miRNPs: a novel class of ribonucleoproteins containing numerous microRNAs

Gemin3 is a DEAD-box RNA helicase that binds to the Survival of Motor Neurons (SMN) protein and is a component of the SMN complex, which also comprises SMN, Gemin2, Gemin4, Gemin5, and Gemin6. Reduction in SMN protein results in Spinal muscular atrophy (SMA), a common neurodegenerative disease. The SMN complex has critical functions in the assembly/restructuring of diverse ribonucleoprotein (RNP) complexes. Here we report that Gemin3 and Gemin4 are also in a separate complex that contains eIF2C2, a member of the Argonaute protein family. This novel complex is a large approximately 15S RNP that contains numerous microRNAs (miRNAs). We describe 40 miRNAs, a few of which are identical to recently described human miRNAs, a class of small endogenous RNAs. The genomic sequences predict that miRNAs are likely to be derived from larger precursors that have the capacity to form stem-loop structures.     

Impact of HLA-C and Bw epitopes disparity on liver transplantation outcome

The occurrence of graft rejection episodes after orthotopic liver transplantation (OLT) despite the use of immunosuppressive drugs designed to suppress T lymphocyte functions, indicates the involvement of other types of cells in this process. The activity of natural killer cells and their killer immunoglobulin-like receptors (KIR) is regulated by human leukocyte antigen (HLA) class I determinants; C and Bw epitopes. Because recipient/donor pairs are usually HLA mismatched, recipient natural killer alloreactivity may be the mediating factor in rejection. In this retrospective study, we have analyzed rejection occurrence and outcome in 66 OLT recipients, 42 with and 24 without C or Bw epitope disparity in the rejection direction. Recipients transplanted from donors with no C epitope disparity had significantly fewer rejection episodes in the first year after transplantation compared with recipients transplanted across C epitope disparity (p = 0.0002). Moreover, this effect was more pronounced when the outcome was analyzed in OLT recipients across negative crossmatching for the anti-HLA class I and II antibodies. In contrast, Bw epitope disparity did not affect the outcome. In conclusion, C epitopes disparity between recipients and donors in the rejection direction appears to influence posttransplant liver outcome. This finding may be helpful in the choice of appropriate liver donor and planning immune suppression.     

Safety of vaginal delivery in very low birthweight vertex singletons: a meta-analysis

Objective: The objective of this study is to assess the safety of vaginal delivery in VLBW singletons in the vertex presentation.

Methods: MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and Web of Science databases were searched for studies on mode of delivery and neonatal outcome in VLBW singletons in the vertex presentation. A total of 28 studies met our inclusion criteria.

Results: Vaginal delivery was not associated with an increase in overall neonatal mortality compared with cesarean delivery (OR 0.87, 95% CI 0.72–1.04). Vaginal delivery was associated with a significant decrease in mortality for the 1250–1500?g birthweight category (OR 0.57, 95% CI 0.36–0.92), while an increase in mortality in the 500–750?g category was not significant (OR 1.5, 95% CI 0.86–2.61). Severe intraventricular hemorrhage (IVH) was not associated with mode of delivery (OR 1.05, 95% CI 0.85–1.29), but the only two high quality study that assessed IVH of all grades found an increase in risk for IVH in vaginal delivery (OR 1.33, 95% CI 1.16–1.51).

Conclusions: Vaginal delivery does not appear to increase the risk for neonatal mortality. However, current available data on neonatal morbidity are limited. More high-quality studies are needed to assess the association between mode of delivery and neonatal morbidity.     

Malabsorption may contribute to malnutrition in the elderly

Malnutrition, either actually malnourished or at risk, is present in 80% of the elderly population presenting to hospital for admission. Although many factors contribute to this situation, one yet to be explored is malabsorption. We therefore aimed to assess nutritional status as well as the prevalence of altered mucosal permeability and celiac disease among a group of elderly patients presenting for rehabilitation. Forty-eight subjects were recruited (16 females) with a mean age of 83.7 (SD 6.1), body mass index 21.8 kg/m² (SD 3.9), mini-nutritional assessment (MNA) 19.5 (SD 3.4). They had no current gastrointestinal symptoms and undertook an assessment of mucosal permeability using the dual sugar absorption test of lactulose (7.5 g) and rhamnose (1 g). Ten of the 48 subjects had increased mucosal permeability with an L:R ration ranging from 0.0860 to 7.706 (N 0.01–0.08). These subjects were all at risk or malnourished according to the MNA score and they had a significantly lower mean MNA score of 17.2 (SD 3.5) compared to normal absorbers with a mean of 19.5 (SD 3.4). Two of the subjects had positive tissue trans-glutaminase antibodies. The higher risk of potential malabsorption in this elderly population has significant implications both for nutritional supplementation and for drug absorption as well as being a possible major contributor to malnutrition.     

A founder truncating variant in GDF1 causes autosomal‐recessive right isomerism and associated congenital heart defects in multiplex Arab kindreds

The genetic basis of congenital heart malformations associated with disruption of left–right (L–R) asymmetry is broad and heterogenous, with variants in over 25 genes implicated thus far. Of these, deleterious variants in the Growth/Differentiation Factor 1 (GDF1) gene have been shown to cause heterotaxy with varied complex heart malformations of left–right patterning, in 23 individuals reported to date, either in monoallelic or biallelic state. We report three unrelated individuals exhibiting right isomerism with congenital heart defects, each originating from a consanguineous kindred of Arab‐Muslim descent. Using whole exome sequencing, a shared novel homozygous truncating c.608G > A (p.W203*) variant in the GDF1 gene was revealed as the molecular basis of their disease. Subsequently, targeted sequencing of this variant showed full segregation with the disease in these families, with a total of over 15 reportedly affected individuals, enabling genetic counseling, prenatal diagnosis, and planning of future pregnancies. Our findings further confirm the association of biallelic GDF1 variants, heterotaxy and congenital heart defects of left–right patterning, and expand the previously described phenotypic spectrum and mutational profile. Moreover, we suggest targeted screening for the p.W203* variant in relevant clinical circumstances.     

Epicutaneous sensitization in the development of food allergy: What is the evidence and how can this be prevented?

There is increasing evidence regarding the importance of allergic sensitization through the skin. In this review, we provide an overview of the atopic march and immune mechanism underlying the sensitization and effector phase of food allergy. We present experimental models and human data that support the concept of epicutaneous sensitization and how this forms one half of the dual-allergen exposure hypothesis. We discuss specific important elements in the skin (FLG and other skin barrier gene mutations, Langerhans cells, type 2 innate lymphoid cells, IL-33, TSLP) that have important roles in the development of allergic responses as well as the body of evidence on environmental allergen exposure and how this can sensitize an individual. Given the link between skin barrier impairment, atopic dermatitis, food allergy, allergic asthma, and allergic rhinitis, it is logical that restoring the skin barrier and prevention or treating atopic dermatitis would have beneficial effects on prevention of related allergic diseases, particularly food allergy. We present the experimental and human studies that have evaluated this approach and discuss various factors which may influence the success of these approaches, such as the type of emollient chosen for the intervention, the role of managing skin inflammation, and differences between primary and secondary prevention of atopic dermatitis to achieve the desired outcome.     

Involvement of the IP3 cascade in the damage to guinea-pig ventricular myocytes induced by cytotoxic T lymphocytes

 We have shown previously that the interaction between cytotoxic T lymphocytes (CTL) and ventricular myocytes, an in vitro model for heart transplant rejection, results in electrophysiological and morphological alterations indicative of overload of the intracellular [Ca²⁺] ([Ca²⁺]_i). Since these deleterious effects cannot be accounted for by increased L-type Ca²⁺ current (I _Ca,L), we hypothesize that [Ca²⁺]_i overload due to Ca²⁺ release from intracellular stores, e.g. sarcoplasmic reticulum (SR), is initiated by CTL-induced activation of the inositol trisphosphate (IP₃) cascade. Patch-clamp and fura-2-fluorescence techniques were utilized to record transmembrane potentials and [Ca²⁺]_i from ventricular myocytes bound to peritoneal exudate CTL (PEL). In ventricular myocyte-PEL conjugates (after 60 min), resting potential was reduced (compared with the nonconjugated state) from –80.9 ± 0.7 to –59.9 ± 2.5 mV, action potential amplitude from 139.5 ± 1.4 to 80.6 ± 1.7 mV and action potential duration to 50% repolarization (APD₅₀) from 797 ± 97 to 52 ± 12 ms. The ratio of fluorescence at 340 and 380 nm (R _340/380) increased from a control value (in nonconjugated myocytes) of 0.71 ± 0.02 to 2.07 ± 0.03, 30 min after conjugate formation, and exceeded 4.0 at 60 min, before myocyte destruction. Heparin (50 μg/ml), an antagonist of IP₃-induced Ca²⁺ release from SR channels, or U-73122 (2 μM), a phospholipase C (PLC) inhibitor (drugs were included in the pipette solution), prevented PEL-induced morphological and electrophysiological alterations. Accordingly, heparin attenuated the PEL-induced increase in [Ca²⁺]_i; after 60 min of PEL-myocyte interaction, R _340/380 was 1.15 ± 0.09 (compared with approximately 4.0 in the absence of heparin). The results indicate that CTL-mediated damage to ventricular myocytes is, at least partially, mediated by PLC activation and IP₃-induced Ca²⁺ release from intracellular stores. Pharmacological targeting of IP₃ in heart transplant rejection is thus suggested. Received: 3 July 1996 / Received after revision: 21 October 1996 / Accepted: 3 December 1996     

Mosaicism of the CAG repeat sequence in the Huntington disease gene in a pair of monozygotic twins

We report on a pair of monozygotic twins belonging to a family segregating Huntington disease (HD). In routine DNA analysis of blood cells, they displayed three alleles of the CAG repeat sequence in the HD gene. Two different cell lines, carrying the normal allele together with either an expanded allele with 47 CAGs or an intermediate allele with 37 CAGs, were detected in blood and buccal epithelium from both twins. To our knowledge, this is the first case described of HD gene CAG repeat length mosaicism in blood cells. Haplotype analysis established that the 37 CAG allele most likely arose by contraction of the maternal 47 CAG allele. The contraction must have taken place postzygotically, possibly at a very early stage of development, and probably before separation of the twins. One of the twins has presented symptoms of HD for 4 years; his skin fibroblasts and hair roots carried only the cell line with the 47 CAG repeat allele. The other twin, who is without symptoms at present, displayed mosaicism in skin fibroblasts and hair roots. If the proportion of the two cell lines in the brain of each twin resembles that of their hair roots (another tissue originating from the ectoderm), the mosaicism in the unaffected twin would mean that only a part of his brain cells carried the expanded allele, which could explain why he, in contrast to his brother, has no symptoms at this time.     

Heparanase enhances early hepatocyte inclusion in the recipient liver after transplantation in partially hepatectomized rats

Hepatocyte transplantation is an emerging approach for the treatment of liver diseases. However, broad clinical application of this method has been limited by restricted source of cells and low efficiency of cell integration within the recipient liver. Heparanase cleaves heparan sulfate proteoglycans in the extracellular matrix and basement membrane, activity that affects cellular invasion associated with cancer metastasis and inflammation. This activity has a multifunctional effect on cell-cell interaction, cell adhesion, and angiogenesis. All these factors are important for successful integration of transplanted hepatocytes. Male donor hepatocytes pretreated with heparanase or untreated were transplanted into recipient female rat spleen following partial hepatectomy. Engraftment efficacy was evaluated by PCR for Y chromosome, histology and PCNA, and heparanase immunohistochemistry. In addition, proliferative activity of hepatocytes in vitro was determined by bromodeoxyuridine immunostaining. The number of heparanase-treated cells detected in the recipient liver was significantly increased three- to fivefold within 24-48 h posttransplantation and twofold at 14 days compared with untreated cells. The transplanted hepatocytes treated with heparanase were clearly seen inside portal vein radicles as cell aggregates up to 72 h posttransplantation. The number of portal radicles filled with heparanase-treated hepatocytes was increased compared to control early after transplantation. Heparanase treatment enhanced hepatocyte and sinusoidal endothelial cell proliferation in the liver, and hepatocyte proliferation within the spleen tissue. Preliminary in vitro studies with isolated hepatocytes treated with heparanase showed increased proliferative activity within 24-48 h of cell culture. These results suggest that preincubation of hepatocytes with heparanase increases the presence of hepatocytes within the recipient liver early following cell transplantation and stimulates both hepatocyte and sinusoidal endothelial cell proliferation.