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Biomedical subjects

E Baker

Publications and source records attributed to E Baker.

At least 37 records · Page 2Linked to original sources

Outcome of staged reconstructive surgery for hypoplastic left heart syndrome following antenatal diagnosis.

BACKGROUND AND AIMS: Staged reconstructive surgery has radically altered the prognosis of hypoplastic left heart syndrome (HLHS). Antenatal diagnosis allows for appropriate counselling, and time to consider treatment options. We report outcome from a centre where most cases are antenatally diagnosed and delivered on site. METHODS: Information was collated on 188 consecutive cases of HLHS between 1995 and 2000, including timing of diagnosis, outcome of pregnancy, and age and outcome at each stage of surgery. At Guy's Hospital, 174 cases were diagnosed antenatally, of whom 50 underwent surgery. Fourteen others (five diagnosed antenatally at other centres, and nine diagnosed postnatally) also underwent surgery. RESULTS: Survival after stage I (the Norwood operation) was 52% (33/64). Postoperative survival after stage II (the hemi-Fontan operation, performed in 29), and stage III (the Fontan operation, performed in 10), was 100%. Two late deaths occurred 3 and 10 months after stage II, giving overall survival of 48% (31/64). At follow up, three children have neurological impairment, and one had poor right ventricular function necessitating cardiac transplantation. CONCLUSIONS: Antenatal diagnosis allows informed decisions about treatment options, and facilitates preoperative care. Mortality following stage I is high, irrespective of timing of diagnosis, but medium term outcome for survivors is good.

Cardiac Surgical Procedures↗

A randomized controlled trial of the effects of multi-sensory stimulation (MSS) for people with dementia.

OBJECTIVES: To investigate short-term effects of Multi-Sensory Stimulation (MSS) on behaviour, mood and cognition of older adults with dementia, the generalization of effects to day hospital and home environments and the endurance of any effects over time. DESIGN: A randomized controlled trial comparing MSS with a credible control of one-to-one activities. METHODS: Fifty patients with diagnoses of moderate to severe dementia were randomized to either MSS or Activity groups. Patients participated in eight 30-minute sessions over a 4-week period. Ratings of behaviour and mood were taken before, during and after sessions to investigate immediate effects. Pre, mid, post-trial, and follow-up assessments were taken to investigate any generalization of effects on cognition, behaviour at the day hospital and behaviour and mood at home and endurance of effects once sessions had ceased. RESULTS: Immediately after MSS and Activity sessions patients talked more spontaneously, related better to others, did more from their own initiative, were less bored/inactive, and were more happy, active or alert. Both groups were more attentive to their environment than before, with a significantly greater improvement from the MSS group. At the day hospital, patients in the Activity group improved on their 'speech skills' (amount of speech; initiation of speech), whereas the MSS group remained unchanged during the trial. The MSS group showed a significant improvement in mood and behaviour at home compared to the Activity group whose behaviour deteriorated. No longer-term benefits were shown; indeed, behaviour declined sharply during the month follow-up period. CONCLUSIONS: Both MSS and Activity sessions appear to be effective and appropriate therapies for people with dementia.

Acoustic Stimulation↗

Gene structure and expression study of the SEDL gene for spondyloepiphyseal dysplasia tarda.

Spondyloepiphyseal dysplasia tarda (SEDL) is an X-linked recessive disorder of endochondral bone formation caused by mutations in the SEDL gene. Here we present the structural analysis and subcellular localization of human SEDL. The SEDL gene is composed of six exons and spans a genomic region of approximately 20 kb in Xp22. It contains four Alu sequences in its 3' UTR and an alternatively spliced MER20 sequence in its 5' UTR (exon 2). Complex alternative splicing was detected for exon 4. Altogether seven SEDL pseudogenes were detected in the human genome: SEDLP1, a transcribed retropseudogene (or retro-xaptonuon) on chromosome 19q13.4 with potential to encode a protein identical to that of the SEDL gene; SEDLP2, another retropseudogene (not transcribed) on chromosome 8; and five truncated pseudogenes, SEDLP3-SEDLP7, on chromosome Yq11.23. Based on the knowledge of the yeast SEDL ortholog we speculated that the SEDL protein may participate along the ER-to-Golgi transport compartments. To test this hypothesis we performed transient transfection studies with tagged recombinant mammalian SEDL proteins in Cos-7 cells. The tagged SEDL proteins localized to perinuclear structures that partly overlapped with the intermediate ER-Golgi compartment (ERGIC; or vesicular tubular complex, VTC). Two human SEDL mutations (157-158delAT and C271T(STOP)) introduced into SEDL FLAG and GFP constructs led to the misplacement of the SEDL protein primarily to the cell nucleus and partially to the cytoplasm. Based on these experiments we suggest that the COOH end of the SEDL protein might be responsible for proper targeting of SEDL along the ER-Golgi membrane compartments (including Golgi and ERGIC/VTC).

Alternative Splicing↗

Common chromosomal fragile site FRA16D sequence: identification of the FOR gene spanning FRA16D and homozygous deletions and translocation breakpoints in cancer cells.

Fluorescence in situ hybridization of a tile path of DNA subclones has previously enabled the cyto-genetic definition of the minimal DNA sequence which spans the FRA16D common chromosomal fragile site, located at 16q23.2. Homozygous deletion of the FRA16D locus has been reported in adenocarcinomas of stomach, colon, lung and ovary. We have sequenced the 270 kb containing the FRA16D fragile site and the minimal homozygously deleted region in tumour cells. This sequence enabled localization of some of the tumour cell breakpoints to regions which contain AT-rich secondary structures similar to those associated with the FRA10B and FRA16B rare fragile sites. The FRA16D DNA sequence also led to the identification of an alternatively spliced gene, named FOR (fragile site FRA16D oxidoreductase), exons of which span both the fragile site and the minimal region of homozygous deletion. In addition, the complete DNA sequence of the FRA16D-containing FOR intron reveals no evidence of additional authentic transcripts. Alternatively spliced FOR transcripts (FOR I, FOR II and FOR III) encode proteins which share N-terminal WW domains and differ at their C-terminus, with FOR III having a truncated oxidoreductase domain. FRA16D-associated deletions selectively affect the FOR gene transcripts. Three out of five previously mapped translocation breakpoints in multiple myeloma are also located within the FOR gene. FOR is therefore the principle genetic target for DNA instability at 16q23.2 and perturbation of FOR function is likely to contribute to the biological consequences of DNA instability at FRA16D in cancer cells.

Alternative Splicing↗

Cloning of the cDNA and localization of the gene encoding human NRBP, a ubiquitously expressed, multidomain putative adapter protein.

Adapter proteins modulate multiple signaling pathways by regulating the aggregation of other factors into signaling complexes. Here we have identified a novel human cDNA encoding NRBP, a multidomain putative adapter protein containing (i) two putative nuclear receptor binding motifs (LXXLL), (ii) a putative binding domain for Src homology-2 (SH2) domain containing proteins, (iii) a kinase-like domain, (iv) a bipartite nuclear localization signal, and (v) three sequences rich in glutamic acid, serine, proline, and threonine (PEST) residues. The NRBP mRNA transcript, of approximately 2.4 kb, was ubiquitously expressed in a wide range of normal human tissues and 15 human tumor cell lines. The NRBP cDNA is predicted to encode a polypeptide of 535 amino acids with a molecular mass of 59.8 kDa. Translation of NRBP mRNA in vitro reveals three translation products of 60, 51, and 43 kDa, suggesting that translation of NRBP may initiate at multiple sites. The NRBP gene was localized to human chromosome 2p23, near the location of the NCOA1 gene encoding the nuclear receptor coactivator, steroid receptor coactivator-1 (SRC-1). The features of NRBP predict a function as an adapter protein potentially linking signaling pathways involving nuclear receptors and SH2 domain containing proteins.

3' Untranslated Regions↗

Persistence of physiological self antigen is required for the regulation of self tolerance.

Endogenous Ag requirement for induction and maintenance of T cell tolerance has been extensively investigated in mice that express a transgenic Ag and/or its cognate transgenic TCR. In contrast, studies on tolerance for physiologically expressed self Ag and normal T cells are limited. Herein, we showed that the murine ovarian-specific ZP3 Ag is detectable from birth. Tolerance to ZP3 is detected in female relative to male mice. In comparison to males, 100-fold more ovarian peptide (pZP3) is required to elicit a comparable pathogenic response in females. Female tolerance to pZP3 was dependent on the presence of endogenous ovarian Ag, because neonatal ovariectomy converted the female response to that of males. Moreover, in female mice that were ovariectomized from the ages of 1-6 wk, the pZP3 responses were enhanced to the male level if ovaries were removed up to 7 days, but not 3 days, before adult challenge with pZP3. Thus, the physiologically expressed ZP3 Ag induces tolerance to pZP3, and the maintenance of tolerance is critically dependent on the continuous presence of the endogenous ovarian Ag. In contrast, exposure to endogenous ovarian Ag confined to the neonatal period is insufficient for the induction and maintenance of tolerance to ZP3.

Age Factors↗

Chromosomal fragile site FRA16D and DNA instability in cancer.

It has been proposed that common aphidicolin-inducible fragile sites, in general, predispose to specific chromosomal breakage associated with deletion, amplification, and/or translocation in certain forms of cancer. Although this appears to be the case for the fragile site FRA3B and may be the case for FRA7G, it is not yet clear whether this association is a general property of this class of fragile site. The major aim of the present study was to determine whether the FRA16D chromosomal fragile site locus has a role to play in predisposing DNA sequences within and adjacent to the fragile site to DNA instability (such as deletion or translocation), which could lead to or be associated with neoplasia. We report the localization of FRA16D within a contig of cloned DNA and demonstrate that this fragile site coincides with a region of homozygous deletion in a gastric adenocarcinoma cell line and is bracketed by translocation breakpoints in multiple myeloma, as reported previously (Chesi, M., et al., Blood, 91: 4457-4463, 1998). Therefore, given similar findings at the FRA3B and FRA7G fragile sites, it is likely that common aphidicolin-inducible fragile sites exhibit the general property of localized DNA instability in cancer cells.

Adenocarcinoma↗

Gender differences in brain volume and size of corpus callosum and amygdala of rhesus monkey measured from MRI images.

While it has been established that the weight of the female rhesus monkey brain is less than that of the male, the sexual dimorphism of specific brain structures has not been well-documented. To further understand potential sex differences, we measured the whole brain volume and the size of the corpus callosum (mid-sagittal) and amygdala (largest coronal section) in MRI images from juvenile to adult male and female rhesus monkeys between 8 months and 7.2 years of age. The mean volume of the male brain was 89.2 +/- 1.9 (S.E.M.) compared to the female brain volume of 70.8 +/- 0.72 cm3. The average area of the corpus callosum increased from 8 months to 4.5 years; 0.56 to 0.93 cm2 in males and 0.45 to 0.66 cm2 in females. However, the average area of splenium is significantly greater in females (0.280 cm2), than males (0.184 cm2). The average area of the amygdala did not change with age; it was 1.07 +/- 0.037 (S.E.M.) in males and 1.08 +/- 0.022 cm2 in females. This data suggests that the whole brain volume and the size of the entire corpus callosum of young adult female rhesus monkeys are approximately 20% smaller than those of young adult males. Interestingly, the area of the splenial portion of the corpus callosum is larger in female monkeys. The size of the amygdala showed no sex difference.

Age Factors↗

Early diagnosis of fetal bladder outlet obstruction.

Prenatal ultrasonography has facilitated early diagnosis of in utero bladder outlet obstruction. This represents one of the earliest diagnoses of prune-belly syndrome and sheds light on the natural history of the bladder outlet obstruction in the fetus.

Adult↗

Superantigens - powerful modifiers of the immune system.

Superantigens are powerful microbial toxins that activate the immune system by binding to class II major histocompatibility complex and T-cell receptor molecules. They cause a number of diseases characterized by fever and shock and are important virulence factors for two human commensal organisms, Staphylococcus aureus and Streptococcus pyogenes, as well as for some viruses. Their mode of action and variation around the common theme of over-stimulating T cells, provides a rich insight into the constant battle between microbes and the immune system.

Animals↗

Analysis of replication timing at the FRA10B and FRA16B fragile site loci.

The molecular basis for the cytogenetic appearance of chromosomal fragile sites is not yet understood. Late replication and further delay of replication at fragile sites expressing alleles has been observed for FRAXA, FRAXE and FRA3B fragile site loci. We analysed the timing of replication at the FRA10B and FRA16B loci to determine whether late replication is a feature which is shared by all fragile sites and, therefore, is a necessary condition for chromosomal fragile site expression. The FRA10B locus was located in a transitional region between early and late zones of replication. Fragile and non-fragile alleles exhibit a similar replication pattern proximal to the repeat but fragile alleles are delayed relative to non-fragile ones on the distal side. Although fragility at FRA10B appears to be caused by expansion of an AT-rich repeat in the region, replication time near the repeat was similar in fragile and non-fragile alleles. The FRA16B locus was late replicating and appeared to replicate even later on fragile chromosomes. While these observations are compatible with the hypothesis that delayed replication may play a role in fragile site expression, they suggest that replication delay may not need to occur at the expanded repeat region itself in order to be permissive for fragility.

Alleles↗

The clinical significance of fragile sites on human chromosomes.

Fragile X syndrome is now a well established common clinical entity and most of those who are aware of the condition probably know that it takes its name from a rare fragile site (FRAXA) on the X chromosome. This is the best known fragile site and its clinical significance is clear. Similar, but a little less known is FRAXE, a fragile site close to that associated with fragile X syndrome, but in this case associated with a mild form of non-specific X-linked mental retardation. These are the only two fragile sites that are unequivocally of clinical significance. A fragile site within the CBL2 oncogene on chromosome 11 has been mapped very close to the deletion breakpoint in a handful of patients with Jacobsen syndrome. It is doubtful that parents with FRA11B are at increased risk of having children with Jacobsen syndrome, but this cannot be ruled out. The common fragile sites have been implicated in oncogenesis since shortly after their discovery in the early 1980s. While a couple of these are within genes that have been implicated in cancer it is unclear whether either the fragile sites, or the genes in which they are located are important in cancer. It may be that the common fragile sites are regions of genomic instability and that this instability is increased in malignant cells, analogous to the enhanced instability seen at microsatellite loci in a number of tumours. Since we all have the common fragile sites there is no suggestion that they give anyone an increased risk of developing malignant disease. In dealing with patients who are found to have fragile sites, other than FRAXA, FRAXE and possibly FRA11B, considerable reassurance can be given that they are not at increased risk of having children with congenital disease or developing disease themselves because of their fragile sites.

Chromosome Aberrations↗

Competency development in public health leadership.

The professional development of public health leaders requires competency-based instruction to increase their ability to address complex and changing demands for critical services. This article reviews the development of the Leadership Competency Framework by the National Public Health Leadership Development Network and discusses its significance. After reviewing pertinent literature and existing practice-based competency frameworks, network members developed the framework through sequential use of workgroup assignments and nominal group process. The framework is being used by network members to develop and refine program competency lists and content; to compare programs; to develop needs assessments, baseline measures, and performance standards; and to evaluate educational outcomes. It is a working document, to be continually refined and evaluated to ensure its continued relevance to performance in practice. Understanding both the applications and the limits of competency frameworks is important in individual, program, and organizational assessment. Benefits of using defined competencies in designing leadership programs include the integrated and sustained development of leadership capacity and the use of technology for increased access and quality control.

Curriculum↗

Characterization of iron uptake from transferrin by murine endothelial cells.

Iron is required by the brain for normal function, however, the mechanisms by which it crosses the blood-brain barrier (BBB) are poorly understood. The uptake and efflux of transferrin (Tf) and Fe by murine brain-derived (bEND3) and lymph node-derived (m1END1) endothelial cell lines was compared. The effects of iron chelators, metabolic inhibitors and the cellular activators, lipopolysaccharide (LPS) and tumour necrosis factor-alpha (TNF-alpha), on Tf and Fe uptake were investigated. Cells were incubated with 59Fe-125I-Tf; Fe uptake was shown to increase linearly over time for both cell lines, while Tf uptake reached a plateau within 2 h. Both Tf and Fe uptake were saturable. bEND3 cells were shown to have half as many Tf receptors as m1END1 cells, but the mean cycling times of a Tf molecule were the same. Tf and Fe efflux from the cells were measured over time, revealing that after 2 h only 25% of the Tf but 80% of the Fe remained associated with the cells. Of 7 iron chelators, only deferriprone (L1) markedly decreased Tf uptake. However, Fe uptake was reduced by more than 50% by L1, pyridoxal isonicotinoyl hydrazone (PIH) and desferrithiocin (DFT). The cellular activators TNF-alpha or LPS had little effect on Tf turnover, but they accelerated Fe uptake in both endothelial cell types. Phenylarsenoxide (PhAsO) and N-ethyl maleimide (NEM), inhibitors of Tf endocytosis, reduced both Tf and Fe uptake in both cell lines, while bafilomycin A1, an inhibitor of endosomal acidification, reduced Fe uptake but did not affect Tf uptake. The results suggest that Tf and Fe uptake by both bEND3 and m1END1 is via receptor-mediated endocytosis with release of Fe from Tf within the cell and recycling of apo-Tf. On the basis of Tf- and Fe-metabolism both cell lines are similar and therefore well suited for use in in vitro models for Fe transport across the BBB.

Animals↗

Gamma-heregulin: a fusion gene of DOC-4 and neuregulin-1 derived from a chromosome translocation.

gamma-Heregulin was identified as an isoform resulting from alternate splicing of the neuregulin-1 gene, after cloning of its cDNA from the MDA-MB-175 breast cancer cell line. gamma-Heregulin was shown to promote growth of cultured MDA-MB-175 cells resulting from activation of its cognate ErbB tyrosine kinase reporters. We show here that gamma-heregulin is transcribed from a fusion gene resulting from a chromosome translocation in MDA-MB-175 cells. The fusion chromosome is described as dic(8:11)(8qter-->8p12::11q13-->11pter). As a result, the 5' end of the gamma-heregulin gene is derived from the stress-induced gene, DOC-4 (11q13), while the 3' end is from the neuregulin-1 gene (8p12). Thus, expression of gamma-heregulin is under the control of the DOC-4 promoter. By contrast with MDA-MB-175 cells, RT-PCR failed to detect a gamma-heregulin transcript in either E9.5 to E13.5 embryonic mouse tissues, adult mouse tissues or other human tumour cell lines. We conclude, therefore, that gamma-heregulin is not a native isoform of the neuregulin-1 gene, but a novel growth factor that may contribute to tumour cell proliferation.

Base Sequence↗