Three cases of congenital adrenal hypoplasia with novel mutations in the (NROB1) DAX-1 gene

Abnormalities in the DAX-1 gene (dosage-sensitive sex reversal-adrenal hypoplasia gene on the X chromosome) are a well-recognized cause of congenital adrenal hypoplasia. DAX-1 is expressed in the adrenal cortex, gonads, hypothalamus and anterior pituitary, which gives rise to the clinical features of this deletion. Presentations are varied but salt-wasting and/or hypoglycaemia are the most common in an infant, with late onset of hypogonadotrophic hypogonadism. Over 80 different mutations in this gene have been identified. We present three unrelated cases with variable clinical presentations, all with novel mutations in the DAX-1 gene.

High resolution melting analysis of almond SNPs derived from ESTs

High resolution melting curve (HRM) is a recent advance for the detection of SNPs. The technique measures temperature induced strand separation of short PCR amplicons, and is able to detect variation as small as one base difference between samples. It has been applied to the analysis and scan of mutations in the genes causing human diseases. In plant species, the use of this approach is limited. We applied HRM analysis to almond SNP discovery and genotyping based on the predicted SNP information derived from the almond and peach EST database. Putative SNPs were screened from almond and peach EST contigs by HRM analysis against 25 almond cultivars. All 4 classes of SNPs, INDELs and microsatellites were discriminated, and the HRM profiles of 17 amplicons were established. The PCR amplicons containing single, double and multiple SNPs produced distinctive HRM profiles. Additionally, different genotypes of INDEL and microsatellite variations were also characterised by HRM analysis. By sequencing the PCR products, 100 SNPs were validated/revealed in the HRM amplicons and their flanking regions. The results showed that the average frequency of SNPs was 1:114 bp in the genic regions, and transition to transversion ratio was 1.16:1. Rare allele frequencies of the SNPs varied from 0.02 to 0.5, and the polymorphic information contents of the SNPs were from 0.04 to 0.53 at an average of 0.31. HRM has been demonstrated to be a fast, low cost, and efficient approach for SNP discovery and genotyping, in particular, for species without much genomic information such as almond.

The impact of MLC transmitted radiation on EPID dosimetry for dynamic MLC beams

The purpose of this study was to experimentally quantify the change in response of an amorphous silicon (a-Si) electronic portal imaging device (EPID) to dynamic multileaf collimator (dMLC) beams with varying MLC-transmitted dose components and incorporate the response into a commercial treatment planning system (TPS) EPID prediction model. A combination of uniform intensity dMLC beams and static beams were designed to quantify the effect of MLC transmission on EPID response at the central axis of 10 x 10 cm2 beams, at off-axis positions using wide dMLC beam profiles, and at different field sizes. The EPID response to MLC transmitted radiation was 0.79 +/- 0.02 of the response to open beam radiation at the central axis of a 10 x 10 cm2 field. The EPID response to MLC transmitted radiation was further reduced relative to the open beam response with off-axis distance. The EPID response was more sensitive to field size changes for MLC transmitted radiation compared to open beam radiation by a factor of up to 1.17 at large field sizes. The results were used to create EPID response correction factors as a function of the fraction of MLC transmitted radiation, off-axis distance, and field size. Software was developed to apply the correction factors to each pixel in the TPS predicted EPID image. The corrected images agreed more closely with the measured EPID images in areas of intensity modulated fields with a large fraction of MLC transmission and, as a result the accuracy of portal dosimetry with a-Si EPIDs can be improved. Further investigation into the detector response function and the radiation source model are required to achieve improvements in accuracy for the general case.

Gastrointestinal nematode challenge induces some conserved gene expression changes in the gut mucosa of genetically resistant sheep

Sheep have a varying ability to resist infection with gastrointestinal nematodes. This ability is due in part to genetic differences that exist between individuals. In order to define these differences we have used real-time PCR to quantify gene expression responses in the gut mucosal surface of genetically resistant and susceptible sheep, following a nematode challenge. Expression profiles were determined in response to two different nematode species, Haemonchus contortus and Trichostrongylus colubriformis, and in divergent sheep originating from two different genetic backgrounds. Results show that the response generated differs between resistant and susceptible animals and is further impacted by the origin of the sheep and nematode species used for challenge. However, some conserved features of a response mounted by a resistant or a susceptible animal were identified. Genes found to be more abundantly expressed in resistant animals include markers of an early inflammatory response, several Toll-like receptors (TLR2, 4, 9) and free radical producing genes (DUOX1 and NOS2A). Conversely, genes differentiating susceptible animals indicate a prolonged response and development of a chronic inflammatory state, characterised by elevated expression of members of the NF-kappabeta signalling pathway (IKBKB and NFKBIA) together with delayed expression of regulatory markers such as IL2RA (CD25), IL10 and TGFbeta2. While multiple nematode response pathways were identified, the identification of conserved aspects of the response which associate with resistance provides evidence that alternative nematode control strategies, such as breeding for resistant animals, may be feasible.

Striking antigen recognition diversity in the Atlantic salmon T-cell receptor alpha/delta locus

The complete TCR alpha/delta locus of Atlantic salmon (Salmo salar) has been characterized and annotated. In the 900 kb TCR alpha/delta locus, 292 Valpha/delta segments and 123 Jalpha/delta segments were identified. Of these, 128 Valpha/delta, 113 Jalpha, and a Jdelta segment appeared to be functional as they lacked frame shifts or stop codons. This represents the largest repertoire of Valpha/delta and Jalpha segments of any organism to date. The 128 functional Valpha/delta segments could be grouped into 29 subgroups based upon 70% nucleotide similarity. Expression data confirmed the usage of the diverse repertoire found at the genomic level. At least 99 Valpha, 13 Vdelta 86 Jalpha, 1 Jdelta, and 2 Ddelta segments were used in TCR alpha or delta transcription, and 652 unique genes were identified from a sample of 759 TCRalpha cDNA clones. Cumulatively, the genomic and expression data suggest that the Atlantic salmon T-cell receptor has enormous capacity to recognize a wide diversity of antigens.

Identification of immuno-reactive proteins from a sheep gastrointestinal nematode, Trichostrongylus colubriformis, using two-dimensional electrophoresis and mass spectrometry

Gastrointestinal nematode infections of livestock animals are prevalent and costly problems worldwide. Currently, infections are controlled by anthelmintic chemicals but increasing drug resistance has prompted research interest to shift towards alternative methods of control such as vaccine development and selection of worm-resistant animals. The present study analyses proteins from Trichostrongylus colubriformis infective L3s that are recognised by IgG of immune sheep. Following protein separation via two-dimensional electrophoresis and Western blot probing with plasma from sheep resistant to T. colubriformis, mass spectrometry-based proteomic analyses were used to identify immuno-reactive protein spots. We were able to identify 28 immune targets, including aspartyl protease inhibitor, enolase, chaperone proteins, galectin, glycolytic enzymes, kinase, phosphatase and structural muscle proteins such as myosin, paramyosin, calponin and DIM-1. The data suggest that immune responses to T. colubriformis are dispersed over a relatively large number of parasite antigens, including several cytoplasmically expressed proteins. The results have new implications for understanding the molecular mechanisms that underpin host-parasite interaction during gastrointestinal nematode infections.

A Survey of Expressed Sequence Tags from the Rainbow Trout (Oncorhynchus Mykiss) Pituitary

The pituitary plays significant roles in the regulation of physiological processes. In the current study, expressed sequence tag data was obtained for 1,920 clones from a normalized mixed-sex pituitary cDNA library. From these 3,840 sequences, a total of 524 contigs were assembled and 1,256 unique singletons identified. Assignment of functional annotation was performed through BLAST and gene ontology term assignment. Through in silico comparative mapping homologs were identified for 354 of the unigene sequences. These data provide the first functional information on many of the transcripts present in the rainbow trout pituitary.

The format for the National Food Guide: performance and preference studies

This paper gives the main findings of research designed to inform decisions about the format of a food selection guide, subsequently published as the National Food Guide. The research involved 2074 members of the public and 230 professionals involved in nutrition education. Different formats for the guide were assessed for performance (how well the information was understood and recalled) and preference with a quota sample of C2 and D socioeconomic groups. Preferences were also assessed with a sample of various professionals involved in nutrition education. The investigations involved different versions of the guide which varied in shape, background colour, presentational style (whether the foods depicted were many or few, photographic or drawn) and in the wording of the food group headings. The key findings were that exposure to a guide can have a significant effect on people's understanding of guide concepts and that some aspects of the design enhanced that effect. In particular, guides which were in the shape of a tilted plate were better at conveying nutritional concepts than those which were pyramid-shaped. Members of the public and nutrition educators both preferred a plate shape but, whereas the public preferred a tilted plate to a flat plate, the nutrition educators thought that a flat plate would be more appealing to their clients than a tilted plate.

Interruption of enfuvirtide in HIV-1 infected adults with incomplete viral suppression on an enfuvirtide-based regimen

Many antiretroviral drugs continue to exert an anti-human immunodeficiency virus (HIV) benefit in the presence of drug resistance mutations. The degree to which enfuvirtide exerts continued antiviral activity in the presence of incomplete viral suppression has not been defined. To address this question, 25 subjects interrupted enfuvirtide while remaining on a stable background regimen. Enfuvirtide interruption was associated with an immediate but limited increase in plasma HIV-1 RNA levels. Enfuvirtide resistance waned rapidly in the absence of drug pressure and was no longer detectable by week 16 in most individuals. These data indicate that enfuvirtide has measurable antiviral activity in the setting of incomplete viral suppression. Although enfuvirtide resistance mutations are associated with significant fitness defects in vivo, the clinical significance of these mutations remains undefined.

Rate of viral evolution and risk of losing future drug options in heavily pretreated, HIV-infected patients who continue to receive a stable, partially suppressive treatment regimen

BACKGROUND

Many treatment-experienced, HIV-infected patients who have limited therapeutic options for complete viral suppression continue to receive a partially suppressive treatment regimen pending the availability of at least 2 new antiretroviral drugs. The major risk of this approach is ongoing viral evolution and the loss of future drug options.

METHODS

Antiretroviral-treated subjects with incomplete viral suppression were sampled from a clinic-based cohort. Inclusion criteria were receipt of a stable treatment regimen for > or = 120 days, a plasma HIV RNA load of > 500 copies/mL, and > or = 1 resistance mutation. Phenotypic and genotypic resistance testing was performed every 4 months.

RESULTS

The 106 patients who were eligible for the study had a median of 3 observations during a median of 11.3 months. An estimated 23% and 18% developed at least 1 new nucleoside analogue and 1 new protease inhibitor mutation at 1 year, respectively. An estimated 30% lost the phenotypic equivalent of 1 susceptible drug at 1 year. A lower number of total mutations at baseline was a significant predictor of developing a new nucleoside analogue mutation (P=.01). At 1 year, the probability that an existing mutation would become undetectable using population-based sequencing was 32%. There was a higher rate of change at nonresistance codons than at codons known to be associated with drug resistance.

CONCLUSIONS

Heavily pretreated patients with HIV infection who remain on a partially suppressive regimen have a measurable risk of losing future drug options, particularly those patients who have few baseline mutations. Resistance mutations vary over time, which suggests that the results of any single resistance test may not be representative of all mutations selected by a given treatment regimen.

Neutralizing antibody responses against autologous and heterologous viruses in acute versus chronic human immunodeficiency virus (HIV) infection: evidence for a constraint on the ability of HIV to completely evade neutralizing antibody responses

Acute human immunodeficiency virus (HIV) infection is associated with the rapid development of neutralization escape mutations. The degree to which viral evolution persists in chronic infection has not been well characterized, nor is it clear if all patients develop high-level neutralization antibody escape. We therefore measured neutralizing antibody responses against autologous and heterologous viruses in a cohort of acutely and chronically infected subjects (n = 65). Neutralizing antibody responses against both autologous virus and heterologous viruses were lower among individuals with acute infection than among those with chronic infection. Among chronically infected individuals, there was a negative correlation between the level of neutralizing antibodies against autologous virus and the level of viremia. In contrast, there was a positive correlation between the level of neutralizing antibodies against a panel of heterologous viruses and the level of viremia. Viral evolution, as defined by the presence of higher neutralizing titers directed against earlier viruses than against contemporaneous viruses, was evident for subjects with recent infection but absent for those with chronic infection. In summary, neutralizing antibody responses against contemporaneous autologous viruses are absent in early HIV infection but can be detected at low levels in chronic infection, particularly among those controlling HIV in the absence of therapy. HIV replication either directly or indirectly drives the production of increasing levels of antibodies that cross-neutralize heterologous primary isolates. Collectively, these observations indicate that although HIV continuously drives the production of neutralizing antibodies, there may be limits to the capacity of the virus to evolve continuously in response to these antibodies. These observations also suggest that the neutralizing antibody response may contribute to the long-term control of HIV in some patients while protecting against HIV superinfection in most patients.

Immediate transition to an implant-supported dentition

Immediate implant placement and loading is becoming increasingly acceptable. However, to be successful, very careful case selection is required, and even if this is achieved, the clinical situation that develops as soon as the natural teeth are removed may prove much less adequate for implant stability, positioning, and survival than anticipated. It makes sense to "over engineer" a case and to place more implants rather than fewer to ensure adequate support during the critical early phase of therapy, particularly when the implants are loaded at the time of placement. It also should be appreciated that immediate transition induces gross changes that can make it difficult to predict the final esthetic outcome.

A Randomized Pilot Study Comparing Combination Therapy plus Enfuvirtide versus a Treatment Interruption followed by Combination Therapy plus Enfuvirtide

Most individuals with multidrug-resistant HIV who switch to a new therapeutic regimen containing a single fully effective agent experience incomplete viral suppression. We postulated that interruption of antiretroviral therapy prior to the introduction of such a regimen would improve long-term virological outcomes. Thirty, three-class experienced, enfuvirtide-naive individuals with detectable drug-resistant viraemia were randomized to an immediate enfuvirtide/optimized-background treatment regimen or a 16-week treatment interruption followed by enfuvirtide/optimized-background treatment regimen. The median CD4+ T-cell count and viral load at study entry were 39 cells/mm and 4.72 log10 copies RNA/ml, respectively. There was no evidence of any virological or immunological benefit associated with the interruption. In multivariate analysis, only the baseline phenotypic susceptibility score was predictive of treatment response at week 48 ( P=0.009). Only 40% of individuals had evidence of a shift in drug-resistance genotype during the interruption. In summary, interrupting therapy prior to initiating salvage therapy in patients with advanced disease did not result in an improved virological response to enfuvirtide. The collective predictive activity of an enfuvirtide-containing regimen was important in predicting treatment response.

Malaria parasites can develop stable resistance to artemisinin but lack mutations in candidate genes atp6 (encoding the sarcoplasmic and endoplasmic reticulum Ca2+ ATPase), tctp, mdr1, and cg10

Resistance of Plasmodium falciparum to drugs such as chloroquine and sulfadoxine-pyrimethamine is a major problem in malaria control. Artemisinin (ART) derivatives, particularly in combination with other drugs, are thus increasingly used to treat malaria, reducing the probability that parasites resistant to the components will emerge. Although stable resistance to artemisinin has yet to be reported from laboratory or field studies, its emergence would be disastrous because of the lack of alternative treatments. Here, we report for the first time, to our knowledge, genetically stable and transmissible ART and artesunate (ATN)-resistant malaria parasites. Each of two lines of the rodent malaria parasite Plosmodium chabaudi chabaudi, grown in the presence of increasing concentrations of ART or ATN, showed 15-fold and 6-fold increased resistance to ART and ATN, respectively. Resistance remained stable after cloning, freeze-thawing, after passage in the absence of drug, and transmission through mosquitoes. The nucleotide sequences of the possible genetic modulators of ART resistance (mdr1, cg10, tctp, and atp6) of sensitive and resistant parasites were compared. No mutations in these genes were identified. In addition we investigated whether changes in the copy number of these genes could account for resistance but found that resistant parasites retained the same number of copies as their sensitive progenitors. We believe that this is the first report of a malaria parasite with genetically stable and transmissible resistance to artemisinin or its derivatives.

A randomized pilot study comparing combination therapy plus enfuvirtide versus a treatment interruption followed by combination therapy plus enfuvirtide

Most individuals with multidrug-resistant HIV who switch to a new therapeutic regimen containing a single fully effective agent experience incomplete viral suppression. We postulated that interruption of antiretroviral therapy prior to the introduction of such a regimen would improve long-term virological outcomes. Thirty, three-class experienced, enfuvirtide-naive individuals with detectable drug-resistant viraemia were randomized to an immediate enfuvirtide/optimized-background treatment regimen or a 16-week treatment interruption followed by enfuvirtide/optimized-background treatment regimen. The median CD4+ T-cell count and viral load at study entry were 39 cells/mm and 4.72 log10 copies RNA/ml, respectively. There was no evidence of any virological or immunological benefit associated with the interruption. In multivariate analysis, only the baseline phenotypic susceptibility score was predictive of treatment response at week 48 (P=0.009). Only 40% of individuals had evidence of a shift in drug-resistance genotype during the interruption. In summary, interrupting therapy prior to initiating salvage therapy in patients with advanced disease did not result in an improved virological response to enfuvirtide. The collective predictive activity of an enfuvirtide-containing regimen was important in predicting treatment response.

The periodontal prosthesis mode of transition to an implant-supported dentition

In recent years, implant-supported reconstructions have become a welcome alternative to dentures for those who have lost their natural dentition. While the benefits of the final implant-supported reconstruction may be obvious, the planning and execution of therapy to achieve this result may be bewildering to many dentists. Four main modes of transfer have evolved: an uncontrolled or "haphazard" transition; the traditional "dentures first" mode, an immediate transition, and a staged transition. This article proposes an additional mode of transition called periodontal prosthesis, which has the potential to make the transition process smoother and more predictable while providing optimal retention of alveolar supporting structures and generating optimal esthetics.

Molecular Transformations as a Way of Finding and Exploiting Consistent Local QSAR

The idea of a "transformation", making a small change to a chemical structure, for instance removing or replacing a substituent, is familiar to chemists. We suggest two ways of representing a transformation in silico, as a substructure descriptor difference vector, and as the set of atoms remaining once a maximum common substructure is eliminated. Such transformations can be filtered sensibly, and it is easy to compare one transformation to another. These representations have two applications. First, we can use these methods to automatically organize and display sets of closely related compounds such that any consistent local QSAR in a data set can be easily seen, the T-ANALYZE application. Second, we can suggest to a chemist how to change a molecule "on hand" to a more active one based on local QSAR for that activity, the T-MORPH application.

Substituting c-Jun N-terminal kinase-3 (JNK3) ATP-binding site amino acid residues with their p38 counterparts affects binding of JNK- and p38-selective inhibitors

c-Jun N-terminal kinase (JNK) activation is linked to the aberrant cell death in several neurodegenerative disorders, including Parkinson's and Alzheimer's disease. The sequence similarity among the JNK isoforms and fellow MAP kinase family member p38 has rendered the challenge of producing JNK3-specific inhibitors difficult. Using the crystal structure of JNK3 complexed with JNK inhibitors, potential compound-interacting amino acid residues were mutated to the corresponding residues in p38. The effects of these mutations on the kinetic parameters with three compounds were examined: a JNK3- (vs. p38-) selective inhibitor (SP 600125); a p38-selective inhibitor (Merck Z); and a potent combined JNK3 and p38 inhibitor (Merck Y). The data confirm the role of the JNK3 residues Ile-70 and Val-196 in both inhibitor and ATP-binding. Remarkably, the Ile-70-Val and Val-196-Ala mutations caused an increase and decrease, respectively, in the binding affinity of the p38-specific compound, Merck Z, of 10-fold. The Ile-70-Val effect may be due to the increased capacity of the active site to accommodate Merck Z, whereas the Val-196-Ala mutant may induce an unfavourable conformational change. Conservative mutations of the Asn-152 and Gln-155 residues inactivated the JNK3 enzyme, possibly interfering with protein folding in a critical hinge region of the protein.

Late onset neonatal anaemia due to maternal anti-Ge: possible association with destruction of eythroid progenitors

There have been no reports of severe haemolytic disease of the newborn (HDN) due to Gerbich (Ge) antibodies. Two babies with HDN due to anti-Ge3, both born to the same mother, are described. The anti-Ge appeared in the first pregnancy and was not detectable in the first trimester, the babies' reticulocyte and bilirubin values were not greatly elevated (similar to HDN due to Kell antibodies), and the anaemia in both cases was either not apparent or not severe until 2 to 4 weeks after birth. Ge antigens are found on glycophorins (GPs) C and D; GPC, like Kell, has been shown to be expressed early on erythroid progenitor cells. The maternal anti-Ge3 was shown to promote phagocytosis of Ge+ early erythroid progenitors by monocytes (similar to what has been reported with anti-K and K+ progenitor cells). Thus, anti-Ge3 may cause immune destruction of erythroid progenitors and possibly suppression of erythropoiesis (which would explain the reticulocyte and bilirubin values seen in both cases). Anti-Ge3 appears to be capable of causing severe HDN. We suggest that babies born to mothers with anti-Ge should have their haemoglobin concentrations monitored for signs of anaemia for several weeks after birth. Functional assays may prove useful.

Subcellular targeting of DISC1 is dependent on a domain independent from the Nudel binding site

Disrupted in schizophrenia 1 (DISC1) has been identified as a putative risk factor for schizophrenia and affective disorders through study of a Scottish family with a balanced (1;11) (q42.1;q14.3) translocation, which results in the disruption of the DISC1 locus and cosegregates with major psychiatric disease. Several other reports of genetic linkage and association between DISC1 and schizophrenia in a range of patient populations have added credibility to the DISC1-schizophrenia theory, but the function of the DISC1 protein is still poorly understood. Recent studies have suggested that DISC1 plays a role in neuronal outgrowth, possibly through reported interactions with the molecules Nudel and FEZ1. Here we have analyzed the DISC1 protein sequence to identify previously unknown regions that are important for the correct targeting of the protein and conducted imaging studies to identify DISC1 subcellular location. We have identified a central coiled-coil region and show it is critical for the subcellular targeting of DISC1. This domain is independent from the C-terminal Nudel binding domain highlighting the multidomain nature/functionality of the DISC1 protein. Furthermore, we have been able to provide the first direct evidence that DISC1 is localized to mitochondria in cultured cortical neurons that are dependent on an intact cytoskeleton. Surprisingly, Nudel is seen to differentially associate with mitochondrial markers in comparison to DISC1. Disruption of the cytoskeleton results in colocalization of Nudel and mitochondrial markers-the first observation of such a direct relationship. Mitochondrial dysfunction has been implicated to play a role in schizophrenia so we speculate that mutations in DISC1 or Nudel may impair mitochondrial transport or function, initiating a cascade of events culminating in psychiatric illness.

Discovery of Functionally Selective 7,8,9,10-Tetrahydro-7,10-ethano-1,2,4-triazolo[3,4-a]phthalazines as GABAA Receptor Agonists at the α3 Subunit

We have previously identified the 7,8,9,10-tetrahydro-7,10-ethano-1,2,4-triazolo[3,4-a]phthalazine (1) as a potent partial agonist for the alpha(3) receptor subtype with 5-fold selectivity in binding affinity over alpha(1). This paper describes a detailed investigation of the substituents on this core structure at both the 3- and 6-positions. Despite evaluating a wide range of groups, the maximum selectivity that could be achieved in terms of affinity for the alpha(3) subtype over the alpha(1) subtype was 12-fold (for 57). Although most analogues showed no selectivity in terms of efficacy, some did show partial agonism at alpha(1) and antagonism at alpha(3) (e.g., 25 and 75). However, two analogues tested (93 and 96), both with triazole substituents in the 6-position, showed significantly higher efficacy for the alpha(3) subtype over the alpha(1) subtype. This was the first indication that selectivity in efficacy in the required direction could be achieved in this series.

Issues in maintenance and repairs of wheelchairs: A pilot study

In this pilot study, we assessed wheelchair durability and its effect on user satisfaction. Specifically, we examined the characteristics of the participants' wheelchairs, the types of maintenance and repairs completed, and whether the participants' satisfaction was affected by problems with their wheelchairs. A convenience sample of 130 participants who used wheelchairs as their primary means of mobility was recruited. Participants completed a questionnaire about their wheelchairs, the maintenance and repair history, and their satisfaction levels. Results showed that 26% of the participants had completed a wheelchair repair in the past 6 months, 16% had completed general maintenance, and 27% had completed tire repairs. Neither hours of wheelchair use nor wheelchair age affected repair or maintenance frequency. Participants were generally satisfied with their wheelchairs. Better understanding of wheelchair maintenance and repair issues will guide improvements in wheelchair design and enhance the community participation of individuals who use wheelchairs.

A technique for performing antegrade selective cerebral perfusion without interruption of forward flow or cannula relocation for pediatric aortic arch reconstruction

New technology and advances in extracorporeal bypass circuitry and surgical techniques have drastically improved outcomes in infants with congenital heart defects. Hypothermia with circulatory arrest has fallen out of favor in many institutions over the last decade in part from data implicating even short circulatory arrest times to long-term neurologic sequelae. Implementing continuous cerebral perfusion techniques for aortic arch reconstruction is desirable in ameliorating neurologic complications because long-term survival of complex defects can be more routinely achieved. Many centers have implemented alternative means of alleviating cerebral ischemic periods by incorporating selective antegrade or retrograde cerebral perfusion techniques. The incidence of post-operative neurologic events is low when alternative cerebral perfusion techniques are used. Many techniques used to perform continuous cerebral perfusion involve brief periods of circulatory arrest, usually for perfusion cannula repositioning. Herein we describe a technique for performing continuous antegrade cerebral perfusion without a need to interrupt forward flow.

Conserved residues within the putative active site of gamma-secretase differentially influence enzyme activity and inhibitor binding

Gamma-secretase performs the final processing step in the generation of amyloid-beta (Abeta) peptides, which are believed to be causative for Alzheimer's disease. Presenilins (PS) are required for gamma-secretase activity and the presence of two essential intramembranous aspartates (D257 and D385) has implicated this region as the putative catalytic centre of an aspartyl protease. The presence of several key hydrogen-bonding residues around the active site of classical aspartyl proteases led us to investigate the role of both the critical aspartates and two nearby conserved hydrogen bond donors in PS1. Generation of cell lines stably overexpressing the D257E, D385E, Y256F and Y389F engineered mutations has enabled us to determine their role in enzyme catalysis and binding of a transition state analogue gamma-secretase inhibitor. Here we report that replacement of either tyrosine residue alters gamma-secretase cleavage specificity, resulting in an increase in the production of the more pathogenic Abeta42 peptide in both cells and membranous enzyme preparations, without affecting inhibitor binding. In contrast, replacement of either of the aspartate residues precludes inhibitor binding in addition to inactivation of the enzyme. Together, these data further incriminate the region around the intramembranous aspartates as the active site of the enzyme, targeted by transition state analogue inhibitors, and highlight the roles of individual residues.

Immune activation set point during early HIV infection predicts subsequent CD4+ T-cell changes independent of viral load

Although generalized T-cell activation is an important factor in chronic HIV disease pathogenesis, its role in primary infection remains poorly defined. To investigate the effect of immune activation on T-cell changes in subjects with early HIV infection, and to test the hypothesis that an immunologic activation “set point” is established early in the natural history of HIV disease, a prospective cohort of acutely infected adults was performed. The median density of CD38 molecules on CD4+ and CD8+ T cells was measured longitudinally in 68 antiretroviral-untreated individuals and 83 antiretroviral-treated individuals. At study entry, T-cell activation was positively associated with viremia, with CD8+ T-cell activation levels increasing exponentially at plasma HIV RNA levels more than 10 000 copies/mL. Among untreated patients, the level of CD8+ T-cell activation varied widely among individuals but often remained stable within a given individual. CD8+ T-cell activation and plasma HIV RNA levels over time were independently associated with the rate of CD4+ T-cell loss in untreated individuals. These data indicate that immunologic activation set point is established early in HIV infection, and that this set point determines the rate at which CD4+ T cells are lost over time.

Development and application of a salmonid EST database and cDNA microarray: data mining and interspecific hybridization characteristics

We report 80,388 ESTs from 23 Atlantic salmon (Salmo salar) cDNA libraries (61,819 ESTs), 6 rainbow trout (Oncorhynchus mykiss) cDNA libraries (14,544 ESTs), 2 chinook salmon (Oncorhynchus tshawytscha) cDNA libraries (1317 ESTs), 2 sockeye salmon (Oncorhynchus nerka) cDNA libraries (1243 ESTs), and 2 lake whitefish (Coregonus clupeaformis) cDNA libraries (1465 ESTs). The majority of these are 3' sequences, allowing discrimination between paralogs arising from a recent genome duplication in the salmonid lineage. Sequence assembly reveals 28,710 different S. salar, 8981 O. mykiss, 1085 O. tshawytscha, 520 O. nerka, and 1176 C. clupeaformis putative transcripts. We annotate the submitted portion of our EST database by molecular function. Higher- and lower-molecular-weight fractions of libraries are shown to contain distinct gene sets, and higher rates of gene discovery are associated with higher-molecular weight libraries. Pyloric caecum library group annotations indicate this organ may function in redox control and as a barrier against systemic uptake of xenobiotics. A microarray is described, containing 7356 salmonid elements representing 3557 different cDNAs. Analyses of cross-species hybridizations to this cDNA microarray indicate that this resource may be used for studies involving all salmonids.

Programs-that-work: CDC's guide to effective programs that reduce health-risk behavior of youth

In response to requests from educators for effective programs that reduce health-risk behavior among youth, the Centers for Disease Control and Prevention initiated "Programs-That-Work" (PTW) in 1992 to identify health education programs with credible evidence of effectiveness. CDC identified as PTW two programs to reduce tobacco use and eight programs to reduce sexual risk behaviors. Eligible programs undergo a two-step external review to examine quality of the research evidence and the extent to which the programs are practical for use by health educators. If CDC identifies a programs as a PTW on the basis of external review, the program is packaged and made available for dissemination to education and youth agencies. Communities ultimately make the decision about adopting a program, and CDC does not require their use. Thousands of educators have sought information about PTW through the CDC web site, informational brochures, and training.