Myocardial volume and organization are changed by failure of addition of secondary heart field myocardium to the cardiac outflow tract.

Cardiac neural crest ablation results in primary myocardial dysfunction and failure of the secondary heart field to add the definitive myocardium to the cardiac outflow tract. The current study was undertaken to understand the changes in myocardial characteristics in the heart tube, including volume, proliferation, and cell size when the myocardium from the secondary heart field fails to be added to the primary heart tube. We used magnetic resonance and confocal microscopy to determine that the volume of myocardium in the looped heart was dramatically reduced and the compact layer of myocardium was thinner after neural crest ablation, especially in the outflow tract and ventricular regions. Proliferation measured by 5-bromo-2'-deoxyuridine incorporation was elevated at only one stage during looping, cell death was normal and myocardial cell size was increased. Taken together, these results indicate that there are fewer myocytes in the heart. By incubation day 8 when the heart would have normally completed septation, the anterior (ventral) wall of the right ventricle and right ventricular outflow tract was significantly thinner in the neural crest-ablated embryos than normal, but the thickness of the compact myocardium was normal in all other regions of the heart. The decreased volume and number of myocardial cells in the heart tube after neural crest ablation most likely reflects the amount of myocardium added by the secondary heart field.     

Identification and characterization of mutations in FANCL gene: A second case of Fanconi anemia belonging to FA‐L complementation group

Fanconi anemia (FA) is a rare autosomal recessive or X‐linked disorder characterized by aplastic anemia, cancer susceptibility and cellular sensitivity to DNA crosslinking agents. Eight FA proteins (FANCA, FANCB, FANCC, FANCE, FANCF, FANCG, FANCL and FANCM) and three non‐FA proteins (FAAP100, FAAP24 and HES1) form an FA nuclear core complex, which is required for monoubiquitination of the FANCD2‐FANCI dimer upon DNA damage. FANCL possesses a PHD/RING‐finger domain and is a putative E3 ubiquitin ligase subunit of the core complex. In this study, we report an FA patient with an unusual presentation belonging to the FA‐L complementation group. The patient lacks an obvious FA phenotype except for the presence of a café‐au‐lait spot, mild hypocellularity and a family history of leukemia. The molecular diagnosis and identification of the FA subgroup was achieved by FA complementation assay. We identified bi‐allelic novel mutations in the FANCL gene and functionally characterized them. To the best of our knowledge, this is the second reported case belonging to the FA‐L complementation group. © 2009 Wiley‐Liss, Inc.     

Antenatal betamethasone and favourable outcomes in fetuses with `poor prognosis' diaphragmatic hernia

 Congenital diaphragmatic hernia (CDH) is a common abnormality affecting 1 in 2,000 gestations. The mortality exceeds 50% despite recent advances in postnatal treatment. The widespread antenatal use of glucocorticoids to induce lung maturation in fetuses at risk of premature delivery suggests a potential for a therapeutic effect in other fetuses with impaired lung development. The parents of three fetuses referred with CDH and features suggesting a poor postnatal prognosis (early diagnosis, liver herniation, and lung area-to-head circumference ratio <1.0, or associated abnormalities) elected to receive maternal betamethasone starting at 24 to 26 weeks' gestation rather than undergo a fetal tracheal plug. All three infants survived and were extubated within 10 days. The long-term use of antenatal steroids in the treatment of CDH may thus be of benefit and warrants further study. Accepted: 26 February 2001     

Sex determination in platypus and echidna: autosomal location of <Emphasis Type="Italic">SOX3</Emphasis> confirms the absence of <Emphasis Type="Italic">SRY</Emphasis> from monotremes

In eutherian ('placental') mammals, sex is determined by the presence or absence of the Y chromosome-borne gene SRY, which triggers testis determination. Marsupials also have a Y-borne SRY gene, implying that this mechanism is ancestral to therians, the SRY gene having diverged from its X-borne homologue SOX3 at least 180 million years ago. The rare exceptions have clearly lost and replaced the SRY mechanism recently. Other vertebrate classes have a variety of sex-determining mechanisms, but none shares the therian SRY-driven XX female:XY male system. In monotreme mammals (platypus and echidna), which branched from the therian lineage 210 million years ago, no orthologue of SRY has been found. In this study we show that its partner SOX3 is autosomal in platypus and echidna, mapping among human X chromosome orthologues to platypus chromosome 6, and to the homologous chromosome 16 in echidna. The autosomal localization of SOX3 in monotreme mammals, as well as non-mammal vertebrates, implies that SRY is absent in Prototheria and evolved later in the therian lineage 210-180 million years ago. Sex determination in platypus and echidna must therefore depend on another male-determining gene(s) on the Y chromosomes, or on the different dosage of a gene(s) on the X chromosomes.     

Bronchitis symptoms in young teenagers who actively or passively smoke cigarettes

This study was undertaken to examine the prevalence of bronchitis (cough with phlegm) symptoms in teenagers who either smoked cigarettes on a regular basis (active smokers) or were non-smokers but who are exposed to passive smoking (passive smokers) in the home. The study was undertaken in 1995 and repeated in 1998. The 1995 study was a cross sectional questionnaire survey of smoking habits in secondary school children aged 13-14 years and was undertaken as part of the ISAAC questionnaire survey. Thirty representative and randomly selected schools from throughout the Republic of Ireland took part in the study. In the 1995 study, 3066 students completed a questionnaire on their current smoking habits and symptoms of cough and phlegm. We found that 634 (20.7%) of these young teenagers actively smoked cigarettes with significantly more females smoking than males with 23.3% of girls compared to 17.6% boys (p = 0.0001). We found that 46.3% of non-smoking children were exposed to smoking in the home (passive smokers) with parental smoking accounting for most of the passive smoking. Bronchitis symptoms were more commonly reported in active smokers compared to non-smokers with an odds ratio of 3.02 (95% CI 2.34-3.88) (p < 0.0001) or in passive smokers compared to those not exposed to smoking with odds ratio of 1.82 (95% CI 1.32-2.52) (p < 0.0001). The 1998 study showed similar results for smoking habits, passive smoking and prevalence of bronchitis symptoms as with the 1995 study. These results document that increased bronchitis symptoms occur in teenagers exposed to active or passive smoking.     

The immunology of primary biliary cirrhosis: the end of the beginning?

The chronic liver disease primary biliary cirrhosis (PBC) is characterised by autoreactive B‐cell and T‐cell responses directed against mitochondrial antigens. In recent years these responses have been extensively characterised and the principal PBC associated autoantigen identified as pyruvate dehydrogenase complex (PDC). The identification of anti‐PDC responses (present in over 95% of PDC patients) has given rise to important questions pertinent to our understanding of the pathogenesis of PBC. What specific role to anti‐PDC responses play in target cell damage? How and why does immune tolerance break down to as highly conserved and ubiquitously expressed self‐antigen as PDC? Why does breakdown in tolerance to an antigen present in all nucleated cells result in damage restricted to the intra‐hepatic bile ducts? In attempting to answer these key questions we have, in this review, proposed a unifying hypothesis for the pathogenesis of PBC.     

TNFα Inhibitors in the Treatment of Psoriasis and Psoriatic Arthritis

Psoriasis is a chronic inflammatory skin disease that can lead to significant physical and psychologic distress for patients. Psoriatic arthritis (PsA), originally thought to be quite a mild disorder, is now recognized as a progressive and destructive arthritis. To date, therapies for both these conditions have been non-specific and unable to maintain long-lasting remission. In addition, many of the current therapies have significant adverse effects, limiting their usefulness. However, elucidation of the pathogenesis of psoriasis and PsA at a molecular level and the development of selective biologic agents have led to an enormous expansion of the armamentarium available to psoriasis patients. Two agents (infliximab and etanercept) selectively block the role of the cytokine tumor necrosis factor (TNF)-alpha and have proved effective in clinical trials in the treatment of both the skin and the joint manifestations of psoriasis. A third anti-TNF alpha agent (adalimumab Humira) is licensed for the treatment of rheumatoid arthritis; however, no studies have been published to date on its use in PsA or psoriasis. It is known that TNF alpha is elevated in both the skin and synovium of psoriatic patients and the effectiveness of its blockade by these two agents in psoriasis and PsA confirms its role in their pathogenesis. Randomized, double-blind, placebo-controlled trials have been performed with both agents in the treatment of psoriasis and PsA; in the case of etanercept these have been to support US FDA approval for use in psoriatic arthropathy. These studies are supported by smaller cohorts in open-label studies and anecdotal reports in the literature. Anti-TNF alpha therapy has proved to have disease-reducing activity in PsA and psoriasis and appears to be well tolerated. These studies have generally featured small numbers of patients and, until a larger cohort of treated patients is available, vigilance must be exercised. A considerable body of post-marketing safety data exists on the use of infliximab in rheumatoid arthritis and Crohn disease and for etanercept in rheumatoid arthritis and PsA. Certain issues, particularly the risk of infection, have emerged as features of the use of these agents. It remains to be seen whether effects seen in other disease entities may be extrapolated to psoriatic patients. More long-term data and experience are needed to define the role of anti-TNF alpha agents in the management of psoriasis and PsA. In particular, more studies are required to elucidate the finer points of co-medication; in some studies both agents have been used with other medications but there have been no formal trials of various possible combinations.     

Autosomal location of genes from the conserved mammalian X in the platypus (<Emphasis Type="Italic">Ornithorhynchus anatinus</Emphasis>): implications for mammalian sex chromosome evolution

Mammalian sex chromosomes evolved from an ancient autosomal pair. Mapping of human X- and Y-borne genes in distantly related mammals and non-mammalian vertebrates has proved valuable to help deduce the evolution of this unique part of the genome. The platypus, a monotreme mammal distantly related to eutherians and marsupials, has an extraordinary sex chromosome system comprising five X and five Y chromosomes that form a translocation chain at male meiosis. The largest X chromosome (X₁), which lies at one end of the chain, has considerable homology to the human X. Using comparative mapping and the emerging chicken database, we demonstrate that part of the therian X chromosome, previously thought to be conserved across all mammals, was lost from the platypus X₁ to an autosome. This region included genes flanking the XIST locus, and also genes with Y-linked homologues that are important to male reproduction in therians. Since these genes lie on the X in marsupials and eutherians, and also on the homologous region of chicken chromosome 4, this represents a loss from the monotreme X rather than an additional evolutionary stratum of the human X.     

Reduced pregnancy rates following the transfer of human embryos frozen or thawed in culture media supplemented with normal serum albumin

Over a 26 month period 17% of couples having treatment in our clinical programmes selected a commercially available protein (normal serum albumin, NSA) prepared from pooled human sera instead of using their own serum as a supplement for their embryo culture media. In a retrospective analysis of >2000 gonadotrophin-stimulated cycles and 1000 cycles where frozen/thawed embryos were transferred, fertilization, embryo quality and pregnancy rates following in-vitro fertilization (IVF), gamete intra-Fallopian transfer (GIFT) or intracytoplasmic sperm injection (ICSI) were unaffected by the type of protein used to supplement the culture medium. When embryos were thawed in medium containing NSA, both pregnancy (PR) and implantation rates (IR) were significantly lower (P <0.05) than if the medium was supplemented with serum (PR 8.3% and 17.5%; IR 4.6% and 10.5%). Inclusion of NSA before freezing reduced the IR of thawed embryos. To further test this observation all cycles where embryos were cultured and frozen in medium containing NSA (173 cycles) were matched to cycles where serum was used and the outcome was compared. At the end of 1995 just over half of the embryos in both groups had been thawed. No statistical difference was noted in the pregnancy rates (NSA, 5.6% versus serum, 11.3%) but the IR per embryo was significantly lower when embryos were cultured and frozen in medium supplemented with NSA (2.2%) than when serum was used as the supplement (6.6%).