Ecological implications of pedogenesis and geochemistry of ultramafic soils in Kinabalu Park (Malaysia)

In Sabah, Malaysia, ultramafic rock outcrops are widespread (totalling 3500 km2, one of the main outcrops in the tropical zone), and predominantly of the peridotite type. However, strongly serpentinised peridotite is also locally common, particularly along fault lines in the Mt. Kinabalu area. This study aimed to determine the extent of chemical variation in ultramafic soils in relation to the degree of serpentinisation and the weathering intensity, and consequent potential ecological implications linked to resulting soil chemical fertility. It was hypothesized that young soils and soils derived from bedrock with a significant degree of serpentinisation strongly differ from typical Geric Ferralsols and result in soil chemistries with more adverse properties to plant life (e.g. low availability of the essential nutrients N, P, K and Ca and high concentrations of potentially phytotoxic Mg and Ni). Ultramafic soil diversity linked to the age of the soil or the degree of serpentinisation would thus be a main factor of plant diversity and distribution. The diverse topography of Kinabalu Park (ultramafic soils present between 400 and 2950 m asl) has given rise to high pedodiversity with the broad overall ultramafic soil types being: (i) deep laterite soils (Geric Ferralsols); (ii) moderately deep montane soils (Dystric Cambisols) with mor humus; (iii) shallow skeletal soils at high altitude (Eutric Cambisols Hypermagnesic); and (iv) bare serpentinite soils (Hypereutric Leptosols Hypermagnesic) at low altitude (200–700 m asl). Leptosols on serpentinite and Eutric Cambisols have the most extreme chemical properties in the whole Kinabalu Park area both with very high Mg:Ca molar quotients, with either high available Ni (Cambisols) or high pH (Leptosols). These soils host specific and adapted vegetation (high level of endemism) that tolerates geochemical peculiarities, including Ni hyperaccumulators. Geric Ferralsols present far less chemical constraints than Hypermagnesian Cambisols soils to the vegetation and host a tall and very diverse rainforest, not so different than that on non-ultramafic soils. It therefore appears that altitude, soil age and degree of bedrock serpentinisation are the main determining factors of soil properties: the qualifier “ultramafic” alone is not sufficient to define soil geochemical and ecological conditions in the Kinabalu Park area, probably more than in any other ultramafic region in the world

Mitchell-Riley Syndrome : Improving Clinical Outcomes and Searching for Functional Impact of RFX-6 Mutations

Aims/HypothesisCaused by biallelic mutations of the gene encoding the transcription factor RFX6, the rare Mitchell-Riley syndrome (MRS) comprises neonatal diabetes, pancreatic hypoplasia, gallbladder agenesis or hypoplasia, duodenal atresia, and severe chronic diarrhea. So far, sixteen cases have been reported, all with a poor prognosis. This study discusses the multidisciplinary intensive clinical management of 4 new cases of MRS that survived over the first 2 years of life. Moreover, it demonstrates how the mutations impair the RFX6 function. MethodsClinical records were analyzed and described in detail. The functional impact of two RFX6(R181W) and RFX6(V506G) variants was assessed by measuring their ability to transactivate insulin transcription and genes that encode the L-type calcium channels required for normal pancreatic beta-cell function. ResultsAll four patients were small for gestational age (SGA) and prenatally diagnosed with duodenal atresia. They presented with neonatal diabetes early in life and were treated with intravenous insulin therapy before switching to subcutaneous insulin pump therapy. All patients faced recurrent hypoglycemic episodes, exacerbated when parenteral nutrition (PN) was disconnected. A sensor-augmented insulin pump therapy with a predictive low-glucose suspension system was installed with good results. One patient had a homozygous c.1517T>G (p.Val506Gly) mutation, two patients had a homozygous p.Arg181Trp mutation, and one patient presented with new compound heterozygosity. The RFX6(V506G) and RFX6(R181W) mutations failed to transactivate the expression of insulin and genes that encode L-type calcium channel subunits required for normal pancreatic beta-cell function. Conclusions/InterpretationMultidisciplinary and intensive disease management improved the clinical outcomes in four patients with MRS, including adjustment of parenteral/oral nutrition progression and advanced diabetes technologies. A better understanding of RFX6 function, in both intestine and pancreas cells, may break ground in new therapies, particularly regarding the use of drugs that modulate the enteroendocrine system.Peer reviewe

A step toward liver gene therapy: efficient correction of the genetic defect of hepatocytes isolated from a patient with Crigler-Najjar syndrome type 1 with lentiviral vectors

BACKGROUND: Ex vivo liver gene therapy may be a future alternative to orthotopic liver transplantation for the treatment of some liver diseases. We previously described the transduction in suspension with lentiviral vectors and immediate hepatocyte transplantation (SLIT) protocol and its high transduction rate with normal human hepatocytes. We also reported SLIT efficiency in the animal model of Crigler-Najjar type 1 syndrome (CN-1), the Gunn rat. Here, we evaluated SLIT efficiency with diseased human hepatocytes. METHODS: Hepatocytes of the liver from a 4-year-old patient presenting CN-1 were isolated. They were transduced with liver-specific lentiviral vectors expressing uridine-diphosphate-glucuronosyltransferase (hUGT1A1) or green fluorescent protein, and then analyzed in vitro for transduction efficiency and hUGT1A1 expression, or transplanted in nonobese diabetic/severe combined immunodeficiency (SCID) mice to evaluate long-term survival of transplanted cells. RESULTS: More than 90% of CN-1 hepatocytes were transduced. Hepatocytes produced hUGT1A1 protein after lentiviral transduction. After having been subjected to the SLIT, lentivirally transduced CN-1 hepatocytes engrafted long term (up to 26 weeks posttransplantation) in recipient livers and expressed green fluorescent protein or hUGT1A1 vector. CONCLUSION: The SLIT protocol allowed for a high transduction of CN-1 hepatocytes and restoration of the expression of the deficient protein. Furthermore, long-term survival of lentivirally transduced CN-1 hepatocytes in the liver of immunodeficient mice was demonstrated. This study is therefore an important step toward human application of lentiviral gene therapy

Impact of age at Kasai operation on its results in late childhood and adolescence: a rational basis for biliary atresia screening

BACKGROUND: Increased age at surgery has a negative impact on results of the Kasai operation for biliary atresia in infancy and early childhood. It remained unclear if an age threshold exists and if this effect persists with extended follow-up. In this study we examined the relationship between increased age at surgery and its results in adolescence. METHODS: All patients with biliary atresia who were living in France and born between 1986 and 2002 were included. Median follow-up in survivors was 7 years. RESULTS: Included in the study were 743 patients with biliary atresia, 695 of whom underwent a Kasai operation; 2-, 5-, 10-, and 15-year survival rates with native liver were 57.1%, 37.9%, 32.4%, and 28.5%, respectively. Median age at Kasai operation was 60 days and was stable over the study period. Whatever the follow-up (2, 5, 10, or 15 years), survival rates with native liver decreased when age at surgery increased ( ≤ 30, 31-45, 46-60, 61-75, and 76-90 days). Accordingly, we estimated that if every patient with biliary atresia underwent the Kasai operation before 46 days of age, 5.7% of all liver transplantations performed annually in France in patients younger than 16 years could be spared. CONCLUSIONS: Increased age at surgery had a progressive and sustained deleterious effect on the results of the Kasai operation until adolescence. These findings indicate a rational basis for biliary atresia screening to reduce the need for liver transplantations in infancy and childhood

Management of patients with biliary atresia in France: results of a decentralized policy 1986-2002

This study analyzed the results of the decentralized management of biliary atresia (BA) in France, where an improved collaboration between centers has been promoted since 1997. Results were compared to those obtained in England and Wales, where BA patients have been centralized in three designated centers since 1999. According to their birth dates, BA patients were divided into two cohorts: cohort A, with patients born between 1986 and 1996, had 472 patients; and cohort B, with patients born between 1997 and 2002, had 271 patients. Survival rates were calculated according to the Kaplan-Meier method and compared by using the log rank test and the Cox model. Four-year overall BA patient survival was 73.6% (95% CI 69.5%-77.7%) and 87.1% (CI 82.6%-91.6%) in cohorts A and B, respectively (P < .001). Median age at time of the Kasai operation was 61 and 57 days in cohorts A and B, respectively (NS). Four-year survival with native liver after the Kasai operation was 40.1% and 42.7% in cohorts A and B, respectively (NS): 33.9% (cohort A) and 33.4% (cohort B) in the centers with two or fewer caseloads a year, 30.9% (cohort A) and 44.5% (cohort B) in the centers with 3-5 cases/year, 47.8% (cohort A) and 47.7% (cohort B) in the center with more than 20 caseloads a year. In cohorts A and B, 74 (15.7%) and 19 (7%) patients, respectively, died without liver transplantation (LT). Four-year survival after LT was 75.1% and 88.8% in cohorts A and B, respectively (P = .006). In conclusion, BA patients currently have the same chance of survival in France as in England and Wales. The early success rate of the Kasai operation remains inferior in the centers with limited caseloads in France, leading to a greater need for LTs in infancy and early childhood

Ex vivo lentivirus transduction and immediate transplantation of uncultured hepatocytes for treating hyperbilirubinemic Gunn rat

BACKGROUND: Ex vivo liver gene therapy provides an attractive alternative to orthotopic liver transplantation for the treatment of liver diseases. We previously reported a protocol in which human primary hepatocytes are highly transduced in Suspension with Lentiviral vectors and Immediately Transplanted (SLIT). Here, we evaluated the SLIT approach in Gunn rats, the animal model for Crigler-Najjar syndrome type 1, a defect in bilirubin UDP-glucuronosyltransferase (BUGT). METHODS: We constructed lentiviral vectors coding for BUGT under control of an ubiquitous promoter. Control vectors contained Green Fluorescent Protein (GFP) under control of the same promoter. Hepatocytes were isolated from jaundiced Gunn rats and transduced in suspension for four hr. After washing, 2x10 hepatocytes were immediately transplanted into syngeneic rats. Bilirubinemia and bile pigments were regularly assessed after cell transplantation. The percentage and presence of transduced hepatocytes was analyzed by immunohistochemistry in GFP-transplanted animals. RESULTS: In rats receiving BUGT-transduced hepatocytes, bilirubinemia decreased by about 30%. The level of correction remained stable for up to 240 days. Bilirubin glucuronides were present in the bile of treated animals, indicating the metabolic activity of engrafted hepatocytes. In contrast, bilirubinemia in GFP-transplanted rats did not decline but rather increased. GFP-positive hepatocytes amounted to 0.5-1% of the liver, which is in agreement with the number of transplanted and genetically-modified hepatocytes (6x10). CONCLUSIONS: This work reports the first demonstration of long-term metabolic benefit after rapid transplantation of ex vivo lentivirally tranduced hepatocytes. Therefore, this study demonstrates the therapeutic proof-of-principle and potential of the SLIT approach for treating inherited metabolic liver diseases

Long-term outcome of children with patent processus vaginalis incidentally diagnosed by laparoscopy

Patent processus vaginalis (PPV) might be incidentally diagnosed during laparoscopy. The aims of this study were to determine the prevalence and the natural history of PPV, i.e. its possible development into symptomatic inguinal hernia

Lipids containing medium-chain fatty acids are specific to post-whole genome duplication Saccharomycotina yeasts

Background: Yeasts belonging to the subphylum Saccharomycotina have been used for centuries in food processing and, more recently, biotechnology. Over the past few decades, these yeasts have also been studied in the interest of their potential to produce oil to replace fossil resources. Developing yeasts for massive oil production requires increasing yield and modifying the profiles of the fatty acids contained in the oil to satisfy specific technical requirements. For example, derivatives of medium-chain fatty acids (MCFAs, containing 6-14 carbons) are used for the production of biodiesels, cleaning products, lubricants and cosmetics. Few studies are available in the literature on the production of MCFAs in yeasts. Results: We analyzed the MCFA content in Saccharomyces cerevisiae grown in various conditions. The results revealed that MCFAs preferentially accumulated when cells were grown on synthetic media with a high C/N ratio at low temperature (23 degrees C). Upon screening deletion mutant strains for genes encoding lipid droplet-associated proteins, we found two genes, LOA1 and TGL3, involved in MCFA homeostasis. A phylogenetic analysis on 16 Saccharomycotina species showed that fatty acid profiles differed drastically among yeasts. Interestingly, MCFAs are only present in post-whole genome duplication yeast species. Conclusions: In this study, we produced original data on fatty acid diversity in yeasts. We demonstrated that yeasts are amenable to genetic and metabolic engineering to increase their MCFA production. Furthermore, we revealed that yeast lipid biodiversity has not been fully explored, but that yeasts likely harbor as-yet-undiscovered strains or enzymes that can contribute to the production of high-value fatty acids for green chemistry

Ex vivo lentivirus transduction and immediate transplantation of uncultured hepatocytes for treating hyperbilirubinemic Gunn rat

Ex vivo liver gene therapy provides an attractive alternative to orthotopic liver transplantation for the treatment of liver diseases. We previously reported a protocol in which human primary hepatocytes are highly transduced in Suspension with Lentiviral vectors and Immediately Transplanted (SLIT). Here, we evaluated the SLIT approach in Gunn rats, the animal model for Crigler-Najjar syndrome type 1, a defect in bilirubin UDP-glucuronosyltransferase (BUGT)