Medical correlates of first-term attrition in US Navy personnel

INTRODUCTION

First-term attrition (FTA), or failure of a military service member to complete their initial service contract, is a major financial burden and source of lost manpower in the US Navy. The objective of the present study was to examine medical correlates of FTA using healthcare and disability rating data.

METHODS

In this retrospective cohort study, all US Navy-enlisted personnel between the years 2003 and 2018 with FTA (n=58 777) and regular discharge (n=203 084) were identified for analysis from accession dates in the Career History Archival Medical and Personnel System. Medical diagnoses from outpatient and inpatient records were abstracted from the Military Health System Data Repository. For a subgroup of the study population discharged with a disability rating (n=12 880), diagnoses were identified from the Integrated Disability Evaluation System. The FTA and regular discharge groups were compared using relative risks (RRs) and 95% CIs, and per cent differences for the disability subgroup analysis.

RESULTS

Compared with regular discharges, those with FTA were more likely to have outpatient and inpatient diagnoses for mental health disorders. Personality disorder yielded the strongest association with FTA in both outpatient (RR=10.45, 95% CI 9.79 to 11.16) and inpatient settings (RR=18.97, 95% CI 14.16 to 25.42). Other disorders associated with FTA included schizophrenia, substance-related disorders, poisoning by psychotropic agents and adjustment disorders. In the disability analysis, the FTA group relative to regular discharges had the largest per cent differences for 'arthritis, degenerative (hypertrophic or osteoarthritis)' (10.8% vs 2.5%) and 'tibia and fibula, impairment' (3.0% vs 0.4%).

CONCLUSIONS

This study provides evidence that FTA is associated with both mental and physical health conditions. Mental and physical factors related to FTA require further examination, particularly whether pre-enlistment screening or early career intervention could lead to mitigation strategies. Future research should extend this analysis to other services and population subgroups.

Adipokine Apelin/APJ Pathway Promotes Peritoneal Dissemination of Ovarian Cancer Cells by Regulating Lipid Metabolism

Adipose tissue, which can provide adipokines and nutrients to tumors, plays a key role in promoting ovarian cancer metastatic lesions in peritoneal cavity. The adipokine apelin promotes ovarian cancer metastasis and progression through its receptor APJ, which regulates cell proliferation, energy metabolism, and angiogenesis. The objective of this study was to investigate the functional role and mechanisms of the apelin-APJ pathway in ovarian cancer metastasis, especially in context of tumor cell-adipocyte interactions. When co-cultured in the conditioned media (AdipoCM) derived from 3T3-L1 adipocytes, which express and secrete high apelin, human ovarian cancer cells with high APJ expression showed significant increases in migration and invasion in vitro. We also found that cells expressing high levels of APJ had increased cell adhesion to omentum ex vivo, and preferentially "home-in" on the omentum in vivo. These apelin-induced pro-metastatic effects were reversed by APJ antagonist F13A in a dose-dependent manner. Apelin-APJ activation increased lipid droplet accumulation in ovarian cancer cells, which was further intensified in the presence of AdipoCM and reversed by F13A or APJ knockdown. Mechanistically, this increased lipid uptake was mediated by CD36 upregulation via APJ-STAT3 activation, and the lipids were utilized in promoting fatty acid oxidation via activation of AMPK-CPT1a axis. Together, our studies demonstrate that adipocyte-derived apelin activates APJ-expressing tumor cells in a paracrine manner, promoting lipid uptake and utilization and providing energy for ovarian cancer cell survival at the metastatic sites. Hence, the apelin-APJ pathway presents a novel therapeutic target to curb ovarian cancer metastasis. IMPLICATIONS: Targeting the APJ pathway in high-grade serous ovarian carcinoma is a novel strategy to inhibit peritoneal metastasis.

Abstract TMIM-070: APELIN PROMOTES OMENTAL METASTASIS OF OVARIAN CANCER CELLS

PURPOSE: Ovarian cancer (OvCa) is mainly metastasized to the peritoneal cavity and omentum, an organ primarily composed of adipocytes. Adipocytes produce adipokines including apelin involved in initiating angiogenesis and promote the initial homing of tumor cells to omentum through adipokine secretion. Apelin and its receptor APJ mediates glucose/energy metabolism and angiogenesis. The study objective is to assess the functional role of apelin/APJ pathway in omental metastasis of OvCa and associated benefits from antagonizing this pathway as a novel treatment strategy against OvCa metastasis.

METHODS: Mouse adipocyte cell line 3T3-L1 were used to obtain adipocyte-derived conditioned media (adipo-CM). Apelin concentrations in adipo-CM were quantified using Western blot and ELISA. Migration and invasion of human OvCa cell lines (OVCAR-5APJ and OVCAR-8) were determined in vitro in the presence of adipo-CM. In vivo homing and ex vivo adhesion assays were performed to study the role of apelin/APJ pathway in attracting and attaching APJ-overexpressing OvCa cells to the omentum.

RESULTS: Apelin expression was 2.5 fold higher in mature adipocytes compared to that in pre-adipocytes. Mature adipocytes secreted 0.8-1 ng/mL of apelin in the CM. In vivo, high APJ expression increased 'homing-in' of OvCa cells by 2.75-fold to the omentum. Adipo-CM increased transwell migration (3-3.5 fold) and invasion (3.5-4 fold) of OvCa cells in vitro. Adhesion of APJ high expression OvCa cells to mice omentum ex vivo increased by 1.5 fold. These apelin-induced pro-metastatic effects were reversed by apelin-specific antagonist (F13A) in a dose-dependent manner.

CONCLUSION: We found that apelin/ APJ pathway potentially promotes OvCa metastasis to omentum and F13A effectively inhibited apelin-induced effects.

Citation Format: Samrita Dogra, Deepika Neelakantan, Maulin Mukeshchandra Patel, Beth Griesel, Ann Olson, Florea Lupu, and Sukyung Woo1. APELIN PROMOTES OMENTAL METASTASIS OF OVARIAN CANCER CELLS [abstract]. In: Proceedings of the 12th Biennial Ovarian Cancer Research Symposium; Sep 13-15, 2018; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2019;25(22 Suppl):Abstract nr TMIM-070.

A retrospective cohort study comparing dairy calf treatment decisions by farm personnel with veterinary observations of clinical signs

Antimicrobials are frequently administered to calves with diarrhea, despite evidence suggesting questionable efficacy. Even if efficacious, providing the appropriate therapy to an animal requires accurate disease detection. The objective of this study was to use previously collected data and compare clinical scoring by a veterinarian to treatment decisions by on-farm personnel. Data describing daily clinical scores and farm treatments were previously collected from 4 farms for calves from birth to age 28 d. In this data set, a total of 460 calves were enrolled. Daily observations and clinical assessments were made on each farm by the same veterinarian, for a total of 12,101 calf observation days. Farm personnel made all treatment decisions based on their own observations, and these treatments were recorded by study personnel. Overall, the cumulative incidence of a calf exhibiting at least one abnormal clinical sign over the 28-d observation period was 0.93, with cumulative incidences of 0.85 and 0.33 for diarrhea and dehydration, respectively. The cumulative incidence of any treatment (including antibiotics and electrolytes) was 0.85, although the majority of treatments used an antimicrobial. The farm-specific probabilities that a calf with clinical signs of dehydration or diarrhea, respectively, received fluid or electrolyte therapy ranged from 0.08 to 0.27 and 0.03 to 0.12. These probabilities were greater for the day a clinical sign was first observed. The farm-specific probabilities that a calf with clinical signs of diarrhea received an antimicrobial was 0.23 to 0.65, and the probability that a calf exhibiting clinical signs of respiratory disease received an antimicrobial was 0.33 to 0.76. The first observation of diarrhea had similar probabilities to those for all observations of diarrhea. There was greater probability of treatment for calves with their first observed abnormal respiratory signs. Probabilities that treatment with antimicrobials, or fluids or electrolytes, was associated with an abnormal clinical sign were low-that is, calves received treatments in the absence of any abnormal clinical signs. This study illustrates incongruity between treatment decisions by calf treaters (the designated personnel on each farm responsible for calf health assessment and treatment decisions) and those of an observer using a clinical scoring system to identify calves with abnormal clinical signs. These findings indicate opportunities and the need for dairy farmers and advisors to evaluate calf treatment protocols, reasons for treatment, and training programs for calf health and disease detection, as well as to develop monitoring programs for treatment protocol compliance and health outcomes following therapy.

Distribution and evolution of het gene homologs in the basidiomycota

In filamentous fungi a system known as somatic incompatibility (SI) governs self/non-self recognition. SI is controlled by a regulatory signaling network involving proteins encoded at the het (heterokaryon incompatible) loci. Despite the wide occurrence of SI, the molecular identity and structure of only a small number of het genes and their products have been characterized in the model fungi Neurospora crassa and Podospora anserina. Our aim was to identify and study the distribution and evolution of putative het gene homologs in the Basidiomycota. For this purpose we used the information available for the model fungi to identify homologs of het genes in other fungi, especially the Basidiomycota. Putative het-c, het-c2 and un-24 homologs, as well as sequences containing the NACHT, HET or WD40 domains present in the het-e, het-r, het-6 and het-d genes were identified in certain members of the Ascomycota and Basidiomycota. The widespread phylogenetic distribution of certain het genes may reflect the fact that the encoded proteins are involved in fundamental cellular processes other than SI. Although homologs of het-S were previously known only from the Sordariomycetes (Ascomycota), we also identified a putative homolog of this gene in Gymnopus luxurians (Basidiomycota, class Agaricomycetes). Furthermore, with the exception of un-24, all of the putative het genes identified occurred mostly in a multi-copy fashion, some with lineage and species-specific expansions. Overall our results indicated that gene duplication followed by gene loss and/or gene family expansion, as well as multiple events of domain fusion and shuffling played an important role in the evolution of het gene homologs of Basidiomycota and other filamentous fungi.

Immunoproteomics strategy for automation of chemoresistance and chemosensitivity array

20076

Background: Chemotherapy sensitivity and resistance assays (CSRAs) often guide therapeutic regimen selection based on patient cancer cells response to chemotherapeutics in culture. Current CSRAs rely on highly time- and skill- dependent biochemical and microscopic endpoint assays of apoptosis. Instead, the assay under development uses immunoproteomic array readout of biomarkers. Such automation may broaden the use of CSRAs for guiding clinical use of increasingly costly chemotherapeutic options. Methods: Specimens from 30 ovarian cancer patients were cultured with and without cisplatinum according to established CSRA procedures (http://weisenthal.org/w_ovarian_cp.pdf). Cells pelleted and fixed at experimental points (0 and 96 hrs cisplatin, and 96 hrs non-treated) were paraffin embedded for construction of immunoproteomic microarrays. A panel of 57 NIH cancer cell lines was similarly arrayed. Protein profiling is performed with monospecific antibodies for 35 select markers of cell cycle, apoptosis, cell signalling, and transcription. Immunostaining results, including rate of cell death and marker expression level are quantitated manually (immunoscore assigned for cell core) and automatically (algorithm by Aperio, Inc). Results: Evaluation of readouts differentiates responders from non-responders aiming to predict clinical chemotherapy outcome. For a subset of imunoproteomic markers, observed expression corresponds to either induced apoptosis or to cisplatin resistance. Selected markers were subjected to cytologic analysis and time line westerns; results corroborate protein profiling data. Correspondence to the results of the classic CSRAs and individual patient therapeutic response will be unblinded. Conclusions: Use of immunoproteomic arrays to replicate classic CSRAs by establishing concordant results may allow automated guidance for chemotherapeutic choices.

[Table: see text]

RNAi Codex: a portal/database for short-hairpin RNA (shRNA) gene-silencing constructs

Use of RNA interference (RNAi) in forward genetic screens is proliferating. Currently, short-interfering RNAs (siRNAs) and short-hairpin RNAs (shRNAs) are being used to silence genes to tease out functional information. It is becoming easier to harness RNAi to silence specific genes, owing to the development of libraries of readymade shRNA and siRNA gene-silencing constructs by using a variety of sources. RNAi Codex, which consists of a database of shRNA related information and an associated website, has been developed as a portal for publicly available shRNA resources and is accessible at . RNAi Codex currently holds data from the Hannon–Elledge shRNA library and allows the use of biologist-friendly gene names to access information on shRNA constructs that can silence the gene of interest. It is designed to hold user-contributed annotations and publications for each construct, as and when such data become available. We will describe features of RNAi Codex and explain the use of the tool.

Consequences of immunogenicity to the therapeutic monoclonal antibodies ReoPro and Remicade

The clinical consequences of immune antibodies generated to abciximab (ReoPro) and infliximab (Remicade) are described. Abciximab, a chimaeric Fab fragment that binds to the beta3 integrin of the GPIIb/IIIa and alphavbeta3 receptors on human platelets, is approved in the US and Europe for use in percutaneous coronary intervention (PCI) to prevent cardiac ischaemic complications. The effects of induced antibodies upon the safety and efficacy of repeat administration of abciximab have been evaluated in the ReoPro Re-administration Registry Study, in which 5.7% of patients were HACA positive before re-treatment. An interim evaluation of 1000 patients has indicated that re-administration of abciximab can be accomplished in the setting of PCI with an acceptable safety and efficacy profile. Infliximab is a chimaeric IgG1 antibody specific for human TNFalpha, and is approved in the US and Europe for the acute treatment of the signs and symptoms of Crohn's disease and for the chronic treatment of rheumatoid arthritis (RA). The incidence of antibodies to infliximab is reported to be approximately 10%; however, an inverse dose-immunogenicity relationship was observed, indicating that higher doses of infliximab (> or = 3 to 10 mg/kg) could reduce the incidence of immune antibodies. The induction of immune antibodies could also be reduced by concomitant administration of low-dose methotrexate and other immunosuppressant agents. Although antibodies to infliximab appeared to be associated with lower serum infliximab concentrations and a slightly higher incidence of infusion reactions, these immune antibodies were generally not associated with a reduction in clinical efficacy. In addition, the antibodies induced to infliximab are specific for infliximab, and do not cross-react with other currently available therapeutic antibodies.

Separating effects of orthographic similarity and contour summation in the identification of masked letter strings

We separated effects of contour summation and orthographic similarity under masking conditions, by comparing identification with simultaneous and sequentially presented letter strings, which either did or did not overlap spatially. With overlapping simultaneous stimuli, performance was better for strings with similar contours than for strings with the same letters (the orthographic similarity condition). This suggests that contour summation effects were strongest in the condition where stimuli had similar contours. With sequential presentations, performance in the similar contour and the orthographically similar conditions was equated when the stimuli were overlapping. However, effects of contour summation decreased when prime and target letters were spatially displaced, whereas performance in the orthographically similar condition was maintained. We conclude that effects of orthographic similarity can be distinguished from effects of contour summation, under masking conditions.

The effects of case mixing on word recognition: evidence from a PET study

The early stages of visual word recognition were investigated by scanning participants using PET as they took part in implicit and explicit reading tasks with visually disrupted stimuli. CaSe MiXiNg has been shown in behavioral studies to increase reaction times (RTs) in naming and other word recognition tasks. In this study, we found that during both an implicit (feature detection) task and an explicit word-naming task, mixed-case words compared to same-case words produced increased activation in an area of the right parietal cortex previously associated with visual attention. No effect of case was found in this area for pseudowords or consonant strings. Further, lowering the contrast of the stimuli slowed RTs as much as case mixing, but did not lead to the same increase in right parietal activation. No significant effect of case mixing was observed in left-hemisphere language areas. The results suggest that reading mixed-case words requires increased attentional processing. However, later word recognition processes may be relatively unaffected by the disruption in presentation.

Children and guns in a well child cohort

BACKGROUND

The purpose of this study was to estimate the extent of and to identify predictors of preadolescent gun use in a well child cohort with matched parent and child data.

METHODS

We analyzed self-report questionnaires from children and their parents using conditional logistic regression models. Questionnaires were given to 3,145 ten- to twelve-year-old children and 3,145 parents enrolled by their pediatricians in a prevention cohort study.

RESULTS

Thirty-two percent of the children lived in households with guns. Children and parents generally agreed about the presence of guns in their homes; 17% had access to unlocked guns in their homes; 22% had fired guns. In this preadolescent cohort, firing guns was associated with being male, having guns in the home, having friends who use guns, and initiation of alcohol use.

CONCLUSIONS

In this well child cohort, significant numbers of preadolescent, healthy boys in white, middle-class U.S. homes have access to guns, are using guns, and have friends who use guns. These children are also early alcohol adopters. Safety interventions with parents of preadolescents about the risks for accidental injury, death, and suicide due to child gun use may prove beneficial.

Monocyte chemoattractant protein 1 (MCP-1) in temporal arteritis and polymyalgia rheumatica

OBJECTIVE

To examine the localisation of monocyte chemoattractant protein 1 (MCP-1) in the inflamed vessel wall in temporal arteritis (TA) and to measure MCP-1 in plasma both in patients with TA and patients with polymyalgia rheumatica (PMR).

METHODS

By immunohistochemical techniques MCP-1 was localised to the vessel wall in patients with TA. In TA, PMR, and healthy controls MCP-1 was quantified by enzyme linked immunosorbent assay (ELISA) in plasma.

RESULTS

MCP-1 was localised to the majority of mononuclear cells, some smooth muscle cells, and giant cells in the arterial biopsy specimens from 12 patients with histologically verified TA. In all sections, including the vasa vasorum, the endothelium stained positive. In the intima 73% (range 57-91%), in the media 49% (range 32-67%), and in the adventitia 74% (range of 62-91%) of all cells stained positive. In plasma MCP-1 was significantly raised in untreated TA (n=33) and untreated PMR (n=27) compared with healthy controls (n=12). Untreated TA plasma levels of MCP-1 (mean 391 pg/ml (range 82-778 pg/ml)) were similar to untreated PMR plasma levels (mean 402 pg/ml (range 29-1153 pg/ml)), and no significant difference was found between the two groups of patients. In both patients with TA and patients with PMR no correlation was found between the plasma level of MCP-1 and the erythrocyte sedimentation rate, haemoglobin concentration, and CD4/CD8 ratio.

CONCLUSIONS

These results show that MCP-1 plays a part in the disease processes of TA and PMR.

Differential effects of word length and visual contrast in the fusiform and lingual gyri during reading

Previous studies have shown differential responses in the fusiform and lingual gyri during reading and suggested that the former is engaged in processing local features of visual stimuli and the latter is engaged in global shape processing. We used positron emission tomography in order to investigate how these regions are modulated by two common variables in reading: word length (three, six and nine letters) and perceptive similarity to the background (high and low contrast). Increasing both word length and visual contrast had a positive monotonic effect on activation in the bilateral fusiform. However, in the lingual gyrus, activation increased with increasing word length but decreased with increasing contrast. On the basis of previous studies, we suggest that (i) increasing word length increases the demands on both local feature and global shape processing, but (ii) increasing visual contrast increases the demands on local feature processing while decreasing the demands on global shape processing.

Fractionating the binding process: neuropsychological evidence distinguishing binding of form from binding of surface features

We present neuropsychological evidence demonstrating that the binding of form elements into shapes dissociates from the binding of surface detail to shape. Data are reported from a patient with bilateral parietal lesions, GK, who manifests left-side visual extinction along with many illusory conjunctions when asked to discriminate both surface and form information about stimuli. We show that there are effects of grouping on both extinction and illusory conjunctions when the tasks require report of object shape. In contrast, illusory conjunctions involving surface and form information were unaffected by grouping based on shape. In addition, grouping was stronger when forms were presented within the same hemifield than when they appeared in different hemifields, whilst illusory conjunctions of form and colour occurred equally often within and across hemifields. These results support a two-stage account of visual binding: form elements are first bound together locally into shapes, and this is followed by a second stage of binding in which shapes are integrated with surface details. The second but not the first stage of binding is impaired in this patient.

Systematic analysis of deficits in visual attention

A variety of impairments in visual attention can follow damage to the brain. The authors develop systematic methods for analyzing such impairments in terms of C. Bundesen's (1990) Theory of Visual Attention and apply these in a group of 9 patients with parietal lobe lesions and variable spatial neglect. In whole report, patients report letters from brief, vertical arrays in left or right visual field. The results show substantial, largely bilateral impairments in processing capacity, implying a major nonlateralized aspect to neglect. In partial report, arrays contain 1 or 2 letters in red and/or green. The task is to report only those letters in a specified target color. In addition to the expected bias against left-sided letters, patients show striking, bilateral preservation of top-down control, or attentional priority for targets. The results show how differentiation of attentional impairments can be informed by a theory of normal function.

Systematic analysis of deficits in visual attention

A variety of impairments in visual attention can follow damage to the brain. The authors develop systematic methods for analyzing such impairments in terms of C. Bundesen's (1990) Theory of Visual Attention and apply these in a group of 9 patients with parietal lobe lesions and variable spatial neglect. In whole report, patients report letters from brief, vertical arrays in left or right visual field. The results show substantial, largely bilateral impairments in processing capacity, implying a major nonlateralized aspect to neglect. In partial report, arrays contain 1 or 2 letters in red and/or green. The task is to report only those letters in a specified target color. In addition to the expected bias against left-sided letters, patients show striking, bilateral preservation of top-down control, or attentional priority for targets. The results show how differentiation of attentional impairments can be informed by a theory of normal function.

Guideline for the management of pediatric idiopathic constipation and soiling. Multidisciplinary team from the University of Michigan Medical Center in Ann Arbor

OBJECTIVE

To develop an evidence-based guideline for the primary pediatric care of children (birth to 18 years old) with idiopathic constipation and soiling.

DATA SOURCES

References were identified through a MEDLINE search from January 1975 through January 1998 to address 3 focus questions: (1) the best path to early, accurate diagnosis; (2) best methods for adequate clean-out; and (3) best approaches to promote patient and family compliance with management.

DATA SELECTION

Twenty-five references were identified.

DATA EXTRACTION

References were reviewed by a multidisciplinary team and graded according to the following criteria: randomized controlled trial; controlled trial, no randomization; observational study; and expert opinion. Evidence tables were developed for each focus question.

DATA SYNTHESIS

An algorithm and clinical care guideline were developed by consultation and consensus among team members. Emphasis was placed on methods to promote early identification of pediatric idiopathic constipation and soiling, to recognize points of referral, and to increase patient and family compliance with treatment through use of education, developmentally based interventions, and variables for tracking success of management.

CONCLUSION

An algorithm and guideline for pediatric idiopathic constipation and soiling are presented for use by primary care physicians.

Importance of factor VIIa Gla-domain residue Arg-36 for recognition of the macromolecular substrate factor X Gla-domain

Macromolecular substrate docking with coagulation enzyme-cofactor complexes involves multiple contacts distant from the enzyme's catalytic cleft. Here we characterize the binding of the Gla-domain of macromolecular substrate coagulation factor X to the complex of tissue factor (TF) and VIIa. Site-directed mutagenesis of charged residue side chains in the VIIa Gla-domain identified Arg-36 as being important for macromolecular substrate docking. Ala substitution for Arg-36 resulted in an increased KM and a decreased rate of X activation. X with a truncated Gla-domain was activated by mutant and wild-type VIIa at indistinguishable rates, demonstrating that Arg-36 interactions require a properly folded Gla-domain of the macromolecular substrate. VIIa Arg-36 was also required for effective docking of the X Gla-domain in the absence of phospholipid, demonstrating that the Gla-domain of VIIa participates in protein-protein interactions with X. In the absence of TF, the mutant VIIa had essentially normal function, indicating that the cofactor positions VIIa's Gla-domain for optimal macromolecular substrate docking. Computational docking suggests multiple charge complementary contacts of the X Gla-domain with TF.VIIa. A prominent interaction is made by the functionally important X residue Gla-14 with the center of the extended docking site created by residues in the carboxyl module of TF and the contiguous VIIa Gla-domain. These data demonstrate the functional importance of interactions of the Gla-domains of enzyme and substrate, and begin to elucidate the molecular details of the ternary TF.VIIa.X complex.

Developmental surface dysgraphia: what is the underlying cognitive impairment?

The purpose of this study was to investigate the cognitive causes underlying spelling difficulties in a case of developmental surface dysgraphia, AW. Our results do not support a number of possibilities that could be the cause of AW's poor orthographic lexicon, including difficulties in phonological processing, phonological short-term memory, configurational visual memory, and lexical semantic memory. We have found instead that AW performs poorly in tasks that involve detection of the order of adjacent letters in a word or the order of adjacent units in strings of consonants or symbols. Finally, he performs poorly in tasks that involve reconstructing the order of a series of complex visual characters (Japanese and Hindi characters) especially when these are presented sequentially. We advance the hypothesis that AW's poor spelling and good reading skills stem from an underlying pattern of cognitive abilities where a very good visual configurational memory is coupled with a poor ability to encode serial order. This may have resulted in a holistic word-based reading strategy, which, together with the original problem of encoding order, may have had detrimental effects for the acquisition of spelling.

The expression of MDP-1, a component of Drosophila embryonic basement membranes, is modulated by apoptotic cell death

Using a novel monoclonal antibody we have studied the expression of a large proteoglycan-type molecule in Drosophila embryos. This molecule is secreted exclusively by migratory, embryonic hemocytes/macrophages and was therefore named MDP-1 for Macrophage-Derived Proteoglycan-1. Expression of MDP-1 begins late during hemocyte differentiation, after these cells have left their birthplace in the head mesoderm. At this time, macrophages are engaged in extracellular matrix deposition and the phagocytosis of cell debris generated by apoptotic events in various parts of the embryo, in particular from the developing central nervous system. Embryos deficient for programmed cell death display a greatly reduced amount of MDP-1 deposition in tissues that normally undergo morphogenetic cell death. This suggests a regulatory role for apoptosis in the terminal differentiation of Drosophila hemocytes. MDP-1 is initially deposited around the developing central nervous system and is later found in basement membrane structures surrounding various other organs, such as the gut, Malpighian tubules and part of the tracheal system. The temporal and localized deposition of MDP-1 suggests that it may play a role in delineating the central nervous system structure during axonogenesis and may participate in the formation of a functional 'blood-brain barrier' in Drosophila.

Crystal structures of the inactive D30N mutant of feline immunodeficiency virus protease complexed with a substrate and an inhibitor

Crystal structures of complexes of a D30N mutant of feline immunodeficiency virus protease (FIV PR) complexed with a statine-based inhibitor (LP-149), as well as with a substrate based on a modification of this inhibitor (LP-149S), have been solved and refined at resolutions of 2.0 and 1.85 A, respectively. Both the inhibitor and the substrate are bound in the active site of the mutant protease in a similar mode, which also resembles the mode of binding of LP-149 to the native protease. The carbonyl oxygen of the scissile bond in the substrate is not hydrated and is located within the distance of a hydrogen bond to an amido nitrogen atom from one of the two asparagines in the active site of the enzyme. The nitrogen atom of the scissile bond is 3.25 A from the conserved water molecule (Wat301). A model of a tetrahedral intermediate bound to the active site of the native enzyme was built by considering the interactions observed in all three crystal structures of FIV PR. Molecular dynamics simulations of this model bound to native wild-type FIV PR were carried out, to investigate the final stages of the catalytic mechanism of aspartic proteases.

Disruption to word or letter processing? The origins of case-mixing effects

MiXeD-cAsE stimuli have long been used to test whether word recognition is based on holistic visual information or preliminary letter identification. However, without knowing which properties of mixed-case stimuli disrupt processing, it is not possible to determine which visual units mediate word recognition. The present studies examined the effects of case mixing on word and nonword naming as a function of (a) whether spaces were inserted between letters and (b) whether letter size was alternated independent of letter case. The results suggest that case-mixing disruption effects are due to at least 2 factors: the introduction of inappropriate grouping between letters with the same size and case, and the disruption of transletter features. The data support a model of visual lexical access based on the input from multiple visually based units.

Molecular docking programs successfully predict the binding of a beta-lactamase inhibitory protein to TEM-1 beta-lactamase

Crystallization of the 1:1 molecular complex between the beta-lactamase TEM-1 and the beta-lactamase inhibitory protein BLIP has provided an opportunity to put a stringent test on current protein-docking algorithms. Prior to the successful determination of the structure of the complex, nine laboratory groups were given the refined atomic coordinates of each of the native molecules. Other than the fact that BLIP is an effective inhibitor of a number of beta-lactamase enzymes (KI for TEM-1 approximately 100 pM) no other biochemical or structural data were available to assist the practitioners in their molecular docking. In addition, it was not known whether the molecules underwent conformational changes upon association or whether the inhibition was competitive or non-competitive. All six of the groups that accepted the challenge correctly predicted the general mode of association of BLIP and TEM-1.

Structure and organization of two closely related low-temperature-induced dhn/lea/rab-like genes in Arabidopsis thaliana L. Heynh

We have isolated a 7 kb EcoRI genomic fragment from Arabidopsis thaliana which contains, in a tandem arrangement, two closely related dhn/lea/rab-like genes, lti29 (formerly named lti45) and cor47, corresponding to previously isolated cDNA clones. Both transcripts have been shown to accumulate in response to low temperature (LT), abscisic acid (ABA) and dehydration. Alignment of the amino acid sequences of the deduced polypeptides showed that they are 67% identical. The calculated molecular masses of the two polypeptides were 29 kDa for LTI29 and 30 kDa for COR47. Both polypeptides contain one conserved serine-stretch and three lysine-rich repeats characteristic of DHN/LEA/RAB-like proteins. In addition, both LTI29 and COR47 harbour and N-terminal acidic repeat only found in a few members amongst the DHN/LEA/RAB proteins. The close distance between the two genes (separated by 2.7 kb) and their tandem organization in the A. thaliana genome as well as the overall homology at the nucleotide sequence level of the coding region suggest that the two genes have evolved through a duplication event. This seems to be a common feature among A. thaliana LT-responsive genes.

Non-spatial extinction following lesions of the parietal lobe in humans

Efficient behaviour in the visual environment requires selection between stimuli competing for control of action. Many current models of selection are spatial: relevant objects are chosen by attending to their locations. The unilateral stimulus extinction observed following lesions of the parietal lobe provides evidence for spatial selection. Such patients may identify a single stimulus presented in their contralesional field, but can fail to detect the same stimulus when a competing stimulus is shown simultaneously on the ipsilesional side. Here we demonstrate that extinction need not be spatial in nature, but may be determined by characteristics of the objects to be selected. In two patients with parietal lobe lesions and poor spatial localization, pictures extinguished words and closed shapes extinguished open shapes. This object-based extinction indicates the existence of biases within non-spatial selection mechanisms which are independent of biases produced by spatial selection mechanisms. We suggest that selection of objects for action requires that the 'winners' produced by the independent competitive biases for selection are bound together within distinct neural areas concerned with object properties and space.

Characterization and differential expression of dhn/lea/rab-like genes during cold acclimation and drought stress in Arabidopsis thaliana

We have characterized cDNAs for two new dhn/lea/rab (dehydrin, late embryogenesis-abundant, responsive to ABA)-related genes from Arabidopsis thaliana. The two genes were strongly induced in plants exposed to low temperature (4 degrees C) and were accordingly designated lti45 and lti30 (low temperature-induced). The lti45 gene product contains the conserved serine stretch and three lysine-rich repeats characteristic of DHN/LEA/RAB proteins and is very similar to another low temperature-responsive protein of A. thaliana, COR47 [17]. Both proteins have the same repeat structure and an overall amino acid identity of 64%. This structural similarity of the proteins and the tandem array of the genes suggest that this gene pair arose through a duplication. The other polypeptide, LTI30, consists of several lysine-rich repeats, a structure found in CAP85, a low temperature- and water stress-responsive protein in spinach [41] and similar proteins found in wheat [20]. The expression pattern of the five dhn/lea/rab-related genes (cor47, dhnX, lti30, lti45 and rab18) identified so far in A. thaliana, was characterized in plants exposed to low temperature, drought and abscisic acid (ABA). Expression of both lti30 and lti45 was mainly responsive to low temperature similar to cor47. The lti45 and lti30 genes show only a weak response to ABA in contrast to cor47, which is moderately induced by this hormone. The three genes were also induced in severely water-stressed plants although the expression of lti30 and lti45 was rather low. In contrast to these mainly low temperature-induced genes, the expression of rab18 was strongly induced both in water-stressed and ABA-treated plants but was only slightly responsive to cold. The dhnX gene showed a very different expression pattern. It was not induced with any of the treatments tested but exhibited a significant constitutive expression. The low-temperature induction of the genes in the first group, lti30 and lti45, is ABA-independent, deduced from experiments with the ABA-deficient (aba-1) and ABA-insensitive (abil) mutants of A. thaliana, whereas the induction of rab18 is ABA-mediated. The expression of dhnX was not significantly affected in the ABA mutants.

Efficacy of anterior gastric fundoplication in the treatment of gastroesophageal reflux in infants and children

Anterior gastric fundoplication (AGF) has been performed at the University of Michigan since 1988. To objectively evaluate the long-term efficacy of the AGF, the authors performed a study of children who had undergone AGF between June 1988 and June 1990 (n = 46). Six of them died of unrelated causes. Twenty-two consented to follow-up evaluation that included parental interview, physical examination, upper gastrointestinal series (UGI), 24-hour esophageal pH probe monitoring (EpH), and a liquid-phase gastric emptying study. Twenty patients (74%) remained asymptomatic, and only one child required reoperation. Four asymptomatic patients exhibited gastroesophageal reflux (GER) by UGI, and three others by EpH. Three children were noted to have delayed gastric emptying. These results compare favorably with data previously reported from this institution of a 5-year follow-up of children after Nissen fundoplication. There is a trend toward improved efficacy (87% v 74%; P = .12), decreased reoperation rate (4% v 14%; P = .11), and less severe complications. The present study shows that AGF is effective treatment for GER when evaluated by objective studies and is comparable in therapeutic efficacy and safety to the Nissen fundoplication.

Diffusion coefficient of cyclic GMP in salamander rod outer segments estimated with two fluorescent probes

Experiments have demonstrated that single photoisomerizations in amphibian and primate rods can cause the suppression of 3-5% of the dark circulating current at the response peak (Baylor, D. A., T. D. Lamb, and K. W. Yau. 1979. J. Physiol. (Lond.). 288:613-634; Baylor, D. A., B. J. Nunn, and J. L. Schnapf. 1984. J. Physiol. (Lond.). 357:575-607). These results indicate that the change in [cGMP] effected by a single isomerization must spread longitudinally over at least the corresponding fractional length of the outer segment. The effective longitudinal diffusion coefficient, Dx, of cGMP is thus an important determinant of rod sensitivity. We report here measurements of the effective longitudinal diffusion coefficients, Dx, of two fluorescently labeled molecules: 5/6-carboxyfluorescein and 8-(fluoresceinyl)thioguanosine 3',5'-cyclic monophosphate, introduced into detached outer segments via whole-cell patch electrodes. For these compounds, the average time for equilibration of the entire outer segment with the patch pipette was approximately 6 min. Fluorescence images of rods were analyzed with a one-dimensional diffusion model that included limitations on transfer between the electrode and outer segment and the effects of intracellular binding of the dyes. The analyses yielded estimates of Dx of 1.9 and 1.0 microns 2.s-1 for the two dyes. It is shown that these results place an upper limit on Dx for cGMP of 11 microns2.s-1. The actual value of Dx for cGMP in the rod will depend on the degree of intracellular binding of cGMP. Estimates of the effective buffering power for cGMP in the rod at rest range from two to six (Lamb and Pugh, 1992; Cote and Brunnock, 1993). When combined with these estimates, our results predict that for cGMP itself, Dx falls within the range of 1.4-5.5 microns 2.s-1.

Preclinical studies on deoxycoformycin and deoxyadenosine as pharmacologic T cell purging tools

Deoxycoformycin (dCf) is a potent toxin to T lymphocytes in human peripheral blood and bone marrow. In the presence of deoxyadenosine (dAdo), dCf inhibits T cell function as measured by DNA synthesis induced by stimuli in the rank order of mixed lymphocyte culture greater than murine monoclonal antibody OKT3 greater than phytohemagglutinin. Approximately two logs of human bone marrow T cells were removed by 24 h of incubation with dCf and dAdo at doses that preserved colony-forming ability of the treated marrow. A semi-closed system of isolating mononuclear cells in large volumes using density gradient centrifugation was developed. Using this system, it was found that dCf and dAdo could remove about two logs of T lymphocytes after 24 h of incubation when the cells were incubated in large volumes at a relatively high concentration (10(7) cells/ml). This system appears well suited for purging T lymphocytes from human bone marrow before clinical transplantation.