen antibodies > 10 U) was 40% (56/140); the rate was 47.7% in men and 26% in women. At the end of the study, only 17.1% (24/140) of the patients had antibodies > 10 U. The response rate was higher in patients with antibodies to hepatitis B core antigen (66.6%) than in those lacking antibodies (31.7%), and more long lasting (42.4% vs 11.2%). The response rate in 116 patients with booster doses was 12.9%. Six correctly vaccinated patients (4.28%) acquired new hepatitis B virus infections after the operation.

CONCLUSIONS

The total response rate in these patients is much lower than in the general population, and there is a rapid decline of titers, probably due to immunosuppression. The role of booster doses in these patients should be clarified.

Experimental corneal neovascularisation using sucralfate and basic fibroblast growth factor

PURPOSE

To develop a non-inflammatory model of both acute and chronic angiogenesis in the rabbit cornea using a known directly angiogenic cytokine.

METHODS

Pellets made of the slow-release polymer Hydron (polyhydroxyethylmethacrylate) and containing sucralfate and/or basic fibroblast growth factor (basic-FGF) were implanted into rabbit corneas. The neovascular response to the implantation of pellets containing basic-FGF alone, sucralfate alone or a titration of basic-FGF in the presence of a constant amount of sucralfate was measured. The role of inflammation in the neovascular response was also investigated.

RESULTS

The addition of sucralfate to the pellets led to the sustained release of basic-FGF resulting in a predictable and aggressive neovascular response with a low dose of basic-FGF that by itself was unable to elicit neovascularisation. At a dose of 500 ng per pellet, approximately one-third of the surface area of the cornea was vascularised within eight days of implantation. Minimal or no vascularisation occurred with the same dose of basic-FGF without sucralfate. While this dose of basic-FGF induced corneal oedema, only minimal inflammation was observed and the response was unaffected by ionising radiation. A less aggressive though still robust neovascular response with no or only minimal oedema was observed when the dose was lowered to 50 ng of basic-FGF per pellet. Some induced vessels persisted for more than three months.

CONCLUSION

This is an inexpensive in vivo model of angiogenesis with the advantages of the neovascularisation being aggressive, predictable, persistent, unassociated with an obvious inflammatory response and induced by the sustained release of an agent known to have a direct stimulatory action on endothelial cells.

Angiostatic steroids potentiated by sulfated cyclodextrins inhibit corneal neovascularization

It is known that hydrocortisone can be converted to a potent angiogenesis inhibitor by coadministration with heparin or with a sulfated cyclodextrin. The activity of tetrahydrocortisol-S, a purely angiostatic corticosteroid, can be potentiated by beta-cyclodextrin tetradecasulfate as shown in this study. This drug "pair" and other pairs of corticosteroids and beta-cyclodextrin tetradecasulfate can be applied topically to inhibit corneal neovascularization. Endotoxin-induced corneal neovascularization in rabbits was treated with beta-cyclodextrin tetradecasulfate coadministered with either: hydrocortisone, tetrahydrocortisol-S, or 6-alpha-fluoro-17,21-dihydroxy-16-beta-methyl-pregna-4,9(11),diene,3, 20-dione. When optimal ratios of steroid and cyclodextrin were used, neovascularization was reduced to 13%, 26%, and 28% of untreated controls for the three steroids, respectively. Hydrocortisone-cyclodextrin drug pairs suppressed virtually all inflammatory cell infiltration (induced by endotoxin), whereas tetrahydrocortisol-cyclodextrin pairs only partially reduced inflammation. These results demonstrate that corneal neovascularization and corneal inflammation are separable processes and that the neovascularization may be treated specifically using angiostatic steroids without inflammatory activity.

Successful treatment with ketoconazole of Cushing's syndrome in pregnancy

Patients with Cushing's syndrome rarely become pregnant. This is a high risk situation both for the fetus and the mother, if untreated. We report a patient with Cushing's syndrome due to adrenocortical adenoma who became pregnant and was successfully treated with ketoconazole during the last period of pregnancy.

Treatment of splenic artery aneurysm after distal splenorenal shunt. A case report

A patient with splenic artery aneurysm which developed after creation of selective distal spleno-renal shunt for hepatic cirrhosis and portal hypertension was presented. Three months after operation, an aneurysm of the splenic artery with a diameter of about 20 mm was detected. This aneurysm reached 4 cm three months later, and a resection was carried out. An arterial continuity was established by means of end-to-end anastomosis of the sectioned arterial ends. Because the flow through the splenic artery was about 60% of the total flow of the selective distal spleno-renal shunt, it is important to maintain continuity in order to avoid thrombosis of the shunt.

Extented esophago-gastretomy as surgical treatment for carcinoma of the cardia

With the object of designing a feasible and more radical surgical intervention for the treatment of carcinoma of the gastric cardia and improving the long term survival of these patients, a procedure was described which entails total esophagogastrectomy and resection of the distal pancreas, spleen and regional lymphnodes. The esophagus was mobilized via the diaphragmatic hiatus without thoracotomy. Intestinal continuity, installed isoperistaltically was restituted in the same operation using a segment of transverse and descending colon transferred to the left lateral cervical aspect by way of the posterior mediastinum. The procedure was used in four patients and mortality and serious complications were nil.

Selective coronary-caval shunt using internal jugular autograft, in the treatment of portal hypertension

The selective coronary-caval shunt is considered to be one of the better procedures in the surgical treatment of portal hypertension. We have altered the previously described technique by using an internal jugular vein grafting which possesses some advantages. We have performed this shunt utilizing an internal jugular vein autograft in eight patients, who had at least one major hemorrhage from esophageal varices three to twelve months before operation. There were no postoperative deaths. All four patients are still alive three months to six years after shunting without bleeding episodes. In the X-ray and endoscopic studies the esophagogastric varices were noted to be markedly smaller in size than they were before shunting.

Polarographic analysis of cephalexin

Cephalexin was found to be polarographically reducible after hydrolysis in an acidic medium, producing two polarographic waves. Both waves were diffusion controlled. The concentration-diffusion plot method was used for the analysis of cephalexin in capsules.

Interposition left gastric-caval shunt using internal jugular vein autograft in the treatment of portal hypertension

The selective left gastric-caval shunt is, in theory, one of the better procedures in the surgical treatment of portal hypertension. We have performed a modification of the previously described technique utilizing an internal jugular vein autograft in 4 patients who had had more than one major haemorrhage from oesophageal varices 3-12 months before operation. There were no post-operative deaths. All 4 patients are still alive 3 months to 4 years after shunting, with no episodes of bleeding. On radiological and endoscopic follow-up, the oesophagogastric varices were noted to be markedly smaller in size than before shunting.

Modification of nucleic acid synthesis in regenerating liver by azathioprine

The effect of azathioprine at 40 mg. per kilogram per day (LD25 at four days) was studied in rats following excision of two thirds of the liver. 1. The restoration of liver mass after four days was unchanged. 2. The rate of DNA synthesis was inhibited by a factor of 100 on the first day. DNA concentration decreased 24 percent by two days and 38 percent by four days in comparison with nontreated rats. 3. The rate of RNA synthesis was at first depressed, then accelerated. RNA concentrations were normal at four days. 4. The ratio of RNA to DNA was increased 59 percent at four days. 5. Hepatic regeneration was chiefly by cellular hypertrophy rather than by hyperplasia.