Ionic mechanisms of electrical remodeling in human atrial fibrillation

OBJECTIVES

Atrial fibrillation (AF) is associated with a decrease in atrial ERP and ERP adaptation to rate as well as changes in atrial conduction velocity. The cellular changes in repolarization and the underlying ionic mechanisms in human AF are only poorly understood.

METHODS

Action potentials (AP) and ionic currents were studied with the patch clamp technique in single atrial myocytes from patients in chronic AF and compared to those from patients in stable sinus rhythm (SR).

RESULTS

The presence of AF was associated with a marked shortening of the AP duration and a decreased rate response of atrial repolarization. L-type calcium current (ICa,L) and the transient outward current (Ito) were both reduced about 70% in AF, whereas an increased steady-state outward current was detectable at test potentials between -30 and 0 mV. The inward rectifier potassium current (IKI) and the acetylcholine-activated potassium current (IKACh) were increased in AF at hyperpolarizing potentials. Voltage-dependent inactivation of the fast sodium current (INa) was shifted to more positive voltages in AF.

CONCLUSIONS

AF in humans leads to important changes in atrial potassium and calcium currents that likely contribute to the decrease in APD and APD rate adaptation. These changes contribute to electrical remodeling in AF and are therefore important factors for the perpetuation of the arrhythmia.

A freely diffusible form of Sonic hedgehog mediates long-range signalling

The secreted protein Sonic hedgehog (Shh) exerts many of its patterning effects through a combination of short- and long-range signalling. Three distinct mechanisms, which are not necessarily mutually exclusive, have been proposed to account for the long-range effects of Shh: simple diffusion of Shh, a relay mechanism in which Shh activates secondary signals, and direct delivery of Shh through cytoplasmic extensions, termed cytonemes. Although there is much data (using soluble recombinant Shh (ShhN)) to support the simple diffusion model of long-range Shh signalling, there has been little evidence to date for a native form of Shh that is freely diffusible and not membrane-associated. Here we provide evidence for a freely diffusible form of Shh (s-ShhNp) that is cholesterol modified, multimeric and biologically potent. We further demonstrate that the availability of s-ShhNp is regulated by two functional antagonists of the Shh pathway, Patched (Ptc) and Hedgehog-interacting protein (Hip). Finally, we show a gradient of s-ShhNp across the anterior-posterior axis of the chick limb, demonstrating the physiological relevance of s-ShhNp.

DNA polymerase eta is an A-T mutator in somatic hypermutation of immunoglobulin variable genes

To determine whether DNA polymerase eta plays a role in the hypermutation of immunoglobulin variable genes, we examined the frequency and pattern of substitutions in variable VH6 genes from the peripheral blood lymphocytes of three patients with xeroderma pigmentosum variant disease, whose polymerase eta had genetic defects. The frequency of mutation was normal but the types of base changes were different: there was a decrease in mutations at A and T and a concomitant rise in mutations at G and C. We propose that more than one polymerase contributes to hypermutation and that if one is absent, others compensate. The data indicate that polymerase eta is involved in generating errors that occur predominantly at A and T and that another polymerase(s) may preferentially generate errors opposite G and C.

MDM2 suppresses p73 function without promoting p73 degradation

The newly identified p53 homolog p73 can mimic the transcriptional activation function of p53. We investigated whether p73, like p53, participates in an autoregulatory feedback loop with MDM2. p73 bound to MDM2 both in vivo and in vitro. Wild-type but not mutant MDM2, expressed in human p53 null osteosarcoma Saos-2 cells, inhibited p73- and p53-dependent transcription driven by the MDM2 promoter-derived p53RE motif as measured in transient-transfection and chloramphenicol acetyltransferase assays and also inhibited p73-induced apoptosis in p53-null human lung adenocarcinoma H1299 cells. MDM2 did not promote the degradation of p73 but instead disrupted the interaction of p73, but not of p53, with p300/CBP by competing with p73 for binding to the p300/CBP N terminus. Both p73alpha and p73beta stimulated the expression of the endogenous MDM2 protein. Hence, MDM2 is transcriptionally activated by p73 and, in turn, negatively regulates the function of this activator through a mechanism distinct from that used for p53 inactivation.

A DNA damage-induced p53 serine 392 kinase complex contains CK2, hSpt16, and SSRP1

Phosphorylation of the human p53 protein at Ser-392 has been shown to be responsive to UV but not gamma irradiation. Here we describe identification and purification of a mammalian UV-activated protein kinase complex that phosphorylates Ser-392 of p53 in vitro. This kinase complex contains casein kinase 2 (CK2) and the chromatin transcriptional elongation factor FACT (a heterodimer of hSpt16 and SSRP1). In vitro studies show that FACT alters the specificity of CK2 in the complex such that it selectively phosphorylates p53 over other substrates including casein. In addition, phosphorylation by the kinase complex enhances p53 activity. These results thus provide a potential mechanism for p53 activation by UV irradiation.

CXC chemokine receptor CXCR2 is essential for protective innate host response in murine Pseudomonas aeruginosa pneumonia

Pulmonary infection due to Pseudomonas aeruginosa has emerged as a leading cause of mortality. A vigorous host response is required to effectively clear the organisms from the lungs. This host defense is dependent on the recruitment and activation of neutrophils and macrophages. A family of chemotactic cytokines (chemokines) has been shown to participate in this protective response. In this study, we assessed the role of the ELR(+) (glutamic acid-leucine-arginine motif positive) CXC chemokines and their CXC chemokine receptor (CXCR2) in lung antibacterial host defense. The intratracheal administration of Pseudomonas to mice resulted in the time-dependent influx of neutrophils to the lung, peaking at 12 to 24 h after inoculation. The influx of neutrophils was associated with a similar time-dependent expression of the ELR(+) CXC chemokines, KC, macrophage inflammatory protein 2 (MIP-2), and lipopolysaccharide-induced CXC chemokine (LIX). Selective neutralization of MIP-2 or KC resulted in modest changes in neutrophil influx but no change in bacterial clearance or survival. However, neutralization of CXCR2 resulted in a striking increase in mortality, which was associated with a marked decrease in neutrophil recruitment and bacterial clearance. Conversely, the site-specific transgenic expression of KC resulted in enhanced clearance of bacteria after Pseudomonas challenge. This study indicates that ELR(+) CXC chemokines are critical mediators of neutrophil-mediated host defense in Pseudomonas pneumonia.

Early recruitment of neutrophils determines subsequent T1/T2 host responses in a murine model of Legionella pneumophila pneumonia

The contribution of neutrophils to lethal sensitivity and cytokine balance governing T1 and T2 host responses was assessed in a murine model of Legionella pneumophila pneumonia. Neutrophil depletion by administration of granulocyte-specific mAb RB6-8C5 at 1 day before infection rendered mice approximately 100-fold more susceptible to lethal pneumonia induced by L. pneumophila. However, this treatment did not alter early bacterial clearance, despite a substantial decrease in neutrophil influx at this time point. Cytokine profiles in the lungs of control mice demonstrated strong T1 responses, characterized by an increase of IFN-gamma and IL-12. In contrast, neutrophil-depleted mice exhibited significantly lower levels of IFN-gamma and IL-12, and elevation of T2 cytokines, IL-4 and IL-10. Immunohistochemistry of bronchoalveolar lavage cells demonstrated the presence of IL-12 in neutrophils, but not alveolar macrophages. Moreover, IL-12 was detected in lavage cell lysates by ELISA, which was paralleled to neutrophil number. However, intratracheal administration of recombinant murine IL-12 did not restore resistance, whereas reconstitution of IFN-gamma drastically improved bacterial clearance and survival in neutrophil-depleted mice. Taken together, these data demonstrated that neutrophils play crucial roles in primary L. pneumophila infection, not via direct killing but more immunomodulatory effects. Our results suggest that the early recruitment of neutrophils may contribute to T1 polarization in a murine model of L. pneumophila pneumonia.

Resveratrol regulates mitochondrial reactive oxygen species homeostasis through Sirt3 signaling pathway in human vascular endothelial cells

Mitochondrial reactive oxygen species (mtROS) homeostasis plays an essential role in preventing oxidative injury in endothelial cells, an initial step in atherogenesis. Resveratrol (RSV) possesses a variety of cardioprotective activities, however, little is known regarding the effects of RSV on mtROS homeostasis in endothelial cells. Sirt3 is a mitochondrial deacetylase, which plays a key role in mitochondrial bioenergetics and is closely associated with oxidative stress. The goal of the study is to investigate whether RSV could attenuate oxidative injury in endothelial cells via mtROS homeostasis regulation through Sirt3 signaling pathway. We found that pretreatment with RSV suppressed tert-butyl hydroperoxide (t-BHP)-induced oxidative damage in human umbilical vein endothelial cells (HUVECs) by increasing cell viability, inhibiting cell apoptosis, repressing collapse of mitochondrial membrane potential and decreasing mtROS generation. Moreover, the enzymatic activities of isocitrate dehydrogenase 2 (IDH2), glutathione peroxidase (GSH-Px) and manganese superoxide dismutase (SOD2) as well as deacetylation of SOD2 were increased by RSV pretreatment, suggesting RSV notably enhanced mtROS scavenging in t-BHP-induced endothelial cells. Meanwhile, RSV remarkably reduced mtROS generation by promoting Sirt3 enrichment within the mitochondria and subsequent upregulation of forkhead box O3A (FoxO3A)-mediated mitochondria-encoded gene expression of ATP6, CO1, Cytb, ND2 and ND5, thereby leading to increased complex I activity and ATP synthesis. Furthermore, RSV activated the expressions of phosphorylated adenosine monophosphate-activated protein kinase (p-AMPK), peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) and Sirt3, as well as estrogen-related receptor-α (ERRα)-dependent Sirt3 mRNA transcription, which were abolished in the presence of AMPK inhibitor and AMPK, PGC-1α or Sirt3 siRNA transfection, indicating the effects of RSV on mtROS homeostasis regulation were dependent on AMPK-PGC-1α-ERRα-Sirt3 signaling pathway. Our findings indicated a novel mechanism that RSV-attenuated oxidative injury in endothelial cells through the regulation of mtROS homeostasis, which, in part, was mediated through the activation of the Sirt3 signaling pathway.

MDM2 inhibits p300-mediated p53 acetylation and activation by forming a ternary complex with the two proteins

p300 acetylates and activates the tumor suppressor p53 after DNA damage. Here, we show that MDM2, a negative-feedback regulator of p53, inhibited p300-mediated p53 acetylation by complexing with these two proteins. First, we purified a p300-MDM2-p53 protein complex from HeLa nuclear extracts, which was inactive in p53 acetylation, but active in histone acetylation. Also, wild-type, but not N-terminally deleted, MDM2 inhibited p53 acetylation by p300 in vitro and in vivo. This inhibition was specific for p53, because MDM2 did not affect acetylation of histones or the C terminus of p73 by p300. Consequently, wild-type, but not the mutant, MDM2 repressed the p300-stimulated sequence-specific DNA-binding and transcriptional activities of p53. These results demonstrate that an additional mechanism of p53 inactivation by MDM2 is to inhibit p53 acetylation by p300.

VEGF enhances pulmonary vasculogenesis and disrupts lung morphogenesis in vivo

Vascular endothelial growth factor (VEGF) was expressed in developing respiratory epithelial cells under control of the promoter from the human surfactant protein C (SP-C) gene. SP-C-VEGF transgenic mice did not survive after birth. When obtained by hysterectomy on embryonic day 15 (E15) or 17 (E17), abnormalities in the transgenic mice were confined to the lung and were correlated with the expression of transgene mRNA as revealed by in situ hybridization. On E15 and E17, marked abnormalities in lung morphogenesis were observed in transgenic mice. Lungs consisted of large dilated tubules with increased peritubular vascularity. The mRNA levels of the VEGF receptor, Flk-1, and the endothelial cell specific receptor tyrosine kinase, Tie-1, were increased in lung mesenchyme of the transgenic mice. The numbers of acinar tubules and the abundance of mesenchyme were decreased. Endogenous VEGF mRNA was expressed in the respiratory epithelial cells of the developing lungs, and the levels of VEGF mRNA were increased in the SP-C-VEGF transgenic mice. Although the normal pattern of immunostaining for SP-C and Clara cell secretory protein (CCSP) indicated that epithelial cell differentiation was relatively unaltered by the transgene, electron microscopic analysis revealed a lack of alveolar Type I cell differentiation at E18. Expression of VEGF in the developing respiratory epithelium of transgenic mice increased growth of the pulmonary blood vessels, disrupted branching morphogenesis of the lung and inhibited Type I cell differentiation.

Membrane chromatography: preparation and applications to protein separation

As a result of the convective flow of solutes through porous membranes, membrane chromatography has a higher capture efficiency and a higher productivity than column chromatography and shows most promising industrial applications for the recovery, isolation, and purification of proteins and enzymes. This paper presents a comprehensive review of the methods for preparation of adsorptive membranes (such as surface modification, in situ copolymerization, direct formation from hydrophilic materials, and functionalized particulate-entrapped membranes) and deals particularly with novel macroporous chitin and chitosan membranes for protein separations developed by the authors.

Nanosecond and femtosecond laser ablation of brass: particulate and ICPMS measurements

Femtosecond and nanosecond lasers were compared for ablating brass alloys. All operating parameters from both lasers were equal except for the pulse duration. The ablated aerosol vapor was collected on silicon substrates for particle size measurements or sent into an inductively coupled plasma mass spectrometer. The diameters and size distribution of particulates were measured from scanning electron microscope (SEM) images of the collected ablated aerosol. SEM measurements showed that particles ablated using nanosecond pulses were single spherical entities ranging in diameter from several micrometers to several hundred nanometers. Primary particles ablated using femtosecond ablation were approximately 100 nm in diameter but formed large agglomerates. ICPMS showed enhanced signal intensity and stability using femtosecond compared to nanosecond laser ablation.

Hepatocyte nuclear factor 4alpha attenuates hepatic fibrosis in rats

BACKGROUND AND AIMS

Hepatocyte nuclear factor 4alpha (HNF4alpha) is a central transcriptional regulator of hepatocyte differentiation and function. The aim of this study was to evaluate the effect of HNF4alpha on attenuation of hepatic fibrosis.

METHODS

The adenoviruses carrying HNF4alpha gene or containing siRNA targeting HNF4alpha were injected through tail vein on two distinct hepatic fibrosis models either induced by dimethylnitrosamine or by bile duct ligation in rats. Moreover, HNF4alpha, epithelial-mesenchymal transition (EMT)-related and fibrotic markers in hepatocytes, hepatic stellate cells (HSCs) and liver tissues were detected by real time PCR, immunofluorescence or immunohistochemistry.

RESULTS

We demonstrated that decreased expression of HNF4alpha and epithelial markers accompanied by enhanced expression of mesenchymal markers occurred in fibrotic liver. More importantly, forced expression of HNF4alpha remarkably alleviated hepatic fibrosis and improved liver function with suppression of EMT in both fibrosis models. In contrast, downregulation of HNF4alpha by siRNA aggravated hepatic fibrosis and decreased the expression of E-cadherin in association with the enhanced expression of vimentin and fibroblast-specific protein-1. In vitro study revealed that HNF4alpha could suppress the EMT process of hepatocytes induced by transforming growth factor-beta1 and increase the expression of liver-specific genes. A similar phenomenon of the EMT process was observed during the activation of HSCs, which was abrogated by HNF4alpha. Additionally, HNF4alpha deactivated the myofibroblasts through inducing the mesenchymal-to-epithelial transition and inhibited their proliferation.

CONCLUSIONS

Our study suggests that HNF4alpha is critical for hepatic fibrogenesis and upregulation of HNF4alpha might present as an ideal option for the treatment of hepatic fibrosis.

Chemokine-dependent neutrophil recruitment in a murine model of Legionella pneumonia: potential role of neutrophils as immunoregulatory cells

The roles of CXC chemokine-mediated host responses were examined with an A/J mouse model of Legionella pneumophila pneumonia. After intratracheal inoculation of 10(6) CFU of L. pneumophila, the bacterial numbers in the lungs increased 10-fold by day 2; this increase was accompanied by the massive accumulation of neutrophils. Reverse transcription-PCR data demonstrated the up-regulation of CXC chemokines, such as keratinocyte-derived chemokine, macrophage inflammatory protein 2 (MIP-2), and lipopolysaccharide-induced CXC chemokine (LIX). Consistent with these data, increased levels of KC, MIP-2, and LIX proteins were observed in the lungs and peaked at days 1, 2, and 2, respectively. Although the administration of anti-KC or anti-MIP-2 antibody resulted in an approximately 20% decrease in neutrophil recruitment on day 2, no increase in mortality was observed. In contrast, the blockade of CXC chemokine receptor 2 (CXCR2), a receptor for CXC chemokines, including KC and MIP-2, strikingly enhanced mortality; this effect coincided with a 67% decrease in neutrophil recruitment. Interestingly, anti-CXCR2 antibody did not affect bacterial burden by day 2, even in the presence of a lethal challenge of bacteria. Moreover, a significant decrease in interleukin-12 (IL-12) levels, in contrast to the increases in KC, MIP-2, and LIX levels, was demonstrated for CXCR2-blocked mice. These data indicated that CXCR2-mediated neutrophil accumulation may play a crucial role in host defense against L. pneumophila pneumonia in mice. The increase in lethality without a change in early bacterial clearance suggested that neutrophils may exert their protective effect not through direct killing but through more immunomodulatory actions in L. pneumophila pneumonia. We speculate that a decrease in the levels of the protective cytokine IL-12 may explain, at least in part, the high mortality in the setting of reduced neutrophil recruitment.

Segmentation and measurement of the cortex from 3-D MR images using coupled-surfaces propagation

The cortex is the outermost thin layer of gray matter in the brain; geometric measurement of the cortex helps in understanding brain anatomy and function. In the quantitative analysis of the cortex from MR images, extracting the structure and obtaining a representation for various measurements are key steps. While manual segmentation is tedious and labor intensive, automatic reliable efficient segmentation and measurement of the cortex remain challenging problems, due to its convoluted nature. Here we present a new approach of coupled-surfaces propagation, using level set methods to address such problems. Our method is motivated by the nearly constant thickness of the cortical mantle and takes this tight coupling as an important constraint. By evolving two embedded surfaces simultaneously, each driven by its own image-derived information while maintaining the coupling, a final representation of the cortical bounding surfaces and an automatic segmentation of the cortex are achieved. Characteristics of the cortex, such as cortical surface area, surface curvature, and cortical thickness, are then evaluated. The level set implementation of surface propagation offers the advantage of easy initialization, computational efficiency, and the ability to capture deep sulcal folds. Results and validation from various experiments on both simulated and real three-dimensional (3-D) MR images are provided.

Slk19p is a centromere protein that functions to stabilize mitotic spindles

We have identified a novel centromere-associated gene product from Saccharomyces cerevisiae that plays a role in spindle assembly and stability. Strains with a deletion of SLK19 (synthetic lethal Kar3p gene) exhibit abnormally short mitotic spindles, increased numbers of astral microtubules, and require the presence of the kinesin motor Kar3p for viability. When cells are deprived of both Slk19p and Kar3p, rapid spindle breakdown and mitotic arrest is observed. A functional fusion of Slk19p to green fluorescent protein (GFP) localizes to kinetochores and, during anaphase, to the spindle midzone, whereas Kar3p-GFP was found at the nuclear side of the spindle pole body. Thus, these proteins seem to play overlapping roles in stabilizing spindle structure while acting from opposite ends of the microtubules.

Transplantation of umbilical cord mesenchymal stem cells alleviates lupus nephritis in MRL/lpr mice

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease, which, despite the advances in immunosuppressive medical therapies, remains potentially fatal in some patients, especially in treatment-refractory patients. This study found that transplantation of umbilical cord mesenchymal stem cells (UC-MSCs) has the same therapeutic effect as transplantation of bone marrow mesenchymal stem cells (BM-MSCs), which has been reported to be efficient in treating SLE-related symptoms in MRL/lpr mice. Multi-treatment (at the 18th, 19th, and 20th weeks of age) of 1 × 10(6) UC-MSCs was able to decrease the levels of 24-h proteinuria, serum creatinine, and anti-double-stranded DNA (dsDNA) antibody, and the extent of renal injury such as crescent formation in MRL/lpr mice. A lower, but still significant, reduction in these parameters was also observed in mice receiving a single dose of UC-MSCs (at the 18th week). UC-MSCs treatment also inhibited expression of monocyte chemotactic protein-1 (MCP-1) and high-mobility group box 1 (HMGB-1) expression in a similar fashion. UC-MSCs labeled with carboxyfluorescein diacetate succinimidyl ester (CFSE) were found in the lungs and kidneys 1 week post infusion. In addition, after 11 weeks post UC-MSCs infusion, human cells were found in kidney of UC-MSCs-treated mice. These findings indicated that UC-MSCs transplantation might be a potentially promising approach in the treatment of lupus nephritis, possibly by inhibiting MCP-1 and HMGB-1 production.

Mice deficient in the candidate tumor suppressor gene Hic1 exhibit developmental defects of structures affected in the Miller-Dieker syndrome

HIC1 is a candidate tumor suppressor gene which is frequently hypermethylated in human tumors, and its location within the Miller-Dieker syndrome's critical deletion region at chromosome 17p13.3 makes it a candidate gene for involvement in this gene deletion syndrome. To study the function of murine Hic1 in development, we have created Hic1 -deficient mice. These animals die perinatally and exhibit varying combinations of gross developmental defects throughout the second half of development, including acrania, exencephaly, cleft palate, limb abnormalities and omphalocele. These findings demonstrate a role for Hic1 in the development of structures affected in the Miller-Dieker syndrome, and provide functional evidence to strengthen its candidacy as a gene involved in this disorder.

Chinese SLE Treatment and Research group (CSTAR) registry: I. Major clinical characteristics of Chinese patients with systemic lupus erythematosus

The Chinese systemic lupus erythematosus (SLE) treatment and research group (CSTAR) provides major clinical characteristics of SLE in China and establishes a platform to provide resources for future basic and clinical studies. CSTAR originated as a multicentre, consecutive, and prospective design. The data were collected online from 104 rheumatology centers, which covered 30 provinces in China. The registered patients were required to meet four or more of the American College of Rheumatology (ACR) criteria for the classification of SLE. All CSTAR centers use the same protocol-directed methods to provide uniform evaluations, which included demographic data, clinical features, laboratory examinations, and disease activity evaluations. The patient samples, including DNA samples and sera, were also collected for further quality controls and additional studies. Preliminary analysis from 2104 baseline evaluations was available for this analysis. Of 1914 female and 190 male patients (F:M=10.1), the mean age at onset was 29.2 y with confirmed diagnosis one year later at the age of 30.3 y. Eighty four (4.2%) of 2002 patients had a family history of rheumatic diseases, including 34 (1.7%) cases with SLE. In addition, one hundred and seven (5.2%) abnormal pregnancies were recorded among 2026 experiences. The characteristics of the CSTAR cohort were compared to similarly sized cohorts from other studies. We found that 56.1% of patients presented with concurrent hematological disorders compared to only 18.2% of European patients. Moreover, 47.4% of patients presented with nephropathy compared to 27.9% of European patients. Conversely, neurological manifestations were only seen in 4.8% of Chinese SLE patients compared to 19.4% of European patients, 12.1% of U.S. patients, 22.8% of Malaysian patients and 26.4% of Latin Americans. Pulmonary arterial hypertension and interstitial lung diseases were complications identified in 3.8% and 4.2% of Chinese lupus patients, respectively. The CSTAR registry has provided epidemiological data and phenotypes of Chinese patients with SLE, and has demonstrated several differences between ethnicities. Clinical data and biologic samples would be valuable resources for future translational studies with national and international collaboration.

Triphalangeal thumb-polysyndactyly syndrome and syndactyly type IV are caused by genomic duplications involving the long range, limb-specific SHH enhancer

BACKGROUND

The Sonic hedgehog (SHH) protein produced in the zone of polarising activity (ZPA) is a major determinant of the identity and numbers of digits in early limb development. Preaxial polydactyly types II (PPD2) and III (PPD3) have been mapped to a critical region at 7q36, and subsequently shown to be caused by point mutations in the ZPA regulatory sequence (ZRS), a long range cis-regulator for the SHH gene. Triphalangeal thumb-polysyndactyly syndrome (TPTPS) and syndactyly type IV (SD4) were also mapped to the 7q36 region but pathogenic mutations in ZRS have not yet been affirmed.

METHODS AND RESULTS

We performed linkage and haplotype analysis in six Han Chinese families with TPTPS and/or SD4, and refined the disease locus to an interval of 646 kb containing ZRS. In all families, the affected individuals heterozygous at rs10254391 (a single nucleotide polymorphism within ZRS) revealed a remarkable allele imbalance on sequence chromatogram. Using real-time quantitative polymerase chain reaction (qPCR), we identified duplication of ZRS and found that this duplication segregated with the limb phenotypes in all families but was not detected in unaffected family members or in unrelated control individuals. The duplication was also confirmed by interphase fluorescence in situ hybridisation (FISH) in an affected individual. We designed 17 additional qPCR assays and defined the minimum duplications in all six families, ranging from 131kb to 398kb.

CONCLUSION

Both TPTPS and SD4 are due to duplications involving ZRS, the limb specific SHH enhancer. Point mutations in the ZRS and duplications encompassing the ZRS cause distinctive limb phenotypes.

The association of squamous cell carcinomas of the nasopharynx with Epstein-Barr virus shows geographical variation reminiscent of Burkitt's lymphoma

Nasopharyngeal carcinoma (NPC) is rare in most parts of the world but occurs with high incidence in certain regions, such as South-East Asia. Two major histological types of NPC are recognized, non-keratinizing carcinoma and squamous cell carcinoma. Non-keratinizing NPCs, which include undifferentiated NPC, are invariably associated with Epstein-Barr virus (EBV) infection, regardless of the geographical or ethnic origin of the patients. By contrast, conflicting results have been published concerning a possible association of squamous cell NPC with the virus. To address this question, squamous cell NPCs have been collated from an area where NPC is endemic, Hong Kong, and from two regions where NPC occurs with a lower incidence, Chengdu, PR China, and Birmingham, United Kingdom. In situ hybridization for the detection of the small EBV-encoded nuclear RNAs (EBERs) demonstrated that all 22 cases from Hong Kong were EBV-positive. By contrast, EBV was detectable in 7 of 19 cases from central China, and in 3 of 7 cases from the U.K. Expression of the virus-encoded latent membrane protein 1 (LMP1) was detected in 3 of 32 EBV-positive squamous cell NPCs. These results indicate that the association of squamous cell NPCs with EBV shows geographical variability in a manner which is reminiscent of the situation encountered in Burkitt's lymphoma. This suggests that squamous cell NPCs are a pathogenetically heterogeneous group of tumours distinct from non-keratinizing NPCs.

Antitumor activity and pharmacokinetics of a mixed-backbone antisense oligonucleotide targeted to the RIalpha subunit of protein kinase A after oral administration

Overexpression of the RIalpha subunit of cAMP-dependent protein kinase (PKA) has been demonstrated in various human cancers. PKA has been suggested as a potential target for cancer therapy. The goal of the present study was to evaluate an anti-PKA antisense oligonucleotide (mixed-backbone oligonucleotide) as a therapeutic approach to human cancer treatment. The identified oligonucleotide inhibited the growth of cell lines of human colon cancer (LS174T, DLD-1), leukemia (HL-60), breast cancer (MCF-7, MDA-MB-468), and lung cancer (A549) in a time-, concentration-, and sequence-dependent manner. In a dose-dependent manner, the oligonucleotide displayed in vivo antitumor activity in severe combined immunodeficient and nude mice bearing xenografts of human cancers of the colon (LS174T), breast (MDA-MB-468), and lung (A549). The routes of drug administration were intraperitoneal and oral. Synergistic effects were found when the antisense oligonucleotide was used in combination with the cancer chemotherapeutic agent cisplatin. The pharmacokinetics of the oligonucleotide after oral administration of (35)S-labeled oligonucleotide into tumor-bearing mice indicated an accumulation and retention of the oligonucleotide in tumor tissue. This study further provides a basis for clinical studies of the antisense oligonucleotide targeted to the RIalpha subunit of PKA (GEM 231) as a cancer therapeutic agent used alone or in combination with conventional chemotherapy.

Cephalometric comparisons between Chinese and Caucasian patients with obstructive sleep apnea

The purpose of this study was to compare two groups of adult men from different ethnic backgrounds and with obstructive sleep apnea; they were selected by matching age, gender, skeletal pattern, body mass index, and respiratory disturbance index. Pretreatment cephalometric radiographs and overnight polysomnograms of 30 Chinese and 43 Caucasian patients with Class II, Division 1 malocclusions were analyzed to investigate if there were craniofacial and upper airway structural differences between the two ethnic groups. The Chinese group, when compared with the group of Caucasian patients, revealed more severe underlying craniofacial skeletal discrepancies with significantly smaller maxilla and mandibles, more severe mandibular retrognathism, proclined lower incisors, increased total and upper facial heights, and steeper and shorter anterior cranial bases. However, no significant differences were found between the two groups in posterior facial height, ratio of upper to lower anterior facial height, and the position of hyoid bone, maxilla, and upper incisors. With regard to soft tissue and upper airway measurements, there were no significant ethnic differences in tongue and soft palate size, vertical length of oropharynx, and anteroposterior dimensions of the upper airway at most of the levels except for a larger super-posterior airway space, a larger nasopharynx and oropharynx cross-sectional area, and a smaller tongue height in the Chinese group. We conclude that there are a number of craniofacial and upper airway structures that differ between the two ethnic groups that may be relevant to the treatment of obstructive sleep apnea in various ethnic groups.