Cardiac tamponade from peripherally-inserted central venous catheters in neonates: Three case reports.

Pericardial effusion (PCE) and cardiac tamponade (CT) are rare but life-threatening complications of percutaneouslyinserted central catheter (PICC) use in neonates. There is often a lack in index of suspicion in a neonate with sudden deterioration, resulting in high mortality. We describe a series of three cases of PICC-related PCE/CT in low birth weight infants whose timely diagnosis with echocardiography and pericardiocentesis led to successful resuscitation and survival. We suggest that echocardiographic skills to determine tip position and pericardiocentesis be taught in neonatal resuscitation programs to ensure good outcomes of this otherwise fatal complication.

Methodological quality assessment of paper-based systematic reviews published in oral health.

OBJECTIVES: This study aimed to conduct a methodological assessment of paper-based systematic reviews (SR) published in oral health using a validated checklist. A secondary objective was to explore temporal trends on methodological quality. MATERIAL AND METHODS: Two electronic databases (OVID Medline and OVID EMBASE) were searched for paper-based SR of interventions published in oral health from inception to October 2014. Manual searches of the reference lists of paper-based SR were also conducted. Methodological quality of included paper-based SR was assessed using an 11-item questionnaire, Assessment of Multiple Systematic Reviews (AMSTAR) checklist. Methodological quality was summarized using the median and inter-quartile range (IQR) of the AMSTAR score over different categories and time periods. RESULTS: A total of 643 paper-based SR were included. The overall median AMSTAR score was 4 (IQR 2-6). The highest median score (5) was found in the pain dentistry and periodontology fields, while the lowest median score (3) was found in implant dentistry, restorative dentistry, oral medicine, and prosthodontics. The number of paper-based SR per year and the median AMSTAR score increased over time (median score in 1990s was 2 (IQR 2-3), 2000s was 4 (IQR 2-5), and 2010 onwards was 5 (IQR 3-6)). CONCLUSION: Although the methodological quality of paper-based SR published in oral health has improved in the last few years, there is still scope for improving quality in most evaluated dental specialties. CLINICAL RELEVANCE: Large-scale assessment of methodological quality of dental SR highlights areas of methodological strengths and weaknesses that can be targeted in future publications to encourage better quality review methodology.

A point mutation in CD28 distinguishes proliferative signals from survival signals.

Upon interaction with its ligand, B7, CD28 becomes phosphorylated on tyrosines. One tyrosine in particular (Y170 in mouse CD28, Y173 in human CD28) has received much attention. This is because it permits CD28 to recruit SH2-containing signaling molecules, including phosphoinositide 3 kinase, Grb2 and Gads. Using mice we employed a transgenic approach to express a tyrosine-->phenylalanine mutant form of CD28 that uncouples these SH2-mediated interactions from CD28. The CD28 mutant is unable to up-regulate expression of the prosurvival protein Bcl-xL, rendering the T cells more susceptible to radiation-induced death. Nonetheless, this mutated form of CD28 still prevents the induction of anergy and promotes T cell proliferation, interleukin 2 secretion and B cell help. Thus, we describe a single point mutation within the CD28 cytoplasmic domain that uncouples signals required for proliferation and survival.

TRAF6 deficiency results in osteopetrosis and defective interleukin-1, CD40, and LPS signaling.

Bone resorption and remodeling is an intricately controlled, physiological process that requires the function of osteoclasts. The processes governing both the differentiation and activation of osteoclasts involve signals induced by osteoprotegerin ligand (OPGL), a member of tumor necrosis factor (TNF) superfamily, and its cognate receptor RANK. The molecular mechanisms of the intracellular signal transduction remain to be elucidated. Here we report that mice deficient in TNF receptor-associated factor 6 (TRAF6) are osteopetrotic with defects in bone remodeling and tooth eruption due to impaired osteoclast function. Using in vitro assays, we demonstrate that TRAF6 is crucial not only in IL-1 and CD40 signaling but also, surprisingly, in LPS signaling. Furthermore, like TRAF2 and TRAF3, TRAF6 is essential for perinatal and postnatal survival. These findings establish unexpectedly diverse and critical roles for TRAF6 in perinatal and postnatal survival, bone metabolism, LPS, and cytokine signaling.

OPGL is a key regulator of osteoclastogenesis, lymphocyte development and lymph-node organogenesis.

The tumour-necrosis-factor-family molecule osteoprotegerin ligand (OPGL; also known as TRANCE, RANKL and ODF) has been identified as a potential osteoclast differentiation factor and regulator of interactions between T cells and dendritic cells in vitro. Mice with a disrupted opgl gene show severe osteopetrosis and a defect in tooth eruption, and completely lack osteoclasts as a result of an inability of osteoblasts to support osteoclastogenesis. Although dendritic cells appear normal, opgl-deficient mice exhibit defects in early differentiation of T and B lymphocytes. Surprisingly, opgl-deficient mice lack all lymph nodes but have normal splenic structure and Peyer's patches. Thus OPGL is a new regulator of lymph-node organogenesis and lymphocyte development and is an essential osteoclast differentiation factor in vivo.

High cancer susceptibility and embryonic lethality associated with mutation of the PTEN tumor suppressor gene in mice.

BACKGROUND: Germ-line and sporadic mutations in the tumor suppressor gene PTEN (also known as MMAC or TEP1), which encodes a dual-specificity phosphatase, cause a variety of cancers such as Cowden disease, glioblastoma, endometrial carcinoma and prostatic cancer. PTEN is widely expressed, and Cowden disease consistently affects various organ systems, suggesting that the PTEN protein must have an important, although as yet poorly understood, function in cellular physiology. RESULTS: Homozygous mutant mice lacking exons 3-5 of the PTEN gene (mPTEN3-5) had severely expanded and abnormally patterned cephalic and caudal regions at day 8.5 of gestation. Embryonic death occurred by day 9.5 and was associated with defective chorio-allantoic development. Heterozygous mPTEN3-5 mice had an increased incidence of tumors, especially T-cell lymphomas; gamma-irradiation reduced the time lapse of tumor formation. DNA analysis of these tumors revealed the deletion of the mPTEN gene due to loss of heterozygosity of the wild-type allele. Tumors associated with loss of heterozygosity in mPTEN showed elevated phosphorylation of protein kinase B (PKB, also known as Akt kinase), thus providing a functional connection between mPTEN and a murine proto-oncogene (c-Akt) involved in the development of lymphomas. CONCLUSIONS: The mPTEN gene is fundamental for embryonic development in mice, as mPTEN3-5 mutant embryos died by day 9.5 of gestation, with patterning defects in cephalic and caudal regions and defective placentation. Heterozygous mice developed lymphomas associated with loss of heterozygosity of the wild-type mPTEN allele, and tumor appearance was accelerated by gamma-irradiation. These lymphomas had high levels of activated Akt/PKB, the protein product of a murine proto-oncogene with anti-apoptotic function, associated with thymic lymphomas. This suggests that tumors associated with mPTEN loss of heterozygosity may arise as a consequence of an acquired survival advantage. We provide direct evidence of the role of mPTEN as a tumor suppressor gene in mice, and establish the mPTEN mutant mouse as an experimental model for investigating the role of PTEN in cancer progression.

Differential requirement for caspase 9 in apoptotic pathways in vivo.

Mutation of Caspase 9 (Casp9) results in embryonic lethality and defective brain development associated with decreased apoptosis. Casp9-/- embryonic stem cells and embryonic fibroblasts are resistant to several apoptotic stimuli, including UV and gamma irradiation. Casp9-/- thymocytes are also resistant to dexamethasone- and gamma irradiation-induced apoptosis, but are surprisingly sensitive to apoptosis induced by UV irradiation or anti-CD95. Resistance to apoptosis is accompanied by retention of the mitochondrial membrane potential in mutant cells. In addition, cytochrome c is translocated to the cytosol of Casp9-/- ES cells upon UV stimulation, suggesting that Casp9 acts downstream of cytochrome c. Caspase processing is inhibited in Casp9-/- ES cells but not in thymocytes or splenocytes. Comparison of the requirement for Casp9 and Casp3 in different apoptotic settings indicates the existence of at least four different apoptotic pathways in mammalian cells.

Essential contribution of caspase 3/CPP32 to apoptosis and its associated nuclear changes.

Caspases are fundamental components of the mammalian apoptotic machinery, but the precise contribution of individual caspases is controversial. CPP32 (caspase 3) is a prototypical caspase that becomes activated during apoptosis. In this study, we took a comprehensive approach to examining the role of CPP32 in apoptosis using mice, embryonic stem (ES) cells, and mouse embryonic fibroblasts (MEFs) deficient for CPP32. CPP32(ex3-/-) mice have reduced viability and, consistent with an earlier report, display defective neuronal apoptosis and neurological defects. Inactivation of CPP32 dramatically reduces apoptosis in diverse settings, including activation-induced cell death (AICD) of peripheral T cells, as well as chemotherapy-induced apoptosis of oncogenically transformed CPP32(-/-) MEFs. As well, the requirement for CPP32 can be remarkably stimulus-dependent: In ES cells, CPP32 is necessary for efficient apoptosis following UV- but not gamma-irradiation. Conversely, the same stimulus can show a tissue-specific dependence on CPP32: Hence, TNFalpha treatment induces normal levels of apoptosis in CPP32 deficient thymocytes, but defective apoptosis in oncogenically transformed MEFs. Finally, in some settings, CPP32 is required for certain apoptotic events but not others: Select CPP32(ex3-/-) cell types undergoing cell death are incapable of chromatin condensation and DNA degradation, but display other hallmarks of apoptosis. Together, these results indicate that CPP32 is an essential component in apoptotic events that is remarkably system- and stimulus-dependent. Consequently, drugs that inhibit CPP32 may preferentially disrupt specific forms of cell death.

FADD: essential for embryo development and signaling from some, but not all, inducers of apoptosis.

FADD (also known as Mort-1) is a signal transducer downstream of cell death receptor CD95 (also called Fas). CD95, tumor necrosis factor receptor type 1 (TNFR-1), and death receptor 3 (DR3) did not induce apoptosis in FADD-deficient embryonic fibroblasts, whereas DR4, oncogenes E1A and c-myc, and chemotherapeutic agent adriamycin did. Mice with a deletion in the FADD gene did not survive beyond day 11.5 of embryogenesis; these mice showed signs of cardiac failure and abdominal hemorrhage. Chimeric embryos showing a high contribution of FADD null mutant cells to the heart reproduce the phenotype of FADD-deficient mutants. Thus, not only death receptors, but also receptors that couple to developmental programs, may use FADD for signaling.

Human CD4 and human major histocompatibility complex class II (DQ6) transgenic mice: supersensitivity to superantigen-induced septic shock.

Rodents are significantly less sensitive to enterotoxin-induced shock, and are thus not valid human disease models. Here, we describe a mouse strain carrying the human CD4 and human major histocompatibility complex (MHC) class II (DQ6) transgenes in an endogenous CD4- and CD8-deficient background. T lymphocytes from these animals react to minute amounts (10-100 times less than control mice) of staphylococcal enterotoxin B (SEB) in vitro, similar to concentrations to which human cells react. In vivo, these double-transgenic, double-knockout mice succumb to normally sublethal amounts of SEB. This sensitivity is not due to a biased T cell receptor V beta repertoire, increased T cell reactivity, or increased sensitivity to macrophage-derived cytokines. Rather, tumor necrosis factor (TNF)-alpha production by T cells and serum levels of TNF-alpha correlate precisely with the clinical syndrome, showing a biphasic T cell-dependent response. These data show that both human CD4 and MHC class II molecules can render mice supersensitive to superantigen-induced septic shock syndrome. This animal model mimics the progression of septic shock in man by transforming normally resistant mice into hypersensitive SEB responders, a trait that is characteristic of humans. Mice that have been humanized by exchanging autochthonous superantigen ligands by their human equivalents may be useful to decipher superantigen responses in vivo and to assess the pathogenesis of superantigen-associated diseases.

The Fps/Fes protein-tyrosine kinase promotes angiogenesis in transgenic mice.

The fps/fes proto-oncogene encodes a cytoplasmic protein-tyrosine kinase known to be highly expressed in hematopoietic cells. To investigate fps/fes biological function, an activating mutation was introduced into the human fps/fes gene which directs amino-terminal myristylation of the Fps/Fes protein. This mutant, myristylated protein induced transformation of Rat-2 fibroblasts. The mutant fps/fes allele was incorporated into the mouse germ line and was found to be appropriately expressed in transgenic mice, in a tissue-specific pattern indistinguishable from that of the endogenous mouse gene. These mice displayed widespread hypervascularity, progressing to multifocal hemangiomas. High levels of both the transgenic human and endogenous murine fps/fes transcripts were detected in vascular tumors by using RNase protection, and fps/fes transcripts were localized to endothelial cells of both the vascular tumors and normal blood vessels by in situ RNA hybridization. Primary human umbilical vein endothelial cultures were also shown to express fps/fes transcripts and the Fps/Fes tyrosine kinase. These results indicate that fps/fes expression is intrinsic to cells of the vascular endothelial lineage and suggest a direct role of the Fps/Fes protein-tyrosine kinase in the regulation of angiogenesis.

Cone cells fail to develop normally in transgenic mice showing ablation of rod photoreceptor cells.

Transgenic mice were derived containing the cytotoxic dt-alpha gene driven by opsin promoter sequences. Mice expressing this construct showed progressive degeneration of rod photoreceptor cells commencing at birth, with obvious depletion of such cells by postnatal day 7. Ablation of rod photoreceptor cells in the transgenic retina was accompanied by the failure of developing cone cells to elaborate outer segments, although all other aspects of cone cell cytodifferentiation appeared normal. The results suggest that the 1.0-kb opsin promoter segment contains rod cell type specificity and that cone cells require maturation of rod cells to complete the late stages of their terminal differentiation and for their maintenance and cellular integrity.

Progressive and regressive fate of lens tumors correlates with subtle differences in transgene expression in gamma F-crystallin-SV40 T antigen transgenic mice.

Regulatory elements of the mouse gamma F-crystallin gene were used to derive transgenic mice expressing SV40 large T antigen in terminally differentiating fiber cells of the ocular lens. The resulting gamma F-crystallin-T antigen mice developed either malignant or regressive lens tumors in a strain-dependent fashion. Developmental and RNA analyses revealed that in both 'tumor-progressing' and 'tumor-regressing' mouse strains expression of the transgene blocked morphological differentiation of lens fibers without appreciably affecting gamma-crystallin gene expression, a marker of terminal lens fiber cell differentiation. Strain-dependent differences in tumorigenic outcome could be correlated with both subtle differences in transgene expression and the ability of tumor cells to escape from the normal confines of the lens. The results implicate the importance of cellular environment to malignant tumor development and provide insight into those features of normal lens ontogeny that may render the lens refractory to the development of spontaneous tumors.

Two enhancer regions in the mouse En-2 locus direct expression to the mid/hindbrain region and mandibular myoblasts.

An En-2/lacZ gene fusion containing 9.5 kb of En-2 genomic DNA was capable of directing lacZ expression in an En-2-specific manner both temporally and spatially during embryogenesis and in the adult. lacZ expression was confined in the embryo to cells within the mid/hindbrain and mandibular arch regions and in the adult to cells of the molecular and granular layers of the cerebellum, and within the pons and colliculi regions. Interestingly, in the adult, transgene expression patterns within the cerebellum in two lines appeared to mark distinct anterior-posterior compartments. Analysis of the expression pattern of this transgene, in fetal and adult mice lacking a functional En-2 protein, provided evidence that the En-2 gene in mouse is not autoregulated. Deletion analysis of the En-2 genomic region and the use of a heterologous promoter identified two enhancer-containing regions of 1.5 and 1.0 kb in length, 5' of the transcribed sequences, which independently directed expression in the embryo to either the mid/hindbrain region or mandibular myoblasts, respectively. The 1.5 kb fragment contains the most anterior neural enhancer and the 1.0 kb fragment, the earliest myogenic enhancer thus far characterized. These En-2-specific regulatory regions can now be used in a biochemical analysis to identify proteins important in anterior-posterior patterning of the vertebrate CNS and in the specification of muscle identity as well as in a mutational analysis to direct expression of other developmentally important genes to these regions.

Expression of S-antigen in retina, pineal gland, lens, and brain is directed by 5'-flanking sequences.

S-antigen (S-Ag) is an abundant protein of the retina and pineal gland that elicits experimental autoimmune uveitis and pinealocytis in several animal species. To study the elements regulating the expression of S-Ag, we generated transgenic mice expressing the chloramphenicol acetyl transferase (CAT) gene under the control of a 1.3-kilobase pair 5'-flanking segment of the mouse S-Ag gene. While all of the transgenic mice expressed CAT activity in the retina, in some animals CAT activity was also detected in the pineal gland, lens, and brain. Immunoblotting, polymerase chain reaction-mediated detection of RNA, and immunocyto-staining of transgenic tissues with antibodies to CAT and S-Ag established that the profile of expression of the transgene corresponded to that of S-Ag; both proteins were detectable in retinal photoreceptor cells, pinealocytes, lens fiber and epithelial cells, the cerebellum, and the cerebral cortex. These results indicate that S-Ag is expressed in a wider spectrum of the cell types than previously recognized and that a 1.3-kilobase pair S-Ag promoter segment contains sufficient information to direct appropriate tissue-specific gene expression in transgenic mice.