Optimized protocols for RNA interference in Macrostomum lignano

Macrostomum lignano, a marine free-living flatworm, has emerged as a potent invertebrate model in developmental biology for studying stem cells, germline, and regeneration processes. In recent years, many tools have been developed to manipulate this worm and to facilitate genetic modification. RNA interference is currently the most accessible and direct technique to investigate gene functions. It is obtained by soaking worms in artificial seawater containing dsRNA targeting the gene of interest. Although easy to perform, the original protocol calls for daily exchange of dsRNA solutions, usually until phenotypes are observed, which is both time- and cost-consuming. In this work, we have evaluated alternative dsRNA delivery techniques, such as electroporation and osmotic shock, to facilitate the experiments with improved time and cost efficiency. During our investigation to optimize RNAi, we demonstrated that, in the absence of diatoms, regular single soaking in artificial seawater containing dsRNA directly produced in bacteria or synthesized in vitro is, in most cases, sufficient to induce a potent gene knockdown for several days with a single soaking step. Therefore, this new and highly simplified method allows a very significant reduction of dsRNA consumption and lab work. In addition, it enables performing experiments on a larger number of worms at minimal cost.

Genome assembly of the acoel flatworm Symsagittifera roscoffensis, a model for research on body plan evolution and photosymbiosis

Symsagittifera roscoffensis is a well-known member of the order Acoela that lives in symbiosis with the algae Tetraselmis convolutae during its adult stage. Its natural habitat is the eastern coast of the Atlantic, where at specific locations thousands of individuals can be found, mostly, lying in large pools on the surface of sand at low tide. As a member of the Acoela it has been thought as a proxy for ancestral bilaterian animals; however, its phylogenetic position remains still debated. In order to understand the basic structural characteristics of the acoel genome, we sequenced and assembled the genome of aposymbiotic species S. roscoffensis. The size of this genome was measured to be in the range of 910-940 Mb. Sequencing of the genome was performed using PacBio Hi-Fi technology. Hi-C and RNA-seq data were also generated to scaffold and annotate it. The resulting assembly is 1.1 Gb large (covering 118% of the estimated genome size) and highly continuous, with N50 scaffold size of 1.04 Mb. The repetitive fraction of the genome is 61%, of which 85% (half of the genome) are LTR retrotransposons. Genome-guided transcriptome assembly identified 34,493 genes, of which 29,351 are protein coding (BUSCO score 97.6%), and 30.2% of genes are spliced leader trans-spliced. The completeness of this genome suggests that it can be used extensively to characterize gene families and conduct accurate phylogenomic reconstructions.

Proof of principle for piggyBac-mediated transgenesis in the flatworm Macrostomum lignano

Regeneration-capable flatworms are informative research models to study the mechanisms of stem cell regulation, regeneration, and tissue patterning. The free-living flatworm Macrostomum lignano is currently the only flatworm where stable transgenesis is available, and as such it offers a powerful experimental platform to address questions that were previously difficult to answer. The published transgenesis approach relies on random integration of DNA constructs into the genome. Despite its efficiency, there is room and need for further improvement and diversification of transgenesis methods in M. lignano. Transposon-mediated transgenesis is an alternative approach, enabling easy mapping of the integration sites and the possibility of insertional mutagenesis studies. Here, we report for the first time that transposon-mediated transgenesis using piggyBac can be performed in M. lignano to create stable transgenic lines with single-copy transgene insertions.

Assessment of aortic regurgitation mechanism with cardiac magnetic resonance: an echocardiography comparative study

Funding Acknowledgements

Type of funding sources: None.

Background

Aortic regurgitation (AR) quantification still remains challenging and requires an integrated approach. AR mechanism is one key parameter to take into account to assess its severity and repairability, and thus help to guide surgical decision. Although Cardiac Magnetic Resonance (CMR) has a growing interest in AR quantification, its performance to identify aortic AR mechanism has never been studied.

Purpose

We intended to define CMR Performance in this setting, by using echocardiography as reference.

Methods

AR mechanism was systematically evaluated in sixty-seven patients (81% male, mean age 46 ± 20 years) with chronic AR using CMR, and compared to transthoracic (TTE) and transesophageal (TEE) echocardiography as gold standard. AR were categorized as follows: type 1, aortic dilatation; type 2, Cusp prolapse; type 3, restrictive cusp motion. Jet direction, number of cusps and calcification (1 = no calcification, 2 = spots, 3 = big calcification interfering with cusp motion and 4 = Extensive with restricted cusp motion) were also evaluated.

Results

At TTE/TEE, mechanisms of AR were type 1 in 56 (83.5%), type 2 in 33 (49.2%), type 3 in 24 (35%). Agreement between TTE/TEE and CMR was modest, with respectively 74.6% (k= 0.4), 79.1% (k = 0.58) and 74.6% (k = 0.44). Bicuspid aortic valve was found in 44 (65.7%) patients at TTE/TEE, agreement with CMR was excellent, 98.5% (k = 0.97).  Jet was directed to the mitral valve in 42 (62.7%), at the inter ventricular septum in 12 (17.9%), and central in 13 (19.4%). Agreement with CMR was correct, respectively 80% (k = 0,6), 88% (k = 0.62) and 83.5% (K= 0.52). Calcification extension was 1 in 26 (38.8%), 2 in 25 (37.3%), 3 in 11 (16.4%) and 4 in 5 (7.5%). Agreement with CMR was poor, 44.7% (K= 0.28).

Conclusion

Accuracy between CMR and TTE/TEE to evaluate chronic AR mechanism and repairability was modest, with lower performance to define calcification extension.

Abstract Figure. AR classification TTE/TEE vs CMR

Utility of 3-dimensional transoesophageal echocardiography for mitral annular sizing in transcatheter mitral valve replacement procedures: a cardiac computed tomography comparative study

Funding Acknowledgements

Type of funding sources: None.

Background.  3-dimensional transoesophageal echocardiography (3D-TEE) is frequently used as an initial screening tool in the evaluation of patients who are candidates to Transcatheter Mitral Valve Replacement (TMVR). However, little is known about the imaging correlation with the gold-standard computed tomography (CT) imaging. We aimed at testing the quantitative differences between these two modalities and finding the best 3D-TEE parameters for TMVR screening.

Methods. We included 57 patients referred to our Heart Valve Clinic for TMVR with prostheses specifically designed for the mitral valve. Mitral annulus (MA) analyses were performed using commercially available software in 3D-TEE and CT.

Results. 3D-TEE was feasible in 52 patients (91%). Although 3D-TEE measurements were slightly lower than in CT, both measurements of projected MA area and perimeter showed excellent correlation with small differences between the two modalities (r = 0.88 and r = 0.92 respectively, p < 0.0001). Correlations were significant but lower for MA diameters (r = 0.68 to 0.72, p < 0.0001) and mitro-aortic angle (r = 0.53, p = 0.0001). ROC curve analyses showed that 3D-TEE had a good ability to predict TMVR screening success defined by constructors based on CT measurements with a range of 12.9 to 15cm² for MA area (AUC = 0.88-0.91, p < 0.0001), 128 to 139mm for MA perimeter (AUC = 0.85-0.91, p < 0.0001), 35 to 39mm for anteroposterior diameter (AUC = 0.79-0.84 p < 0.0001) and 37 to 42mm for posteromedial-anterolateral diameter (AUC = 0.81-0.89, p < 0.0001) (Figure 1). Conclusion. 3D-TEE measurements of MA dimensions display strong correlation with CT measurements in patients undergoing TMVR screening process. 3D-TEE should be proposed as a reasonable alternative to CT in this vulnerable population.

Abstract Figure.

The free-living flatworm Macrostomum lignano

Macrostomum lignano is a free-living flatworm that is emerging as an attractive experimental animal for research on a broad range of biological questions. One feature setting it apart from other flatworms is the successful establishment of transgenesis methods, facilitated by a steady supply of eggs in the form of single-cell zygotes that can be readily manipulated. This, in combination with the transparency of the animal and its small size, creates practical advantages for imaging and fluorescence-activated cell sorting in studies related to stem cell biology and regeneration. M. lignano can regenerate most of its body parts, including the germline, thanks to the neoblasts, which represent the flatworm stem cell system. Interestingly, neoblasts seem to have a high capacity of cellular maintenance, as M. lignano can survive up to 210 Gy of γ-irradiation, and partially offset the negative consequence of ageing. As a non-self-fertilizing simultaneous hermaphrodite that reproduces in a sexual manner, M. lignano is also used to study sexual selection and other evolutionary aspects of sexual reproduction. Work over the past several years has led to the development of molecular resources and tools, including high-quality genome and transcriptome assemblies, transcriptional profiling of the germline and somatic neoblasts, gene knockdown, and in situ hybridization. The increasingly detailed characterization of this animal has also resulted in novel research questions, such as bio-adhesion based on its adhesion-release glands and genome evolution due to its recent whole-genome duplication.

The regenerative flatworm Macrostomum lignano, a model organism with high experimental potential

Understanding the process of regeneration has been one of the longstanding scientific aims, from a fundamental biological perspective, as well as within the applied context of regenerative medicine. Because regeneration competence varies greatly between organisms, it is essential to investigate different experimental animals. The free-living marine flatworm Macrostomum lignano is a rising model organism for this type of research, and its power stems from a unique set of biological properties combined with amenability to experimental manipulation. The biological properties of interest include production of single-cell fertilized eggs, a transparent body, small size, short generation time, ease of culture, the presence of a pluripotent stem cell population, and a large regeneration competence. These features sparked the development of molecular tools and resources for this animal, including high-quality genome and transcriptome assemblies, gene knockdown, in situ hybridization, and transgenesis. Importantly, M. lignano is currently the only flatworm species for which transgenesis methods are established. This review summarizes biological features of M. lignano and recent technological advances towards experimentation with this animal. In addition, we discuss the experimental potential of this model organism for different research questions related to regeneration and stem cell biology.

A carcinogenic trigger to study the function of tumor suppressor genes in Schmidtea mediterranea

Planarians have been long known for their regenerative ability, which hinges on pluripotency. Recently, however, the planarian model has been successfully established for routine toxicological screens aimed to assess overproliferation, mutagenicity and tumorigenesis. In this study, we focused on planarian tumor suppressor genes (TSGs) and their role during chemically induced carcinogenic stress in Schmidtea mediterranea Combining in silico and proteomic screens with exposure to human carcinogen type 1A agent cadmium (Cd), we showed that many TSGs have a function in stem cells and that, in general, exposure to Cd accelerated the onset and increased the severity of the observed phenotype. This suggested that the interaction between environmental and genetic factors plays an important role in tumor development in S. mediterranea Therefore, we further focused on the synergistic effects of Cd exposure and p53 knockdown (KD) at the cellular and molecular levels. Cd also produced a specific proteomic landscape in homeostatic animals, with 172 proteins differentially expressed, 43 of which were downregulated. Several of these proteins have tumor suppressor function in human and other animals, namely Wilms Tumor 1 Associated Protein (WT1), Heat Shock Protein 90 (HSP90), Glioma Pathogenesis-Related Protein 1 (GLIPR1) and Matrix Metalloproteinase B (Smed-MMPB). Both Glipr1 and MmpB KD produced large outgrowths, epidermal lesions and epidermal blisters. The epidermal blisters that formed as a consequence of Smed-MmpB KD were populated by smedwi1+ cells, many of which were actively proliferating, while large outgrowths contained ectopically differentiated structures, such as photoreceptors, nervous tissue and a small pharynx. In conclusion, Smed-MmpB is a planarian TSG that prevents stem cell proliferation and differentiation outside the proper milieu.

Resilience to aging in the regeneration-capable flatworm Macrostomum lignano

Animals show a large variability of lifespan, ranging from short-lived as Caenorhabditis elegans to immortal as Hydra. A fascinating case is flatworms, in which reversal of aging by regeneration is proposed, yet conclusive evidence for this rejuvenation-by-regeneration hypothesis is lacking. We tested this hypothesis by inducing regeneration in the sexual free-living flatworm Macrostomum lignano. We studied survival, fertility, morphology, and gene expression as a function of age. Here, we report that after regeneration, genes expressed in the germline are upregulated at all ages, but no signs of rejuvenation are observed. Instead, the animal appears to be substantially longer lived than previously appreciated, and genes expressed in stem cells are upregulated with age, while germline genes are downregulated. Remarkably, several genes with known beneficial effects on lifespan when overexpressed in mice and C. elegans are naturally upregulated with age in M. lignano, suggesting that molecular mechanism for offsetting negative consequences of aging has evolved in this animal. We therefore propose that M. lignano represents a novel powerful model for molecular studies of aging attenuation, and the identified aging gene expression patterns provide a valuable resource for further exploration of anti-aging strategies.

A novel flatworm-specific gene implicated in reproduction in Macrostomum lignano

Free-living flatworms, such as the planarian Schmidtea mediterranea, are extensively used as model organisms to study stem cells and regeneration. The majority of flatworm studies so far focused on broadly conserved genes. However, investigating what makes these animals different is equally informative for understanding its biology and might have biomedical value. We re-analyzed the neoblast and germline transcriptional signatures of the flatworm M. lignano using an improved transcriptome assembly and show that germline-enriched genes have a high fraction of flatworm-specific genes. We further identified the Mlig-sperm1 gene as a member of a novel gene family conserved only in free-living flatworms and essential for producing healthy spermatozoa. In addition, we established a whole-animal electron microscopy atlas (nanotomy) to visualize the ultrastructure of the testes in wild type worms, but also as a reference platform for different ultrastructural studies in M. lignano. This work demonstrates that investigation of flatworm-specific genes is crucial for understanding flatworm biology and establishes a basis for such future research in M. lignano.

Transcriptional signatures of somatic neoblasts and germline cells in Macrostomum lignano

The regeneration-capable flatworm Macrostomum lignano is a powerful model organism to study the biology of stem cells in vivo. As a flatworm amenable to transgenesis, it complements the historically used planarian flatworm models, such as Schmidtea mediterranea. However, information on the transcriptome and markers of stem cells in M. lignano is limited. We generated a de novo transcriptome assembly and performed the first comprehensive characterization of gene expression in the proliferating cells of M. lignano, represented by somatic stem cells, called neoblasts, and germline cells. Knockdown of a selected set of neoblast genes, including Mlig-ddx39, Mlig-rrm1, Mlig-rpa3, Mlig-cdk1, and Mlig-h2a, confirmed their crucial role for the functionality of somatic neoblasts during homeostasis and regeneration. The generated M. lignano transcriptome assembly and gene expression signatures of somatic neoblasts and germline cells will be a valuable resource for future molecular studies in M. lignano.

DOI:http://dx.doi.org/10.7554/eLife.20607.001

Guanine quadruplex structures localize to heterochromatin

Increasing amounts of data support a role for guanine quadruplex (G4) DNA and RNA structures in various cellular processes. We stained different organisms with monoclonal antibody 1H6 specific for G4 DNA. Strikingly, immuno-electron microscopy showed exquisite specificity for heterochromatin. Polytene chromosomes from Drosophila salivary glands showed bands that co-localized with heterochromatin proteins HP1 and the SNF2 domain-containing protein SUUR. Staining was retained in SUUR knock-out mutants but lost upon overexpression of SUUR. Somatic cells in Macrostomum lignano were strongly labeled, but pluripotent stem cells labeled weakly. Similarly, germline stem cells in Drosophila ovaries were weakly labeled compared to most other cells. The unexpected presence of G4 structures in heterochromatin and the difference in G4 staining between somatic cells and stem cells with germline DNA in ciliates, flatworms, flies and mammals point to a conserved role for G4 structures in nuclear organization and cellular differentiation.

Stem cells propagate their DNA by random segregation in the flatworm Macrostomum lignano

Adult stem cells are proposed to have acquired special features to prevent an accumulation of DNA-replication errors. Two such mechanisms, frequently suggested to serve this goal are cellular quiescence, and non-random segregation of DNA strands during stem cell division, a theory designated as the immortal strand hypothesis. To date, it has been difficult to test the in vivo relevance of both mechanisms in stem cell systems. It has been shown that in the flatworm Macrostomum lignano pluripotent stem cells (neoblasts) are present in adult animals. We sought to address by which means M. lignano neoblasts protect themselves against the accumulation of genomic errors, by studying the exact mode of DNA-segregation during their division. In this study, we demonstrated four lines of in vivo evidence in favor of cellular quiescence. Firstly, performing BrdU pulse-chase experiments, we localized 'Label-Retaining Cells' (LRCs). Secondly, EDU pulse-chase combined with Vasa labeling demonstrated the presence of neoblasts among the LRCs, while the majority of LRCs were differentiated cells. We showed that stem cells lose their label at a slow rate, indicating cellular quiescence. Thirdly, CldU/IdU- double labeling studies confirmed that label-retaining stem cells showed low proliferative activity. Finally, the use of the actin inhibitor, cytochalasin D, unequivocally demonstrated random segregation of DNA-strands in LRCs. Altogether, our data unambiguously demonstrated that the majority of neoblasts in M. lignano distribute their DNA randomly during cell division, and that label-retention is a direct result of cellular quiescence, rather than a sign of co-segregation of labeled strands.

Single-centre prospective comparison between contrast-enhanced ultrasound and computed tomography angiography after EVAR

AIM

To evaluate contrast-enhanced ultrasound (CEUS) as an effective alternative to CT-angiography (CTA) for endoleak detection and aneurismal sac diameter measurement in the follow-up after endovascular abdominal aortic aneurysm repair (EVAR).

METHODS

From January 2006 to December 2010, 395 patients underwent EVAR follow-up with both CTA and CEUS. The diameter of the aneurismal sac and the presence of endoleaks were evaluated in all the 395 paired examinations.

RESULTS

Bland-Altman plots showed a good agreement in aneurismal sac diameter evaluation between the two imaging modalities. The mean diameter was 54.93 mm (standard deviation (SD) ±12.57) with CEUS and 56.01 mm (SD ± 13.23) with CTA. The mean difference in aneurismal sac diameter was -1.08 mm ± 3.3543 (95% confidence interval (CI), -0.75 to -1.41), in favour of CTA. The number of observed agreement in endoleak detection was 359/395 (90.89%). The two modalities detected the same type I and type III endoleaks. McNemar's χ(2) test confirmed that CTA and CEUS are equivalent in endoleak detection.

CONCLUSIONS

CEUS demonstrated to be as accurate as CTA in endoleak detection and abdominal aortic aneurysm diameter measurements during EVAR follow-up, without carrying the risks of radiation exposure or nephrotoxicity. Even if it cannot be proposed as the sole imaging modality during follow-up, our analysis suggests that it should have a major role.

Lack of metabolic ageing in the long-lived flatworm Schmidtea polychroa

Freshwater planarians have a large totipotent stem cell population allowing high rates of cell renewal and morphological plasticity. It is often suggested that they are able to rejuvenate during fission, regeneration and starvation. These features, together with the rapidly expanding molecular toolset, make planarians such as Schmidtea polychroa and S. mediterranea interesting for ageing research. Yet, the basic demographic and physiological data are lacking or still based on fragmentary observations of one century ago. Here, we present the first longitudinal physiological study of the species S. polychroa. Survival, size and metabolic rate, measured by microcalorimetry, of a cohort of 28 individuals were followed over a period of three years. Sexual maturity was reached during the second month after which the worms continued growing up to 5 months. This initial growth phase was followed by alternating periods of synchronised growth and degrowth. Although mass-specific metabolic rates declined during the initial growth phase, no changes were found later in life. The absence of metabolic ageing may be explained by the very high rate of cell renewal during homeostasis and alternating phases of degrowth and growth during which tissues are renewed. Surprisingly, all deaths occurred in pairs of worms that were housed in the same culture recipient, suggesting that worms did not die from ageing. Taking into account the metabolic and demographic data, we suggest that S. polychroa shows negligible ageing. Detailed analyses of size and metabolic rate revealed a remarkable biphasic allometric scaling relation. During the initial growth phase (months 1-5) the allometric scaling exponent b was 0.86 while later in life, it increased to an unusually large value of 1.17, indicating that mass-specific metabolic rate increases with size in adult S. polychroa.

[Idiopathic vasospastic angiopathy of the internal carotid arteries: A rarely recognized cause of ischemic stroke in young individuals]

INTRODUCTION

Idiopathic vasospastic angiopathy of the internal carotid arteries is a rare and largely unknown cause of ischemic stroke.

METHODS

We report the case of a 39-year-old man with migraine treated by beta-blockers, who had been suffering from progressive right visual impairment and headache for one week. He then experienced a seizure and left hemiparesis. Ophthalmological examination revealed right retinal ischemia and partial left homonymous hemianopia. MRI revealed a long stenosis of both carotid arteries and a recent ischemic stroke in the territory of the right middle cerebral artery. The diagnosis of vasospastic angiopathy of the internal carotid arteries was made based on a second MRI and colored duplex sonography which showed a decrease in the stenosis and no intraparietal hematoma confirming the vasospasm mechanism for stenosis. The clinical course was favorable with calcium channel blockers and aspirin. Use of vasoconstrictor treatments was contraindicated.

DISCUSSION/CONCLUSION

Idiopathic vasospastic angiopathy of the internal carotid arteries has been rarely documented. Association with migraine has been mentioned but remains unclear in the literature. This etiology for stroke is probably under-diagnosed due to lack of rapid and repeated examinations of the cervical arteries (angio-MR and colored duplex sonography) to confirm the vasospasm mechanism. Recurrences have been reported justifying a specific secondary preventive treatment to induce vasodilatation. Vasoconstrictor treatments should be contraindicated.

Embryonic origins of hull cells in the flatworm Macrostomum lignano through cell lineage analysis: developmental and phylogenetic implications

The development of macrostomid flatworms is of interest for evolutionary developmental biology research because these taxa combine characteristics of the canonical spiral cleavage pattern with significant deviations from this pattern. One such deviation is the formation of hull cells, which surround the remaining embryonic primordium during early development. Using live observations with a 4D microscope system, histology, and 3D reconstructions, we analyzed the ontogeny of these hull cells in the macrostomid model organism Macrostomum lignano. Our cell lineage analysis allowed us to find the precursors of the hull cells in this species. We discuss the relation between macrostomid development and the development of other spiralians and the question of whether hull cells are homologous within rhabditophoran flatworms.

Demographic analysis reveals gradual senescence in the flatworm Macrostomum lignano

Free-living flatworms ("Turbellaria") are appropriate model organisms to gain better insight into the role of stem cells in ageing and rejuvenation. Ageing research in flatworms is, however, still scarce. This is partly due to culture difficulties and the lack of a complete set of demographic data, including parameters such as median lifespan and age-specific mortality rate. In this paper, we report on the first flatworm survival analysis. We used the species Macrostomum lignano, which is an emerging model for studying the reciprocal influence between stem cells, ageing and rejuvenation. This species has a median lifespan of 205 +/- 13 days (average +/- standard deviation [SD]) and a 90th percentile lifespan of 373 +/- 32 days. The maximum lifespan, however, is more than 745 days, and the average survival curve is characterised by a long tail because a small number of individuals lives twice as long as 90% of the population. Similar to earlier observations in a wide range of animals, in M. lignano the age-specific mortality rate increases exponentially, but levels off at the oldest ages. To compare the senescence of M. lignano with that of other ageing models, we determined the mortality rate doubling time, which is 0.20 +/- 0.02 years. As a result, we can conclude that M. lignano shows gradual senescence at a rate similar to the vertebrate ageing models Rattus norvegicus and Mus musculus. We argue that M. lignano is a suitable model for ageing and rejuvenation research, and especially for the role of stem cells in these processes, due to its accessible stem cell system and regeneration capacity, and the possibility of combining stem cell studies with demographic analyses.

Ontogeny of the complex sperm in the macrostomid flatworm Macrostomum lignano (Macrostomorpha, Rhabditophora)

Spermiogenesis in Macrostomum lignano (Macrostomorpha, Rhabditophora) is described using light- and electron microscopy of the successive stages in sperm development. Ovoid spermatids develop to highly complex, elongated sperm possessing an undulating distal (anterior) process (or "feeler"), bristles, and a proximal (posterior) brush. In particular, we present a detailed account of the morphology and ontogeny of the bristles, describing for the first time the formation of a highly specialized bristle complex consisting of several parts. This complex is ultimately reduced when sperm are mature. The implications of the development of this bristle complex on both sperm maturation and the evolution and function of the bristles are discussed. The assumed homology between bristles and flagellae questioned.

Méningiome du nerf optique. L’expérience lyonnaise

Meningioma is an unfrequent optic nerve tumor. Clinical symptoms are not specific, and pathology exam not easily accessible. The diagnosis is usually based on imaging findings. We report our experience, based on twenty patients. Most of them were middle-aged women (mean age=47 years old). The optic nerve meningioma (ONM) was often revealed by visual dysfunction. Ophthalmological evaluation was altered in most patients (visual acuity, visual fields, fundi). The gold-standard exam was MRI of the optic nerve, with and without gadolinium, and with fat-sat sequences. Thirty percent of the lesions remain stable without treatment. Functional prognosis has been improved only by conformal fractionated radiotherapy, but indications and modalities remain to be specified.

Hyperthyroidism and Cerebral Venous Thrombosis

The demonstration of an underlying prothrombotic condition in cerebral venous thrombosis (CVT) may have important practical consequences in terms of prevention. Thyrotoxicosis through a hypercoagulable state may be a predisposing factor for CVT. The authors present the cases of 4 patients who developed CVT and hyperthyroidism. At the acute stage, hyperthyroidism was associated with an increase in factor VIII (FVIII). At follow-up, FVIII level remained increased in 2 patients. Hyperthyroidism may have an impact on FVIII level. Accordingly in patients with hyperthyroidism and neurological symptoms, the diagnosis of CVT should be considered and an exhaustive coagulation screening may be appropriate.

Tobacco smoking by pregnant women. Disturbances in metabolism of branched chain amino acids and fetal growth

Pregnancy alone lowered the plasma AA concentrations of ileu, leu, and val when compared to their concentrations in nonpregnant nonsmokers. Plasma concentrations of val, ileu, and leu were significantly higher in pregnant smokers than in pregnant nonsmokers. Therefore, the utilization of BCAA was more reduced in pregnant smokers than that which could be predicted from plasma AA concentrations of nonpregnant nonsmokers.

African Burkitt's lymphoma in the Cape province of South Africa and in Namibia

The clinical features, incidence and pattern of jaw involvement, and seasonal occurrence in relation to 22 patients with Burkitt's lymphoma in the Cape province and Southwest Africa were analyzed. The mean age, male dominance, and pattern of organ involvement paralleled typical African Burkitt's lymphoma. Development of the patients' disease was more likely during the rainy season. The frequency and pattern of jaw involvement resembled typical African Burkitt's lymphoma. The frequency of jaw involvement was similar in white and nonwhite patients. Members of all racial groups had typical African Burkitt's lymphoma.

Effect of preeclampsia on carboxyhemoglobin levels: a mechanism for a decrease in P50

COHb levels were measured in 15 preeclamptic pregnant women and 15 normal pregnant women to investigate the cause for the decrease in P50 associated with preeclampsia. The authors also included six normal and six preeclamptic pregnant patients from the above groups in the determination of P50. Measurements of COHb levels were performed in a Radiometer OSM2 Hemoximeter. Determination of P50 was done using an IL 237 Tonometer, a Radiometer, OSM2 Hemoximeter, and a Corning 168 pH/Blood Gas Analyzer. Preeclamptic pregnant patients had a mean COHb level of 2.8%, whereas normal pregnant women had a mean COHb level of 0.7% (P less than 0.001). Preeclamptic patients also had a significantly lower (24.4 mmHg) P50 than normal pregnant women (P50 = 30.1 mmHg) (P less than 0.001). The authors conclude that a significant elevation of COHb in preeclamptic pregnant women is partly responsible for a significant decrease in P50 seen in preeclampsia.

Effect of pre-eclampsia on plasma cholinesterase activity

Plasma cholinesterase (PCHE) activity was determined using a colorimetric method in 11 healthy non-pregnant women, 11 healthy pregnant women at term, and 11 pre-eclamptic pregnant women at term. The mean plasma cholinesterase activities for healthy non-pregnant women, healthy pregnant women and pre-eclamptic pregnant women were 438 +/- 81,257 +/- 25 and 173 +/- 18 units . ml-1, respectively. Our data suggest that there is a significant reduction in plasma cholinesterase activity in preeclamptic pregnant women when compared to healthy non-pregnant (p less than 0.001) and healthy pregnant women (p less than 0.001).

Type I histiocytosis X presenting as biliary atresia. A case report

Histiocytosis X may present in a variety of ways. We report a patient who presented with the unusual feature of infiltration of the hepatic duct with histiocytes, manifesting as biliary atresia.