An altered antioxidant balance occurs in Down syndrome fetal organs: Implications for the “gene dosage effect” hypothesis

Down syndrome (DS) is the congenital birth defect responsible for the greatest number of individuals with mental retardation. It arises due to trisomy of human chromosome 21 (HSA21) or part thereof. To date there have been limited studies of HSA21 gene expression in trisomy 21 conceptuses. In this study we investigate the expression of the HSA21 antioxidant gene, Cu/Zn-superoxide dismutase-1 (SOD1) in various organs of control and DS aborted conceptuses. We show that SOD1 mRNA levels are elevated in DS brain, lung, heart and thymus. DS livers show decreased SOD1 mRNA expression compared with controls. Since non-HSA21 antioxidant genes are reported to be concomitantly upregulated in certain DS tissues, we examined the expression of glutathione peroxidase-1 (GPX1) in control and DS fetal organs. Interestingly, GPX1 expression was unchanged in the majority of DS organs and decreased in DS livers. We examined the SOD1 to GPX1 mRNA ratio in individual organs, as both enzymes form part of the body's defense against oxidative stress, and because a disproportionate increase of SOD1 to GPX1 results in noxious hydroxyl radical damage. All organs investigated show an approximately 2-fold increase in the SOD1 to GPX1 mRNA ratio. We propose that it is the altered antioxidant ratio that contributes to certain aspects of the DS phenotype.

Impact of treatment on the outcome of acute myeloid leukemia with inversion 16: a single institution's experience

To identify treatment factors that may affect the survival of children with inv(16)(p13.1q22), we compared the outcomes of 19 patients with this genetic feature treated at our institution during two treatment eras. Nine patients were treated during era 1 (1980 to 1987), and 10 were treated during era 2 (1988 to 1996). All entered complete remission (CR) with induction therapy. Eight of the nine children treated in era 1 died, seven of relapsed leukemia. In contrast, three of 10 patients treated during era 2 have died, all of non-disease-related causes. Event-free survival (EFS) estimates were significantly higher for patients treated during era 2 than for those treated during era 1 (P = 0.03); the 6-year estimates were 70 +/- 15% (s.e.) and 11 +/- 7%, respectively. Era 2 treatment protocols differed from those of era 1 in their use of higher doses of cytarabine and etoposide during induction and consolidation chemotherapy and in their use of 2-chlorodeoxyadenosine (2-CDA). These results suggest that dose intensification of cytarabine benefits children with AML and inv(16), as is the case in adults. They also suggest that dose intensification of etoposide and addition of 2-CDA may also offer an advantage. This study underscores the dependence of the prognostic impact of cytogenetic features on the efficacy of treatment.

From single site to societal belief: the impact of pediatric oncology nursing research

This review describes the evolution of pediatric oncology nursing research over the past 25 years. It highlights practice-changing contributions from single-site studies and from multisite trials and discusses strategies for interdisciplinary collaboration. Technological advances that will alter the way in which studies are conducted and findings are disseminated will influence the future of nursing research. Studies implemented by pediatric nurse researchers will continue to influence practice and change how we, and others, view the experience of childhood cancer.

Preoxygenation for tracheal suctioning in intubated, ventilated newborn infants

BACKGROUND

Endotracheal suctioning for mechanically ventilated infants is routine practice in neonatal intensive care. However, this practice is associated with serious complications including lobar collapse, pneumothorax, bradycardia and hypoxemia. Increasing the inspired oxygen immediately prior to suction (preoxygenation) has been proposed as an intervention to minimise the risk of complications.

OBJECTIVES

To compare the effects of preoxygenation with no preoxygenation for endotracheal suctioning on ventilated newborn infants. To conduct sub group analyses by i) different populations of newborn infants; by gestational age <30 weeks, <34 weeks and <37 weeks and by disease; infants with chronic lung disease compared to those without and; ii) by different techniques of endotracheal suctioning; with or without disconnection from the ventilator, increased mechanical ventilation, use of manual ventilation and chest wall vibrations or percussion.

SEARCH STRATEGY

The standard search strategy of the Neonatal Review Group was used. This included searches of electronic databases; Oxford Database of Perinatal Trials; Cochrane Controlled Trials Register (Cochrane Library Issue 1 2001); MEDLINE (1966 - April 2001); and CINAHL (1982-2001) using MeSH term infant-newborn and text terms oxygen* and suction*, preoxygenation, pre-oxygenation and premature and also previous reviews including cross references, abstracts in conferences and symposia proceedings, expert informants, journal hand searching in the English language.

SELECTION CRITERIA

Random or quasi random controlled trials of mechanically ventilated neonates in which endotracheal suctioning with preoxygenation was compared to suctioning without preoxygenation.

DATA COLLECTION AND ANALYSIS

Standard methods of the Cochrane Collaboration and its Neonatal Review Group were used, including independent assessment of trial quality and extraction of data by the authors. Data were analysed using relative risk (RR) for dichotomous outcomes and mean difference (MD) for data measured on a continuous scale with the use of 95% confidence intervals. Meta-analysis was conducted using a fixed effects model.

MAIN RESULTS

One cross-over trial involving outcomes for 16 preterm neonates was included in this review. Preoxygenation, prior to an endotracheal suctioning procedure involving two suctions, resulted in a statistically significant reduction in infants with hypoxemia (TcPO2 <40 mmHg) at the end of the first suction (RR 0.18, 95% CI 0.05, 0.69), at the end of the second suction (RR 0.23, 95% CI 0.08, 0.66) and also at 120 seconds after the second suction (RR 0.10, 95% CI 0.01, 0.69). Mean TcPO2 was statistically significantly higher in the preoxygenation group at the end of the first suction (MD 25.00 mmHg, 95%CI 14.20, 35.80), second suction (MD 24.80, 95% CI 14.80, 34.80) and also at 120 seconds after the second suction (MD 29.10, 95% CI 14.96, 43.24). The time taken to return to baseline oxygenation status was shorter than the group not receiving preoxygenation (MD -2.12 minutes, 95% CI -3.82, -0.42).

REVIEWER'S CONCLUSIONS

No recommendations for practice can be confidently made from the results of this review. Although preoxygenation was shown to decrease hypoxemia at the time of suctioning, other clinically important short and longer-term outcomes including adverse effects were unable to be assessed. Further studies are needed to adequately assess the effects of this widely practiced procedure.

The mouse brain transcriptome by SAGE: differences in gene expression between P30 brains of the partial trisomy 16 mouse model of Down syndrome (Ts65Dn) and normals

Trisomy 21, or Down syndrome (DS), is the most common genetic cause of mental retardation. Changes in the neuropathology, neurochemistry, neurophysiology, and neuropharmacology of DS patients' brains indicate that there is probably abnormal development and maintenance of central nervous system structure and function. The segmental trisomy mouse (Ts65Dn) is a model of DS that shows analogous neurobehavioral defects. We have studied the global gene expression profiles of normal and Ts65Dn male and normal female mice brains (P30) using the serial analysis of gene expression (SAGE) technique. From the combined sample we collected a total of 152,791 RNA tags and observed 45,856 unique tags in the mouse brain transcriptome. There are 14 ribosomal protein genes (nine under expressed) among the 330 statistically significant differences between normal male and Ts65Dn male brains, which possibly implies abnormal ribosomal biogenesis in the development and maintenance of DS phenotypes. This study contributes to the establishment of a mouse brain transcriptome and provides the first overall analysis of the differences in gene expression in aneuploid versus normal mammalian brain cells.

Improving antenatal recognition of women at risk for postnatal depression

The purpose of this study was to assess the effectiveness of a practical antenatal screen used at the Royal Women's Hospital, Brisbane, to identify women at risk for postnatal depression. It was a prospective, hospital-based, cohort study of 901 women (600 with and 301 without prenatal risk factors for postnatal depression). Depression was measured 16 weeks after the birth using the Edinburgh Postnatal Depression Scale. More of the women with a prenatal risk factor for depression (25.9%) scored above 12 on the Edinburgh Postnatal Depression Scale than those without any risk (10.9%) (p < or = 0.001). Low social support (p < or = 0.001), a personal history of mood disorder (p < or = 0.001) and a past history of postnatal depression ( p = 0.002) were all strongly associated with postnatal depression in this sample. Results indicate that an objective, psychosocial assessment during pregnancy improves recognition of women at risk for postnatal depression.

Childhood carcinoid tumors: the St Jude Children's Research Hospital experience

BACKGROUND/PURPOSE

To better characterize childhood carcinoid tumors, the authors reviewed the clinical presentation, treatment, and outcomes of pediatric patients with these rare tumors.

METHODS

A retrospective review was conducted of medical records and pathologic materials of all children with carcinoid tumors treated at St Jude Children's Research Hospital between December 1977 and March 1999.

RESULTS

Eight patients (median age, 12.7 years) were identified; 2 were boys, and 7 were white. Primary tumor sites were the appendix (n = 5), small intestine (n = 1), bronchus (n = 1), and 1 unknown site. In 7 cases, carcinoid tumor was not suspected at the time the tumor was identified. Seven patients had localized disease; 5 remain disease-free after complete resection, and 2, whose carcinoid tumors were identified incidentally, died of metastatic mucinous adenocarcinoma of the colon. One patient who presented with symptoms of carcinoid syndrome had metastatic disease that responded poorly to cytotoxic chemotherapy and remains alive with active disease.

CONCLUSIONS

Although most pediatric carcinoid tumors arise in the appendix, these tumors also occur in other primary sites. Clinical awareness and early diagnosis are important factors in preventing morbidity and mortality. Outcomes are excellent for patients with localized disease that is completely resected, but those with metastatic disease fare poorly. New therapeutic strategies are needed for these patients.

Simultaneous separation and quantitation of the major bovine whey proteins including proteose peptone and caseinomacropeptide by reversed-phase high-performance liquid chromatography on polystyrene-divinylbenzene

A precise, sensitive and reliable RP-HPLC method was developed to enable not only unequivocal determination of alpha-lactalbumin and beta-lactoglobulin in bovine whey samples, but also simultaneous measurement of proteose peptone, caseinomacropeptide, bovine serum albumin and immunoglobulin G. The optimised method on the Resource RPC column allowed separation of the proteins in 30 min and could be applied to the analysis of soluble proteins in a variety of commercial and laboratory whey products. Furthermore, some qualitative information on protein heterogeneity and quality could be derived from the RP-HPLC analyses with additional data available from on-line electrospray mass spectrometry. Within- and between-day repeatability over a wide range of concentrations was excellent (RSD< or =5%) for all proteins except immunoglobulin G and bovine serum albumin where RSD was 7-10%. Analysis of grouped data from whey protein concentrate and whey protein isolate samples gave a limit of detection of < or =0.3% powder mass and a limit of quantitation of < or =1.0% powder mass for all proteins except immunoglobulin G. Limits of detection and quantitation were 0.6% and 2.0%, respectively, for this protein. Quantitative data obtained by the RP-HPLC method compared very favourably with data obtained by alternative methods of whey protein analysis.

Application of Alu-splice PCR on chromosome 21: DSCR1 and Intersectin

Down syndrome (DS) is a major cause of mental retardation and congenital heart defects, with an overall incidence of one in 700 live births. DS is caused by increases in the amounts of a number of normal gene products, the exact number and identity of which are presently unknown. Elucidating the molecular basis of DS relies on the identification of the gene products whose augmentation by 50% or more causes symptoms of the disease. With the aim of contributing to the transcriptional map of human chromosome 21 and to identify new genes with potential involvement in DS, we developed a technique to isolate expressed sequences called Alu-splice PCR, which is very simple to perform and is independent of gene expression patterns. Putative exons are PCR amplified in genomic DNA by virtue of their proximity to Alu repeats using primers designed from splice-site consensus sequences in combination with specific Alu repeat primers. The Alu repeats, which are repetitive DNA elements found exclusively and at high frequency in the genomes of primates, impart the human specificity to the method. The splice-site consensus sequences were used to direct primers to exon boundaries. Using the Alu-splice technique, we have identified at least three new genes. We trapped an exon of DSCR1 (Down Syndrome Candidate Region 1) and two different exons of a gene called human Intersectin (ITSN). Presently, we are working with another novel trapped exon to identify the corresponding gene. The major advantage of Alu-splice PCR is that the technique can be readily established in any laboratory which has the basic facilities for molecular biology because no specialised materials or expertise is required.

Alu-splice cloning of human Intersectin (ITSN), a putative multivalent binding protein expressed in proliferating and differentiating neurons and overexpressed in Down syndrome

By Alu-splice PCR we have trapped two exons and subsequently identified the full length cDNA of a human gene, Intersectin (ITSN), which maps to chromosome 21q22.1 between markers D21S320 and D21S325. The gene has the potential to code for at least two different protein isoforms by alternative splicing (ITSN-L and ITSN-S). Intersectin exists with a high degree of similarity in flies, frogs and mammals, suggesting a conserved role in higher eukaryotes. Analysis of the expression pattern of human and mouse Intersectin detected mRNAs in all adult and foetal tissues tested, with the longer isoform present in brain. In situ hybridisation studies in the developing mouse brain showed ITSN expression in both proliferating and differentiating neurons. The genomic structure of ITSN was determined using the chromosome 21 sequences deposited in the public databases. The protein contains several known motifs which implicate ITSN in clathrin mediated endocytosis and synaptic vesicle recycling. The expression pattern of Intersectin in mouse brain, its presumed function and its overexpression in brains from Down syndrome patients, suggest that Intersectin may contribute in a gene dosage-dependent manner to some of the abnormalities of Down syndrome.

Cancer vaccines with emphasis on a viral oncolysate melanoma vaccine

Biotherapy of malignant diseases has become the fourth treatment modality besides surgery, chemo- and radiotherapy. Whole cell melanoma vaccines with or without BCG and other adjuvants, purified ganglioside and shed antigens, recombinant viruses carrying tumor antigens, dendritic cells pulsed with antigenic peptides etc. are in clinical trials. Efficacious viral oncolysate vaccines induce the host to mount tumor-specific cytotoxic T-cell response and prevention of relapses is supported by clinical trials. The use of "polyvalent" whole cell vaccines vs. purified or genetically engineered single antigen vaccines is justified as i. only very few single tumor antigens are present in all tumors of a given histological type; and ii. antigen modulation occurs in tumors rendering them resistant to immune attack generated by vaccine against a single antigen. Thus polyvalent vaccines immunize against several antigens vs. against a selected antigen.

Human minibrain homologue (MNBH/DYRK1): characterization, alternative splicing, differential tissue expression, and overexpression in Down syndrome

The human homologue (MNBH/DYRK1) of the Drosophila minibrain gene maps to human chromosome 21 within the Down syndrome (DS) critical region and is within the region minimally deleted in chromosome 21-linked microcephaly. As a first step in gaining insight into the role that MNBH may have in human neurogenesis, and as a lead-up to the development of mouse models for MNBH overexpression, we have characterized the gene at the molecular level. We describe here the MNBH full-length transcript, alternative splicing, expression profile, and genomic organization. The full-length cDNA of MNBH is 5. 2 kb and is composed of 17 exons spanning 150 kb, between markers D21S335 and D21S337. Transcripts MNBHa and MNBHb arise from the use of different first exons in the 5'-UTR and are differentially expressed. MNBHa is expressed ubiquitiously in a broad spectrum of tissues and is apparently under the control of a CpG island. MNBHb is expressed only in heart and skeletal muscle and is apparently under the control of a TATA-like box. Four alternative splicing events affecting the C-terminus of the protein yield at least four isoforms of MNBH (MNBH-iso1, MNBH-iso2, MNBH-iso3, and MNBH-iso4). A PEST sequence, potentially involved in the rapid degradation of the protein, is present in all the isoforms. A histidine repeat and a serine/threonine domain are present only in the largest form of the protein (MNBH-iso1). MNBH was overexpressed 1.5-fold in DS brains and Dyrk1 about 2.1-fold in the brains of the Ts65Dn mice. The information provided here should be valuable for MNBH mutation studies and aid in the development of DS animal models.

Treatment of mammalian cells with the endoplasmic reticulum-proliferator compactin strongly induces recombinant and endogenous xenobiotic metabolizing enzymes and 3-hydroxy-3-methylglutaryl-CoA reductase in vitro

Some xenobiotics induce membrane-bound drug metabolizing enzymes (Xme) and a profound proliferation of the endoplasmic reticulum (ER) in vivo. However these effects are much weaker in vitro, possibly due to absence of certain transcription factors. We tested the possibility that ER proliferation can affect the level of ER-resident enzymes even in the absence of transcriptional activation. For this purpose we analysed the effects of compactin, which has been shown to induce ER proliferation in vitro, on recombinant Xme, which were expressed from a constitutive viral promoter. High levels of recombinant UDP-glucuronosyltransferase UGT1A6 were achieved by amplification of the UGT1A6 cDNA using the dihydrofolate reductase cDNA as selectable marker in DHFR- CHO cells. Treatment of the resulting cell lines with lipoprotein-deficient serum in the absence and presence of compactin for 5 days resulted in a 1.3- and 2.3-fold, respectively, increase of the UGT enzyme activity towards 4-methylumbelliferone, paralleled by an induction of immunoreactive UGT1A6 protein. Similarly, treatment with this 3-hydroxy-3-methylglutaryl-CoA reductase inhibitor increased the endogenous P450 reductase activity 2.6-fold, concomitant with an increase of immunodetectable protein. As expected compactin induced the level of 3-hydroxy-3-methylglutaryl-CoA reductase. Increased levels of this protein have been associated with a proliferation of the ER. Compactin treatment of a separate cell line that expressed recombinant human P450 reductase increased this enzyme activity fivefold. Pulse-chase experiments revealed that the induction of the recombinant Xme by compactin was most likely due to decreased protein degradation. Our results show that enzyme systems unrelated to those involved in cholesterol biosynthesis are affected by compounds known to affect membrane biogenesis. Since this effect extends to heterologously expressed enzymes, it also provides an efficient means by which to increase the levels of recombinant ER proteins.

Characterization of mild whole-body hyperthermia protocols using human breast, ovarian, and colon tumors grown in severe combined immunodeficient mice

OBJECTIVE

We have shown that one treatment of fever-like whole body hyperthermia (WBH) on mice bearing human breast tumors results in a tumor growth delay. Our goal was to repeat this study in mice bearing human ovarian or colon tumors. We further evaluated this WBH protocol by performing multiple and interrupted WBH treatments.

METHODS

Human tumors were grown in severe combined immunodeficient (SCID) mice. For WBH, core body temperatures were maintained at 39.8+/-0.2 degrees C for 6-8 hours. Multiple treatments were given 6-7 days apart. Interrupted WBH consisted of three 2-hour heatings, 15 minutes apart. Tumor growth time (TGT) was the number of days to grow 1.5 or 2 times in volume.

RESULTS

For WBH-treated ovarian tumors, TGT was 12+/-1.2d, compared with 5.0+/-0.1d for untreated mice (P < 0.05). For colon tumors with one WBH treatment TGT was 4.4+/-1.1d. Two and three treatments had TGTs of 9+/-2.3d and 8+/-1.6d. For the untreated tumors, TGT was 2+/-0.7d (P < 0.01 for one, two, and three treatments). Histological examination indicated that one and two treatments were associated with cellular damage within the tumors. With a slower growing colon tumor, the TGT was 24+/-3.3d with three WBH treatments, compared with 14+/-1.8d for controls (P < 0.01). The TGT of breast tumors treated with interrupted WBH was not significantly different than the noninterrupted, with TGT of 7.3+/-0.8d and 6.2+/-1.0d, respectively.

CONCLUSIONS

These data illustrate that WBH causes a tumor growth delay in mice bearing human ovarian and colon tumors. This response is enhanced with a second treatment of WBH. Interrupted and noninterrupted WBH give comparable anti-tumor results. We will continue to evaluate WBH in various animal models to optimize its potential for clinical administration and maximize the anti-tumor response.