Evaluating the effects of hypoxic storage on platelet function and health using a novel storage system

BACKGROUND

Thousands of units of whole blood (WB) and blood components are transfused daily to treat trauma patients. Improved methods for blood storage are critical to support trauma-related care. The Hemanext ONE® system offers a unique method for hypoxic storage of WB, with successfully demonstrated storage of clinically viable RBCs. This work evaluated the system for the storage of WB, focusing on platelet health and function.

STUDY DESIGN AND METHODS

WB was collected from healthy donors and processed through the Hemanext ONE® system. Hemoglobin oxygen saturation (HbSO2) levels of WB were depleted to 10%, 20%, or 30% of total HbSO2 and then stored in PVC bags sealed in oxygen-impermeable bags (except for normoxic control) with samples collected on days 1, 7, and 14 post-processing. Flow cytometry assessed the activation and apoptosis of platelets. Clot dynamics were assessed based on aggregometry and thromboelastography assays, as well as thrombin generation using a calibrated-automated thrombogram method.

RESULTS

Hypoxic storage conditions were maintained throughout the storage period. Hypoxia triggered increased lactate production, but pH changes were negligible compared to normoxic control. Storage at 10% HbSO2 had a significant impact on platelet function, resulting in increased activation and reduced clot formation and aggregation. These effects were less significant at 20% and 30% HbSO2.

DISCUSSION

This study indicates that platelets are sensitive to hypoxic storage and suffer significant metabolic and functional deterioration when stored at or below 10% HbSO2.

Scholarship in anesthesiology: the role of critical appraisal, literature review, quality improvement, journal club, and presentation skills

If asked to describe the term "anesthesiologist scholar", one may receive a variety of definitions depending on the individual's area of practice, location in the world, and the generation in which they trained. In this article, we review the roles of five core elements that make an anesthesiologist a "scholar": skills in critical appraisal, literature review, quality improvement, journal club participation, and presentation delivery. Although this list of scholarly components is not comprehensive, review of each element's role in the everyday practice and training of physicians will offer insight into their evolution and may offer a glimpse into the future of anesthesiologist scholars. Overall, through the dissemination, recognition, and support of scholarship through these practices, we will continue to achieve meaningful outcomes for our patients and promote a culture of collaboration worldwide. We should ensure that these topic areas become a bedrock of medical education globally, and we must foster opportunities for those who have already completed training to develop and master these skills as a part of their clinical and academic practice.

Double-Dose Desogestrel: Is it Effective in Adolescent Menstrual Dysfunction?

STUDY OBJECTIVE

Adolescent menstrual dysfunction (AMD) is a common cause of iron deficiency anemia and absences from school. The management of AMD with single- and double-dose desogestrel is largely on the basis of anecdotal evidence. Our aim was to describe the effectiveness and safety of both dosing strategies in our clinic cohort to help guide future management.

DESIGN

Local service evaluation with retrospective analysis of clinic notes.

SETTING

Adolescent gynecology clinic in a tertiary pediatric center in the North West of England.

PARTICIPANTS

Adolescent girls (10-18 years of age) with AMD (n = 129).

INTERVENTIONS

Single-dose (75 µg) desogestrel vs double-dose (150 µg) desogestrel.

MAIN OUTCOME MEASURES

Prevalence of amenorrhea and light spotting, side effects, and discontinuation rates of both dosing regimens.

RESULTS

Forty-three of 87 (49%) adolescent girls who started treatment with a double dose of desogestrel were amenorrheic/experienced light spotting, compared with 7/40 (18%) of girls who started treatment with a single dose (P = .001). Patients taking a double dose of desogestrel were less likely to discontinue overall (double: 45/89 [51%]; vs single: 35/40 [88%]; P < .001) and there was no evidence of an increase in nonbleeding side effects (double: 30/89 [34%]; vs single: 15/40 [38%]; P = .68).

CONCLUSION

Our findings provide evidence that a double dose of desogestrel is associated with a higher prevalence of amenorrhea and light spotting compared with a single dose in adolescent girls with AMD. However, larger studies are needed to further inform clinical guidelines.

0069 Sleep in Drosophila is Regulated by the Chromatin Remodeling Factor ISWI

Introduction

Sleep is commonly disrupted in patients with neurodevelopmental disorders (NDDs). Despite strong clinical associations between disrupted sleep and other NDD symptoms, we lack an understanding of how these are pathophysiologically related. Drosophila melanogaster exhibit essential characteristics of human sleep and have well-defined neural circuits underlying learning and social behaviors. This represents an ideal system to investigate the mechanistic interaction between disrupted sleep and other behavioral dysfunctions in NDDs.

Methods

We performed a reverse genetic RNAi-based screen targeting Drosophila homologs of human genes within NDD-associated risk loci. Pan-neuronal knockdown of risk genes was achieved using the Gal4-UAS system.

Results

Pan-neuronal knockdown of ISWI led to dramatic deficits in sleep and circadian arrhythmicity in the adult fly. Across species, ISWI and its homologs are ATP-dependent chromatin remodelers that regulate gene expression important for neural differentiation. We found that depleting ISWI also leads to memory and social deficits. ISWI functions during dissociable temporal windows of pre-adult development and in different circuits to establish different adult behaviors. The sleep phenotype associated with ISWI knockdown mapped to a specific population of cells. RNA-Seq of developing brains during the window important for sleep deficits revealed significant transcriptional changes in genes associated with nervous system development, suggesting ISWI acts in the development of sleep regulatory circuits. Finally, mutations in the human homologs of ISWI, SMARCA1/5, have been implicated in NDDs. Expressing either SMARCA1/5 in the setting of ISWI knockdown differentially rescued adult deficits.

Conclusion

Identification of ISWI provides a platform for unraveling pleiotropic behavioral effects from an NDD risk gene. Sleep, circadian rhythms, memory, and social behaviors are affected by ISWI knockdown, and map to different developmental periods and circuits. In addition, SMARCA1/5 differentially rescue adult behaviors, suggesting NDD-causing mutations in these genes may affect different behaviors. Current work aims to determine how human mutations in SMARCA1/5 affect behaviors.

Support

This work was supported by NIH K08 NS090461 (MSK) and T32 HL007953 (NNG), Hearst Foundation Fellowship 2018 (NNG), Burroughs Welcome Career Award for Medical Scientists, March of Dimes Basil O’Connor Scholar Award, and Sloan Research Fellowship (MSK).

Abstract P6-15-03: MBC Connect™, an open-access, patient-reported registry of de-identified data from patients living with metastatic breast cancer

Metastatic breast cancer (MBC) remains an incurable disease and is the cause of nearly all deaths from breast cancer. Several barriers prevent efficient research into various questions about living with MBC. A key unmet need is a national database for MBC patient-reported outcomes, which does not exist anywhere in the world. Furthermore, compartmentalized data prevents broad collaborative efforts. Treatment patterns and responses, survival times, and metastatic patterns are not documented systematically and remain unavailable. Large-scale data extraction is challenging, and expensive, and electronic medical records do not provide information regarding patient experiences. Methods: MBC Connect™ was created to help overcome these barriers. MBC Connect, which is sponsored by the Metastatic Breast Cancer Alliance, is a multi-national registry of participant reported information about their experience of MBC. MBC Connect allows MBC patients to voluntarily provide information about their disease, treatment outcomes, and experience of living with their disease so that researchers can gain insight into unmet needs in MBC. MBC Connect has three main goals: 1. Establish an interactive registry of patient-entered, de-identified data for MBC. 2. Create an open-access portal for researchers to study these data. 3. Create a connection between investigators of clinical trials and clinical research studies and registered users who may be interested in clinical trials. Results: MBC Connect collects, via the use of a mobile app (on a smartphone or tablet, iOS and Android compatible) or via a website for desktop users, participant consent, general patient characteristics and demographics, disease characteristics, genetics and tumor mutations, treatment history, quality of life data, and clinical trial experience. This information can be provided by patients living with MBC or their caregiver. The data are collected from responses to surveys and via creation of a treatment profile. The data are de-identified and made available on an open-access Researcher portal, allowing them to be used to advance multiple areas of research into MBC, including both medical treatment aspects and quality of life issues. An interactive feature of MBC Connect is that researchers may submit a request for participants to answer additional surveys. Participants may also be notified about clinical trials for which they may be eligible. In addition, participants will regularly receive “Insights,” which are engaging bytes of information related to MBC. Insights can offer general information about the disease, upcoming events, and other facts, or they can be personalized for the participant based on the information he or she has entered the registry. Conclusions: MBC Connect is a novel platform that aims to accelerate MBC research by providing open access to patient-reported, de-identified data about patients living with MBC. The overarching objective of this technologic initiative is to increase patient engagement with the research community.

Citation Format: Campbell L, De La Torre K, Williams CE, Mertz SA, Pollastro T, Hutton A, Newby J, Ellis MJ, Iyengar NM, Hurlbert MS. MBC Connect™, an open-access, patient-reported registry of de-identified data from patients living with metastatic breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-15-03.

Differential Life History Trait Associations of Aphids with Nonpersistent Viruses in Cucurbits

The diversity of vectors and fleeting nature of virus acquisition and transmission renders nonpersistent viruses a challenge to manage. We assessed the importance of noncolonizing versus colonizing vectors with a 2-yr survey of aphids and nonpersistent viruses on commercial pumpkin farms. We quantified aphid alightment using pan traps, while testing leaf samples with multiplex RT-PCR targeting cucumber mosaic virus (CMV), zucchini yellow mosaic virus (ZYMV), watermelon mosaic virus (WMV), and papaya ringspot virus (PRSV). Overall, we identified 53 aphid species (3,899 individuals), from which the melon aphid, Aphis gossypii Glover, a pumpkin-colonizing species, predominated (76 and 37% of samples in 2010 and 2011, respectively). CMV and ZYMV were not detected, but WMV and PRSV were prevalent, both regionally (WMV: 28/29 fields, PRSV: 21/29 fields) and within fields (infection rates = 69 and 55% for WMV in 2010 and 2011; 28 and 25% for PRSV in 2010 and 2011). However, early-season samples showed extremely low infection levels, suggesting cucurbit viruses are not seed-transmitted and implicating aphid activity as a causal factor driving virus spread. Interestingly, neither noncolonizer and colonizer alightment nor total aphid alightment were good predictors of virus presence, but community analyses revealed species-specific relationships. For example, cowpea aphid (Aphis craccivora Koch) and spotted alfalfa aphid (Therioaphis trifolii Monell f. maculata) were associated with PRSV infection, whereas the oleander aphid (Aphis nerii Bover de Fonscolombe) was associated with WMV spread within fields. These outcomes highlight the need for tailored management plans targeting key vectors of nonpersistent viruses in agricultural systems.

Differential expression of candidate salivary effector proteins in field collections of Hessian fly, Mayetiola destructor

Evidence is emerging that some proteins secreted by gall-forming parasites of plants act as effectors responsible for systemic changes in the host plant, such as galling and nutrient tissue formation. A large number of secreted salivary gland proteins (SSGPs) that are the putative effectors responsible for the physiological changes elicited in susceptible seedling wheat by Hessian fly, Mayetiola destructor (Say), larvae have been documented. However, how the genes encoding these candidate effectors might respond under field conditions is unknown. The goal of this study was to use microarray analysis to investigate variation in SSGP transcript abundance amongst field collections from different geographical regions (southeastern USA, central USA, and the Middle East). Results revealed significant variation in SSGP transcript abundance amongst the field collections studied. The field collections separated into three distinct groups that corresponded to the wheat classes grown in the different geographical regions as well as to recently described Hessian fly populations. These data support previous reports correlating Hessian fly population structure with micropopulation differences owing to agro-ecosystem parameters such as cultivation of regionally adapted wheat varieties, deployment of resistance genes and variation in climatic conditions.

Errors during the preparation of drug infusions: a randomized controlled trial

BACKGROUND

We investigated the extent and frequency of dose errors and treatment delays made as a consequence of preparing drug infusions at the bedside, rather than using pre-filled syringes.

METHODS

Forty-eight nurses with critical care experience volunteered to take part in this randomized, blinded, controlled study conducted in the simulation centre of an urban hospital. They assisted in the management of a simulated patient with septic shock. Vasopressor infusions were prepared either by diluting concentrated drugs from ampoules or were provided in syringes pre-filled beforehand by an intensive care unit resident.

RESULTS

The time taken for the infusion to be started and the final concentration of the drugs were measured. We also measured the concentration of infusions prepared by a pharmacist and a pharmaceutical company. Nurses took 156 s to start infusions when using pre-filled syringes compared with 276 s when preparing them de novo, a mean delay of 106 s [95% confidence interval (CI) 73-140 s, P<0.0001]. One infusion prepared from ampoules contained one-fifth of the expected concentration of epinephrine; another contained none at all. Medication errors were 17.0 times less likely when pre-filled syringes were used (95% CI 5.2-55.5), and infusions prepared by pharmacy and industry were significantly more likely to contain the expected concentration (P<0.001 for norepinephrine and P=0.001 for epinephrine).

CONCLUSIONS

Providing drug infusions in syringes pre-filled by pharmacists or pharmaceutical companies would reduce medication errors and treatment delays, and improve patient safety. However, this approach would have substantial financial implications for healthcare providers, especially in less developed countries.

Comparative analysis of genetic background in eight near-isogenic wheat lines with different H genes conferring resistance to Hessian fly

Near-isogenic lines (NILs) are useful for plant genetic and genomic studies. However, the strength of conclusions from such studies depends on the similarity of the NILs’ genetic backgrounds. In this study, we investigated the genetic similarity for a set of NILs developed in the 1990s to study gene-for-gene interactions between wheat ( Triticum aestivum L.) and the Hessian fly ( Mayetiola destructor (Say)), an important pest of wheat. Each of the eight NILs carries a single H resistance gene and was created by successive backcrossing for two to six generations to susceptible T. aestivum ‘Newton’. We generated 256 target region amplification polymorphism (TRAP) markers and used them to calculate genetic similarity, expressed by the Nei and Li (NL) coefficient. Six of the NILs (H3, H5, H6, H9, H11, and H13) had the highly uniform genetic background of Newton, with NL coefficients from 0.97 to 0.99. However, genotypes with H10 or H12 were less similar to Newton, with NL coefficients of 0.86 and 0.93, respectively. Cluster analysis based on NL coefficients and pedigree analysis showed that the genetic similarity between each of the NILs and Newton was affected by both the number of backcrosses and the genetic similarity between Newton and the H gene donors. We thus generated an equation to predict the number of required backcrosses, given varying similarity of donor and recurrent parent. We also investigated whether the genetic residues of the donor parents that remained in the NILs were related to linkage drag. By using a complete set of ‘Chinese Spring’ nullisomic-tetrasomic lines, one third of the TRAP markers that showed polymorphism between the NILs and Newton were assigned to a specific chromosome. All of the assigned markers were located on chromosomes other than the chromosome carrying the H gene, suggesting that the genetic residues detected in this study were not due to linkage drag. Results will aid in the development and use of near-isogenic lines for studies of the functional genomics of wheat.

Proteolytic activity during cortical development is distinct from that involved in hypoxic ischemic injury

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases involved in brain development and the etiology of adult cerebral injuries. In this study, we determined the MMP-2 and 9 responses following hypoxic ischemia (HI) injury in the developing brain. First, we characterized the developmental changes of MMP activity in the rat brain from embryonic day 18 (E18) to postnatal day 120 (P120). MMP-2 activity was high from E18 to P3 and decreased with age (P< or =0.001), while MMP-9 activity was not detectable. MMP-2 immunoreactivity was closely associated with differentiating cortical plate and subplate neurons. Next, we characterized the proteolytic changes after unilateral HI brain injury in 3- (P3) and 21- (P21) day-old rats. Zymography revealed that in the P21 rat brain, MMP-9 activity (150 and 92 kDa forms) was increased at 6 h and remained elevated 24 h post-injury in the ipsilateral injured hemisphere (P< or =0.001), whereas there was a gradual increase in MMP-2 (65 kDa) activity, reaching a peak at 5 days (P< or =0.001). Similarly, quantitative real time polymerase chain reaction (qRT-PCR) indicated significant elevations in MMP-9 and MMP-2 mRNA expression in the injured cortex (P< or =0.05) and hippocampus (P< or =0.05) at 1 and 5 days post-injury, respectively in the P21 rat brain. In the P3 rat brain, zymography results revealed that both pro (92 kDa) and cleaved (87 kDa) MMP-9 activities were upregulated in the ipsilateral injured hemisphere from 6 h to 1 day after injury (P< or =0.001). In contrast, cleaved MMP-2 (60 kDa) was only moderately upregulated at 6 h (P< or =0.01), while pro MMP-2 (65 kDa) levels were unaffected. MMP-9 mRNA expression was also increased at 6 h (P< or =0.05) following injury at P3, whereas MMP-2 expression remained unchanged compared with the uninjured contralateral hemisphere. Immunohistochemistry indicated that MMP-9 protein expression was localized predominantly to neurons and peri-vascular astrocytes in the affected regions at early time points, whereas MMP-2 was present on reactive astrocytes surrounding the infarct at later time points. Together, these results indicate that MMP-2 may be primarily associated with the development and differentiation of cortical plate neurons and wound recovery processes. Conversely, MMP-9 appeared to be associated with more acute processes during the period of lesion development.

Prolactin is involved in glial responses following a focal injury to the juvenile rat brain

A cerebral growth hormone axis is activated following brain injury in the rat and treatment with growth hormone is neuroprotective. We have now investigated whether the closely related prolactin axis has similar properties following injury to the developing rat brain. From one day following a unilateral hypoxic ischemic injury, prolactin immunoreactivity was increased in the affected cortex parallel to the development of the injury (P<0.001). Initial prolactin and prolactin receptor staining on penumbral neurons progressively decreased whereas astrocytes remained strongly immunopositive. Reactive microglia also became strongly prolactin immunoreactive. Unlike growth hormone, central treatment with prolactin failed to rescue neurons in this paradigm. This was confirmed in vitro; rat prolactin failed to protect neurons under conditions for which growth hormone was neuroprotective. However, prolactin had trophic and pro-proliferative effects on glia (P<0.001). We confirmed the expression of the prolactin receptor in vitro by reverse transcriptase polymerase chain reaction, and show its strong association with astrocytes as compared with neurons by immunocytochemistry. In summary, we show for the first time that hypoxia ischemia induces a robust activation of the prolactin axis in regions of the cerebral cortex affected by injury. The lack of neuroprotective properties in vivo and in vitro indicates that, unlike growth hormone, prolactin is not directly involved in neuronal rescue in the injured brain. Its strong relation to glial reactions and its gliatrophic effects suggest that the prolactin axis is primarily involved in a gliogenic response during recovery from cerebral injury.

Identification and mapping of H32, a new wheat gene conferring resistance to Hessian fly

H32 is a newly identified gene that confers resistance to the highly pervasive Biotype L of the Hessian fly [ Mayetiola destructor (Say)]. The gene was identified in a synthetic amphihexaploid wheat, W-7984, that was constructed from the durum 'Altar 84' and Aegilops tauschii. This synthetic wheat is one of the parents of the marker-rich ITMI population, which consists of 150 recombinant inbred lines (RILs) derived by single-seed descent from a cross with 'Opata 85'. Linkage analysis of the H32 locus in the ITMI population placed the gene between flanking microsatellite (SSR) markers, Xgwm3 and Xcfd223, at distances of 3.7 and 1.7 cM, respectively, on the long arm of chromosome 3D. The Xgwm3 primers amplified codominant SSR alleles, a 72 bp fragment linked in coupling to the resistance allele and an 84 bp fragment linked in repulsion. Primers for the SSR Xcfd223 amplified a 153 bp fragment from the resistant Synthetic parent and a 183 bp fragment from the susceptible Opata line. Deletion mapping of the flanking Xgwm3 and Xcfd223 markers located them within the 3DL-3 deletion on the distal 19% of the long arm of chromosome 3D. This location is at least 20 cM proximal to the reported 3DL location of H24, a gene that confers resistance to Biotype D of the Hessian fly. Tight linkage of the markers will provide a means of detecting H32 presence in marker-assisted selection and gene pyramiding as an effective strategy for extending durability of deployed resistance.

Isolation and characterization of rice mutants compromised in Xa21-mediated resistance to X. oryzae pv. oryzae

The rice gene, Xa21, confers resistance to diverse races of Xanthomonas oryzae pv. oryzae (Xoo) and encodes a receptor-like kinase with leucine-rich repeats in the extra-cellular domain. To identify genes essential for the function of the Xa21 gene, 4,500 IRBB21 ( Xa21 isogenic line in IR24 background) mutants, induced by diepoxybutane and fast neutrons, were screened against Philippine race six (PR6) Xoo for a change from resistance to susceptibility. From two greenhouse screens, 23 mutants were identified that had changed from resistant to fully (6) or partially (17) susceptible to PR6. All fully susceptible mutants carried rearrangements at the Xa21 locus as detected by PCR and Southern hybridization. For the partially susceptible mutants, no changes were detected at the Xa21 locus based on Southern and PCR analyses. However, two of these mutants were confirmed via genetic analysis to have mutations at the Xa21 locus. Partially susceptible mutants exhibited variation in level of susceptibility to different Xoo strains, suggesting that they may carry different mutations required for the Xa21-mediated resistance. The mutants identified in this study provide useful materials for dissecting the Xa21-mediated resistance pathway in rice.

Adsorption of oppositely charged polyelectrolyte/surfactant complexes at the air/water interface: formation of interfacial gels

The adsorption and complexation of polystyrene sulfonate (a highly charged anionic polyelectrolyte) and dodecyltrimethylammonium bromide (a cationic surfactant) at the air-water interface can lead to interfacial gels that strongly influence foam-film drainage and stability. The formation and characteristics of these gels have been studied by combining surface tension, ellipsometry, and foam-film drainage experiments. Simultaneously, the solution electromotive force is measured and used to track the polymer-surfactant interactions in the bulk solution. We find that surface gelation occurs above the critical aggregation concentration in solution but before bulk precipitation of the polymer-surfactant complexes. Furthermore, we reveal that strong readsorption of polymer-surfactant complexes occurs during the resolubilization of the precipitated complexes at high surfactant concentrations (i.e., >>critical micelle concentration). Seemingly overlooked in the past, this readsorption significantly influences the surface rheological properties and foam-film drainage of these systems.

Phenotypic assessment and mapped markers for H31, a new wheat gene conferring resistance to Hessian fly (Diptera: Cecidomyiidae)

A new source of resistance to the highly virulent and widespread biotype L of the Hessian fly, Mayetiola destructor (Say), was identified in an accession of tetraploid durum wheat, Triticum turgidum Desf., and was introgressed into hexaploid common wheat, Triticum aestivum L. Genetic analysis and deletion mapping revealed that the common wheat line contained a single locus for resistance, H31, residing at the terminus of chromosome 5BS. H31 is the first Hessian fly-resistance gene to be placed on 5BS, making it unique from all previously reported sources of resistance. AFLP analysis identified two markers linked to the resistance locus. These markers were converted to highly specific sequence-tagged site markers. The markers are being applied to the development of cultivars carrying multiple genes for resistance to Hessian fly biotype L in order to test gene pyramiding as a strategy for extending the durability of deployed resistance.

Neuroprotective effects of the N-terminal tripeptide of IGF-1, glycine-proline-glutamate, in the immature rat brain after hypoxic-ischemic injury

Insulin growth factor 1 (IGF-1) has an important role in brain development and is strongly expressed during recovery after a hypoxic-ischemic injury. Some of its central actions could be mediated through the N-terminal tripeptide fragment of IGF-1: Gly-Pro-Glu (GPE). The neuroprotective properties of GPE given after a moderate injury in the developing rat brain were evaluated and the binding sites of [(3)H]GPE characterised by autoradiography. After right unilateral injury, GPE or vehicle (V) was injected in the right lateral ventricle (i.c.v.) or in the peritoneal cavity (i.p.) of 21-day-old rats. The percentage of surviving neurons in CA1-2 of the hippocampus was higher in the animals treated with 30 microg of GPE i.c.v. (V: 7.7+/-4.9%, GPE: 26.4+/-7.5%, P=0.02) and 300 microg i.p. (V: 30.2+/-9.1%, GPE: 68.8+/-10.6%, P=0.02) than in animals receiving vehicle. I.p. injection of 300 microg of GPE (V: 78.4+/-7.5%, GPE: 88.4+/-3.2%, P=0.04) was also neuroprotective in the lateral cortex. I.c.v. injection of [(3)H]GPE suggested binding to glial cells in the white matter tracts, the cortex and striatum as opposed to neurons. Although the precise mode of action of GPE is unknown, this study suggests that local administration of GPE is neuroprotective after brain HI injury via glial cells. In addition, systemic administration of GPE showed a more widespread neuroprotective effect. GPE may represent a complementary pathway for central and systemic IGF-1's antiapoptotic effects.

HIV-1 infected immune competent mononuclear phagocytes influence the pathways to neuronal demise

Secretory products from HIV-1-infected immune-competent mononuclear phagocytes (MP) damage neuronal dendritic arbor (Zheng et al., 2001). The mechanism behind neuronal injury and whether it is species and/or viral strain dependent is not fully understood. To these ends, we investigated whether HIV-1-infected and lipopolysaccharide (LPS)-activated MDM elicit neuronal injury in primary human neurons. Neuronal damage was compared to that seen in rat neurons. Utilizing a spectrum of HIV-1 strains to infect human monocyte-derived macrophages (MDM), productive viral replication proved necessary, but not sufficient, for neuronal injury. Neuronal demise was induced by virion-free HIV-1-infected and immune-activated MDM culture supernatants. Maximal alterations in glutamate mediated neuronal signaling, resulted from exposure to secretory products from HIV-1-infected and immune-activated MDM. Apoptosis was the predominant mechanism of cell death induced by HIV-1-infected and LPS-treated MDM. Importantly, neuronal injury and increases in calcium influx mediated by HIV-1-infected and immune-activated MDM culture supernatants was partially blocked by the N-methyl D-aspartate (NMDA) receptor antagonist, MK 801. These data support a primary role for immune-activation in MP neurotoxic activities. The upregulation of NMDA receptor sensitive soluble factors and neuronal apoptosis by HIV-1-infected and immune-activated MDM provide unique insights into links between soluble factors, produced as a consequence of MP immunity, and neuronal demise in HAD.

Growth hormone as a neuronal rescue factor during recovery from CNS injury

There is growing evidence to suggest that growth hormone plays a role in the growth and development of the CNS. Specifically, growth hormone has been implicated in promoting brain growth, myelination, neuronal arborisation, glial differentiation and cognitive function. Here we investigate if growth hormone has a role in the recovery from an unilateral hypoxic-ischaemic brain injury. Using moderate (15 min hypoxia) and severe (60 min hypoxia) models of hypoxic-ischaemia in juvenile rats and standard immunohistochemical techniques, we found intense growth hormone-like immunoreactivity present within regions of cell loss by 3 days (P<0.05). Growth hormone-like immunoreactivity was observed on injured neurones, myelinated axons, glial cells within and surrounding infarcted tissue and on the choroid plexus plus ependymal cells within the injured hemisphere. The pattern of immunoreactivity suggests that (a) growth hormone (or a growth hormone-like substance) is transported via the cerebrospinal fluid and (b) that growth hormone (or a growth hormone-like substance) is acting in a neurotrophic manner specifically targeted to injured neurones and glia. To test this hypothesis we treated a moderate hypoxic-ischaemic brain injury with 20 microg of rat growth hormone by intracerebroventricular infusion starting 2 h after injury (n=12/group). After 3 days the animals were killed and the extent of neuronal loss quantified. Growth hormone treatment reduced neuronal loss in the frontoparietal cortex (P<0.001), hippocampus (P<0.01) and dorsolateral thalamus (P<0.01) but not in the striatum. This spatial distribution of the neuroprotection conveyed by growth hormone correlates with the spatial distribution of the constitutive neural growth hormone receptor, but not with the neuroprotection offered by insulin-like growth factor-I treatment in this model. These results suggest that some of the neuroprotective effects of growth hormone are mediated directly through the growth hormone receptor and do not involve insulin-like growth factor-I induction.In summary, we have found that a growth hormone-like factor increased in the brain in the days after injury. In addition, treatment with growth hormone soon after an hypoxic-ischaemic injury reduced the extent of neuronal loss. These results further suggest that a neural growth hormone axis is activated during recovery from injury and that this may act to restrict the extent of neuronal death.

ST waveform changes during repeated umbilical cord occlusions in near-term fetal sheep

OBJECTIVE

This study was undertaken to determine whether changes in the fetal ST waveform during repeated umbilical occlusion reflect the development of hypotension and acidosis.

STUDY DESIGN

Chronically instrumented, near-term fetal sheep received 1-minute total umbilical cord occlusion either every 5 minutes for 4 hours (1:5 group, n = 8), or every 2.5 minutes until blood pressure fell <20 mm Hg on 2 successive occlusions (1:2.5 group, n = 8).

RESULTS

Umbilical cord occlusion caused variable decelerations, with sustained hypertension in the 1:5 group and little change in acid-base status (pH = 7.34 +/- 0.07 after 4 hours). In contrast, the 1:2.5 group showed progressive hypotension and metabolic acidemia (pH 6.92 +/- 0.1 after the final occlusion). There was a marked increase in ST waveform height during occlusions; this increase was greater in the 1:2.5 group (P <.001), but there was overlap between the groups. ST waveform height between occlusions was significantly higher in the 1:2.5 group (P <.001) until negative and biphasic ST waveforms developed in these fetuses between occlusions in the final 30 minutes.

CONCLUSION

ST waveform elevation occurs during umbilical cord occlusions but only crudely reflects the severity of hypoxia. Interocclusion waveform height may be a better reflection of the severity of hypoxia. The appearance of biphasic and negative waveforms between occlusions may be a useful marker for severe decompensation.

Delayed hypotension and subendocardial injury after repeated umbilical cord occlusion in near-term fetal lambs

OBJECTIVE

This study was undertaken to determine whether myocardial injury occurs after repeated intrauterine asphyxia.

STUDY DESIGN

Near-term fetal sheep with implanted instrumentation underwent either sham occlusions (n = 8) or repeated brief umbilical cord occlusions (n = 12) continued until the onset of severe (<20 mm Hg) or sustained hypotension. After 3 days of recovery, the fetal hearts were perfusion fixed.

RESULTS

Repeated umbilical cord occlusions led to a severe metabolic acidosis (pH, 6.84 +/- 0.09; lactate concentration, 14.1 +/- 1.5 mmol/L) with increasing hypotension during occlusions, which were terminated after 128 +/- 38 minutes. After the occlusions, the mean arterial pressure showed a delayed fall, which resolved after 12 hours. Ultrastructural examination showed evidence of subendocardial injury, with dilatation of sarcoplasmic reticulum, margination and clumping of nuclear chromatin, and mitochondrial swelling. The most severe morphologic changes, including electron-dense mitochondrial inclusions, were found in the fetuses with delayed recovery of the fetal heart rate after the final occlusion.

CONCLUSION

Subendocardial injury occurs after severe repeated intrauterine asphyxia in the late-gestation fetus, and this may contribute to cardiovascular compromise and the development of late decelerations.

A semi-empirical approach to the modeling of the electrophoretic mobility in free solution: application to polystyrenesulfonates of various sulfonation rates

This work focuses on the understanding of the electrophoretic behavior of flexible chains of polystyrenesulfonates (PSSs) in free solution. It deals mainly with the variation of the electrophoretic mobility with (i) the polymerization degree (N) of fully sulfonated PSSs and (ii) the sulfonation rate of randomly sulfonated PSSs. In both cases, the electrophoretic mobility was modeled following a semi-empirical approach which involves parameters retaining a physical meaning. Fully sulfonated PSS oligomers, having a length smaller than or similar to the Debye length, exhibit a particular electrophoretic behavior, in-between that observed for multicharged small molecules and that for polyelectrolytes. The electrophoretic mobility of these oligomers increases strongly with N, which is attributed to a hydrodynamic coupling between monomers. Then the mobility is maximum for an N of about 10, for which the PSS oligomers are still in a rod-like conformation. Afterwards, as N increases and the PSSs are larger than the Debye length, the electrophoretic mobility decreases slowly until it reaches a constant value corresponding to the free-draining behavior. Next, the electrophoretic behavior of long PSS (N about 1,200) differing in their sulfonation rates was investigated. The effective charge rates were determined independently by conductimetric measurements and the mobilities were modeled as a function of the sulfonation rate. The PSS behavior observed was compared to the one previously reported for classical polyelectrolytes having hydrophilic backbones, such as copolymers of poly(acryamide-coacrylic acid). A specific behavior has been pointed out for these partially sulfonated PSSs, which is attributed to the hydrophobicity of their backbone. Finally, it is shown that separations of PSSs of different sulfonation rates can be obtained with electrolytes containing an anionic surfactant or methanol.

Mechanisms of risk in preterm low-birthweight infants

The periodontal diseases share many common risk factors with preterm low birth weight. Examples are, age, socioeconomic status and smoking (Fig. 5). Studies to date have only shown an association between the two conditions, and this does not indicate a causal relationship. However, since the inflammatory mediators that occur in the periodontal diseases, also play an important part in the initiation of labor, there are plausible biological mechanisms that could link the two conditions. The challenge for the future is to characterize the nature of the factors that predispose a mother to give birth prematurely to infants less than 2500 g and to assign relative probabilities to each. Studies are taking place in many parts of the world to determine the probability of a preterm low-birth-weight outcome, the interdependence of the factors that contribute to a birth event and possible casual relationships between these factors. Further information about the details of the effects of maternal infection will come from intervention studies, animal studies and more detailed examination of the mechanisms.

Neuroprotective strategies for basal ganglia degeneration: Parkinson's and Huntington's diseases

There are three main mechanisms of neuronal cell death which may act separately or cooperatively to cause neurodegeneration. This lethal triplet of metabolic compromise, excitotoxicity, and oxidative stress causes neuronal cell death that is both necrotic and apoptotic in nature. Aspects of each of these three mechanisms are believed to play a role in the neurodegeneration that occurs in both Parkinson's and Huntington's diseases. Strategies to rescue or protect injured neurons usually involve promoting neuronal growth and function or interfering with neurotoxic processes. Considerable research has been done on testing a large array of neuroprotective agents using animal models which mimic these disorders. Some of these approaches have progressed to the clinical arena. Here, we review neuroprotective strategies which have been found to successfully ameliorate the neurodegeneration associated with Parkinson's and Huntington's diseases. First, we will give an overview of the mechanisms of cell death and the background of Parkinson's and Huntington's diseases. Then we will elaborate on a range of neuroprotective strategies, including neurotrophic factors, anti-excitotoxins, antioxidants, bioenergetic supplements, anti-apoptotics, immunosuppressants, and cell transplantation techniques. Most of these approaches hold promise as potential therapies in the treatment of these disorders.

Angiotensin II indirectly vasoconstricts the ovine uterine circulation

The uterine vasculature of women and sheep predominantly expresses type 2 ANG II receptors that do not mediate vasoconstriction. Although systemic ANG II infusions increase uterine vascular resistance (UVR), this could reflect indirect mechanisms. Thus we compared systemic and local intra-arterial ANG II infusions in six near-term pregnant and five ovariectomized nonpregnant ewes to determine how ANG II increases UVR. Systemic ANG II dose-dependently (P > 0.001) increased arterial pressure (MAP) and UVR and decreased uterine blood flow (UBF) in pregnant and nonpregnant ewes; however, nonpregnant responses exceeded pregnant (P < 0.001). In contrast, local ANG II infusions at rates designed to achieve concentrations in the uterine circulation comparable to those seen during systemic infusions did not significantly decrease UBF in either group, and changes in MAP and UVR were absent or markedly attenuated. When MAP rose during local ANG II, which only occurred with doses > or =2 ng/ml, increases in MAP were delayed more than twofold compared with responses during systemic ANG II infusions and always preceded decreases in UBF, resembling that observed during systemic ANG II infusions. These observations demonstrate attenuated uterine vascular responses to systemic ANG II during pregnancy and suggest that systemic ANG II may increase UVR through release of another potent vasoconstrictor(s) into the systemic circulation.

Intracerebral transportation and cellular localisation of insulin-like growth factor-1 following central administration to rats with hypoxic-ischemic brain injury

Insulin-like growth factor-1 (IGF-1) has been shown to be neuroprotective when administered centrally following hypoxic-ischemic (HI) brain injury. However, the cerebral distribution and site of action of IGF-1 after intracerebroventricular (i.c.v.) administration are not known. A unilateral HI brain injury was induced in adult rats by a modified Levine method. Either 3H-IGF-1 alone, or in combination with unlabelled IGF-1, was administered into the lateral ventricle 2 h after injury. The activity of 3H-IGF-1 signal in the potentially injured cortex was compared between two treatment groups using image analysis. The regional distribution and cellular localisation of 3H-IGF-1 were examined autoradiographically in potentially injured hemispheres at 0.5 and 6 h after administration. Tritiated IGF-1 was detected predominantly in the pia mater, perivascular spaces and subcortical white matter tracts 0.5 h after administration and decreased by 6 h (p<0.05). The signals associated with the perivascular spaces and pia mater were not blocked by unlabelled IGF-1, suggesting non-saturable binding in these brain areas. IGF-1 signal was co-localised with IGF binding protein (IGFBP)-2 immunostaining in the white matter tracts where the signal was blocked by unlabelled IGF-1, suggesting competitive association. IGF-1 signal associated with neurons and glia was maximal in the cerebral cortex and less in the CA1-2 subregion of the hippocampus which were blocked by unlabelled IGF-1 (p<0.05). The signals from cortical neurons did not decrease 6 h after administration, suggesting specific and persistent binding to these cells. Our results indicate that centrally administered IGF-1 can be translocated to neurons and glia via the perivascular circulation and the ependymal cell-white matter tract pathways.

A role for the somatotropic axis in neural development, injury and disease

This review article discusses the roles of the somatotropic axis in the growth and development of the normal central nervous system (CNS) and during recovery from brain injury. Classically, the actions of pituitary-derived growth hormone (GH) have been reported to be primarily mediated via the induction of hepatic insulin-like growth factor-I (IGF-I). GH receptors (GHRs), however, have now been identified in many body tissues and shown to have both endocrine and local actions, some of which are IGF-I independent. Within the brain, GHRs are widely located across a range of cellular phenotypes, yet little is known regarding their function or endogenous ligand. It is now becoming accepted that GH, like IGF-I, is integrally involved in the growth and development of the normal CNS. Following brain injury, IGF-I mRNA is induced, primarily within reactive microglia. The resultant IGF-I protein appears to have a dual role, first as an endogenous neurotropic and anti-apoptotic agent acting directly on stressed cells, and second as a prohormone for generation of the N-terminal tripeptide of IGF-I, glycine-proline-glutamate (GPE), and the resulting des-N-(1-3)-IGF-I, both of which have specific neuroprotective properties. Our work on deciphering the upstream regulators of injury-induced IGF-I has revealed that a GH-like substance is strongly upregulated after brain injury and specifically associated with stressed neurons and glia. Subsequent to this finding, GH administered centrally 2 hours after a hypoxic-ischemic brain injury in juvenile rats was found to provide significant neuroprotection, interestingly, in a spatiotemporal pattern distinct from the neuroprotection offered by IGF-I. The implications of these findings in regard to the growth, development and injury response of the CNS are discussed.

Role of the cerebrovascular and metabolic responses in the delayed phases of injury after transient cerebral ischemia in fetal sheep

BACKGROUND AND PURPOSE

Perinatal hypoxic-ischemic injuries can trigger a cascade of events leading to delayed deterioration and cell death several hours later. The objective of this study was to characterize the cerebral blood flow responses and the changes in extracellular glucose and lactate during the delayed phases of injury and to determine their relationships with the pathophysiological events after hypoxic-ischemic injury.

METHODS

Two groups of near-term chronically instrumented fetal sheep were subjected to 30 minutes of cerebral hypoperfusion. In the first group, regional cerebral blood flow was measured over the next 24 hours with radiolabeled microspheres. In the second, cortical extracellular glucose and lactate were measured by microdialysis. Parietal electrocorticographic activity and cortical impedance were recorded continuously in both groups, and the extent of neuronal loss was determined histologically at 72 hours after injury.

RESULTS

Cerebral blood flow was transiently impaired in the cortex during reperfusion, whereas during the delayed phase, there was a marked increase in cerebral blood flow. The severity of cortical neuronal loss was related to the degree of hypoperfusion in the immediate reperfusion period and inversely related to the magnitude of the delayed hyperperfusion. Cortical extracellular lactate was elevated after injury, and both glucose and lactate secondarily increased during the delayed phase of injury.

CONCLUSIONS

The delayed phase is accompanied by a period of hyperperfusion that may protect marginally viable tissue.

The IGF-I amino-terminal tripeptide glycine-proline-glutamate (GPE) is neuroprotective to striatum in the quinolinic acid lesion animal model of Huntington's disease

Huntington's disease is an incurable genetic neurological disorder characterized by the relatively selective degeneration of the striatum. Lesioning of the striatum in rodents using the excitatory amino acid agonist, quinolinic acid (QA), effectively mimics the human neuropathology seen in Huntington's disease. Using this animal model of Huntington's disease, we investigated the ability of the insulin-like growth factor-I (IGF-I) amino-terminal tripeptide glycine-proline-glutamate (GPE) to protect striatal neurons from degeneration. Adult rats received a single unilateral intrastriatal injection of QA (100 nmol) and then daily injection of either vehicle or GPE (0.3 microgram/microliter/day) into the striatum for 7 days. QA at this dose resulted in a partial lesioning of the striatum after 7 days to approximately 50% of cells of unlesioned levels in vehicle-treated animals. The major striatal neuronal phenotype, GABAergic projection neurons, were identified by immunocytochemical labeling of either glutamate decarboxylase 67 (GAD(67)) or the calcium binding protein calbindin in alternate sections. Treatment with GPE for 7 days reversed the loss in projection neurons when assessed by counts of calbindin-stained cells; however, these rescued cells did not regain immunologically detectable levels of GAD(67). GPE also significantly reversed the phenotypic degeneration of cholinergic interneurons identified by immunolabeling for choline acetyltransferase (ChAT) and NADPH diaphorase interneurons identified histochemically. GPE treatment failed to rescue the calcium binding protein interneuron populations of parvalbumin and calretinin neurons. These findings reveal that exogenous administration of GPE selectively prevents excitotoxin induced phenotypic degeneration of striatal projection neurons and cholinergic and NADPH diaphorase interneurons in an animal model of Huntington's disease.

Expression of the activin axis and neuronal rescue effects of recombinant activin A following hypoxic-ischemic brain injury in the infant rat

Neurotrophic factors are induced in the brain in response to injury and may restrict the extent of neuronal loss and facilitate recovery. We have previously reported a strong neuronal induction of activin betaA subunit mRNA expression after a hypoxic-ischemic (HI) injury in the rat brain. Here, we further extended our studies to examine a role for the activin inhibitory binding protein, follistatin after injury and also to determine the potential of activin as a neuronal rescue agent. Ribonuclease protection assay (RPA) was used to quantify the time course of the mRNA expression of activin betaA subunit and follistatin, following a 60-min HI brain injury. Activin betaA subunit mRNA level increased in the contralateral hemisphere 5 h after injury and returned to normal at 10 h post injury. In contrast, follistatin mRNA levels decreased in the same hemisphere at 5 and 10 h after injury. The effect of intracerebroventrically (i. c.v.) administered recombinant human activin A or its antagonist, inhibin A, on neuronal death after a 15-min HI brain injury was determined for a number of brain regions. One microgram activin A (n=23) reduced the neuronal loss in the hippocampal CA1/2 region, dorsolateral striatum but not in the parietal cortex. In contrast, 1 microg of inhibin A (n=18) did not have a significant effect on the extent of neuronal loss in any of the affected regions. This pattern of neuroprotection was consistent with the distribution of immunoreactivity for the activin receptor type II subunit. These results demonstrate that activin A, but not its functional antagonist inhibin A, can enhance the survival of injured hippocampal and striatal neurons. Since follistatin is thought to exert a neutralising effect on activin A activity, the down-regulation of follistatin expression post injury may be allowing activin A to become more accessible to neurons after injury. Overall, these results suggest a role of the activin axis in modulating the survival of specific populations of injured neurons.

Administration of recombinant human Activin-A has powerful neurotrophic effects on select striatal phenotypes in the quinolinic acid lesion model of Huntington's disease

Huntington disease is characterized by the selective loss of striatal neurons, particularly of medium-sized spiny glutamate decarboxylase67 staining/GABAergic projection neurons which co-contain the calcium binding protein calbindin. Lesioning of the adult rat striatum by intrastriatal injection of the N-methyl-D-aspartate receptor agonist quinolinic acid (100 nmol) results in a pattern of striatal neuropathology seven days later that resembles that seen in the Huntington brain. Using this animal model of human Huntington's disease we investigated the effect of daily intrastriatal infusion of the nerve cell survival molecule ActivinA (single bolus dose of 0.73 microg daily for seven days) on the quinolinic acid-induced degeneration of various striatal neuronal phenotypes. By seven days, unilateral intrastriatal infusion of quinolinic acid produced a partial but significant loss (P < 0.01) in the number of striatal neurons immunoreactive for glutamate decarboxylase (to 51.0+/-5.8% of unlesioned levels), calbindin (to 58.7+/-5.1%), choline acetyltransferase (to 68.6+/-6.1%), NADPH-diaphorase (to 47.4+/-5.4%), parvalbumin (to 58.8+/-4.1%) and calretinin (to 60.6+/-8.6%) in adult rats that were administered intrastriatal phosphate-buffered saline for seven days following quinolinic acid. In contrast, in rats that received intrastriatal recombinant human ActivinA once daily for seven days following quinolinic acid, phenotypic degeneration was significantly attenuated in several populations of striatal neurons. Treatment with ActivinA had the most potent protective effect on the striatal cholinergic interneuron population almost completely preventing the lesion induced decline in choline acetyltransferase expression (to 95.1+/-5.8% of unlesioned levels, P < 0.01). ActivinA also conferred a significant protective effect on parvalbumin (to 87.5+/-7.7%, P < 0.01) and NADPH-diaphorase (to 77.5+/-7.5%, P < 0.01) interneuron populations but failed to prevent the phenotypic degeneration of calretinin neurons (to 56.6+/-5.5%). Glutamate decarboxylase67 and calbindin-staining nerve cells represent largely overlapping populations and both identify striatal GABAergic projection neurons. We found that ActivinA significantly attenuated the loss in the numbers of neurons staining for calbindin (to 79.7+/-6.6%, P < 0.05) but not glutamate decarboxylase67 (to 61.1+/-5.9%) at seven days following quinolinic acid lesioning. Taken together these results suggest that exogenous administration of ActivinA can rescue both striatal interneurons (labelled with choline acetyltransferase, parvalbumin, NADPH-diaphorase) and striatal projection neurons (labelled by calbindin) from excitotoxic lesioning with quinolinic acid. Longer-term studies will be required to determine whether these surviving calbindin-expressing projection neurons recover their ability to express the glutamate decarboxylase67/GABAergic phenotype. These results therefore suggest that treatment with ActivinA may help to prevent the degeneration of vulnerable striatal neuronal populations in Huntington's disease.

Nitric oxide synthase inhibition and delayed cerebral injury after severe cerebral ischemia in fetal sheep

After transient cerebral ischemia in fetal sheep, delayed disruptions in cerebral energetics are represented by a delayed increase in cortical impedance, a progressive decrease in the concentration of oxidized cytochrome oxidase as measured by near-infrared spectroscopy, and cortical seizures. Because the production of nitric oxide (NO), a potent mediator of neuronal death, is increased during this phase, the present study investigated whether inhibition of NO synthesis could ameliorate the delayed disruption in cerebral energetics. Eleven late gestation fetal sheep were subjected to 30 min of transient cerebral ischemia in utero. Two hours later, the treatment group (n = 5) received a continuous infusion of N(G)-nitro-L-arginine, a competitive inhibitor of NO synthase, whereas the control group (n = 6) received PBS. Changes in concentration of oxidized cytochrome oxidase, cortical impedance, and electrocortical activity were observed for 3 d. A delayed increase in cortical impedance of similar magnitude and duration commenced at 14+/-4 h in the control and at 15+/-3 h in the treatment groups. The progressive decrease in oxidized cytochrome oxidase signal, by -2.2+/-0.2 micromol/L in the control and -2.0+/-0.4 micromol/L in the treatment group at 72 h postischemia, was similar in both groups. In both groups, delayed cortical seizures were indicated by intense low-frequency electrocortical activity. In the treatment group, duration of cortical seizures was increased and the intensity of the final electrocortical activity was more depressed (-19+/-1 dB versus -10+/-2 dB). The results indicate that after cerebral ischemia in fetal sheep, NO synthase inhibition does not ameliorate the delayed disruptions in cerebral energetics. However, the effect of NO synthase inhibition on delayed cortical seizures may improve our understanding of the role of NO during this phase.

Crystallization and preliminary X-ray studies on the molbindin ModG from Azotobacter vinelandii

Crystals of the molbindin ModG (subunit Mr = 14359 Da), a cytoplasmic molybdate-binding protein from Azotobacter vinelandii, were grown by vapour diffusion. Both apo and tungstate-bound forms were crystallized and X-ray data were collected at 100 K. Apo-ModG crystallizes in space group P6322, with unit-cell dimensions a = b = 90.62, c = 79.46 A. Native data to a resolution of 2.5 A were collected from a single crystal, which showed a marked improvement in diffraction quality after annealing. Data from a single-site gold derivative were also collected at 2.7 A resolution. Crystals of the ligand-bound form of ModG belong to space group P321, with unit-cell parameters a = b = 50.57, c = 79.29 A. X-ray data to a resolution of 2.0 A were collected.

Alterations in the neural growth hormone axis following hypoxic-ischemic brain injury

Recently, there has been considerable interest in determining the role of the growth hormone receptor (GHR) in the central nervous system (CNS). The aim of this study was to investigate the role of circulating growth hormone (GH) and the neural GHR after hypoxic-ischemic (HI) brain injury in the 21-day old rat. We observed growth hormone receptor/binding protein (GHR/BP) immunoreactivity to be rapidly upregulated following a severe unilateral HI injury. There was a biphasic increase with an initial rise occurring in blood vessels within a few hours after injury followed by a secondary rise evident by 3 days post-hypoxia in microglia/macrophages, some of which are destined to express insulin-like growth factor-I (IGF-I). There was also an increased immunoreactivity in reactive astrocytes, some of which were in the process of dividing. Subsequently, we attempted to activate the endothelial GHR/BP which was found to be increased after injury by treating with 15 microgram g-1 day-1 s.c. bGH for 7 days. Circulating concentrations of IGF-I fell after injury and were restored with GH treatment (P=0.001), whereas treatment of normal animals had no effect on serum IGF-I. Peripheral GH treatment increased the cerebrospinal fluid (CSF) concentration of immunoreactive IGF-I in the injured rats (P=0.017). GH treatment also reversed the systemic catabolism caused by the injury but had no significant neuroprotective effects. These results indicate that GH therapy can be used to reverse the systemic catabolism that occurs after CNS injury. In addition, these data suggest a role for the neural GHR during the recovery from brain injury, both in terms of the induction of IGF-I and in terms of glial proliferation.

Melanocortin-4 receptor messenger RNA expression is up-regulated in the non-damaged striatum following unilateral hypoxic-ischaemic brain injury

Melanocortin peptides (alpha-melanocyte-stimulating hormone, adrenocorticotropin and fragments thereof) have been shown to have numerous effects on the central nervous system, including recovery from nerve injury and retention of learned behaviour, but the mechanism of action of these peptides is unknown. A family of five melanocortin receptors have recently been discovered, two of which (melanocortin-3 and melanocortin-4 receptors) have been mapped in the rat brain. We have tested the hypothesis that the expression of one or more of the messenger RNAs for three melanocortin receptors (melanocortin-3, melanocortin-4 and melanocortin-5 receptors) would be altered in rat brain following unilateral transient hypoxic-ischaemic brain injury. In this study, using in situ hybridization, we show that melanocortin-4 receptor messenger RNA was up-regulated in the striatum in the non-damaged hemisphere within 24 h after severe hypoxic-ischaemic injury compared with control brains (P<0.05). In a small group of animals, this induction was not blocked by treatment with the anticonvulsant, carbamazepine. Expression of melanocortin-3 receptor messenger RNA in the brain was not altered in this hypoxic-ischaemic injury model and melanocortin-5 receptor messenger RNA was not detected in either control or hypoxic-ischaemic injured rat brains. We hypothesize that the up-regulation of melanocortin-4 receptor messenger RNA expression in the contralateral striatum may be involved in transfer of function to the uninjured hemisphere following unilateral brain injury.

The effects of the N-terminal tripeptide of insulin-like growth factor-1, glycine-proline-glutamate in different regions following hypoxic-ischemic brain injury in adult rats

Insulin-like growth factor-1 has pleiotropic effects in the central nervous system and can act both as a survival and a differentiation factor. Insulin-like growth factor-1 can be proteolytically cleaved into des-N-(1-3)-insulin-like growth factor-1 and a N-terminal tripeptide fragment, glycine-proline-glutamate. Both insulin-like growth factor-1 and des-N-(1-3)-insulin-like growth factor-1 can improve neuronal survival after hypoxic-ischemic brain injury in vivo. The present study investigates the effects of glycine-proline-glutamate on different brain regions and neuronal populations after hypoxic-ischemic injury. Unilateral hypoxic-ischemic injury was induced in adult rats. Glycine-proline-glutamate (3 microg) was administered centrally 2 h after the injury and the extent of brain damage determined five days later. In a separate trial immunohistochemical techniques were used to determine the effects of glycine-proline-glutamate on specific populations of neurons in the striatum after the injury. Compared to the vehicle treatment, glycine-proline-glutamate (n=19) treatment reduced the extent of cortical damage and neuronal loss in the CA1-2 subregions of the hippocampus (P<0.05). In the striatum, there was a trend towards a reduction in neuronal loss after glycine-proline-glutamate treatment (P=0.053) compared to the vehicle (n=21)-treated animals. In a separate study, glycine-proline-glutamate (n=8) treatment prevented the loss of choline acetyltransferase (P<0.05), glutamate acid decarboxylase (P<0.05) and somatostatin (P<0.05) containing neurons in the ipsilateral striatum following hypoxic-ischemic brain injury and also increased the numbers of neuronal nitric oxide synthase (P<0.05) containing neurons in the contralateral side. These studies suggest that in addition to neuroprotective effects, glycine-proline-glutamate can influence neuronal activity after hypoxic-ischemic injury.

Activity and injury-dependent expression of inducible transcription factors, growth factors and apoptosis-related genes within the central nervous system

This review primarily discusses work that has been performed in our laboratories and that of our direct collaborators and therefore does not represent an exhaustive review of the current literature. Our aim is to further discuss the role that gene expression plays in neuronal plasticity and pathology. In the first part of this review we examine activity-dependent changes in the expression of inducible transcription factors (ITFs) and neurotrophins with long-term potentiation (LTP) and kindling. This work has identified particular ITFs (Krox-20 and Krox-24) and neurotrophin systems (particularly the brain-derived neurotrophic factor (BDNF)/tyrosine receptor kinase-B, Trk-B system) that may be involved in stabilizing long-lasting LTP (i.e. LTP3). We also show that changes in the expression of other ITFs (Fos, Jun-D and Krox-20) and the BDNF/trkB neurotrophin system may play a central role in the development of hippocampal kindling, an animal model of human temporal lobe epilepsy. In the next part of this review we examine changes in gene expression after neuronal injuries (ischemia, prolonged seizure activity and focal brain injury) and after nerve transection (axotomy). We identify apoptosis-related genes (p53, c-Jun, Bax) whose delayed expression selectively increases in degenerating neurons, further suggesting that some forms of neuronal death may involve apoptosis. Moreover, since overexpression of the tumour-suppressor gene p53 induces apoptosis in a wide variety of dividing cell types we speculate that it may perform the same function in post-mitotic neurons following brain injuries. Additionally, we show that neuronal injury is associated with rapid, transient, activity-dependent expression of neurotrophins (BDNF and activinA) in neurons, contrasting with a delayed and more persistent injury-induced expression of certain growth factors (IGF-1 and TGFbeta) in glia. In this section we also describe results linking ITFs and neurotrophic factor expression. Firstly, we show that while BDNF and trkB are induced as immediate-early genes following injury, the injury-induced expression of activinA and trkC may be regulated by ITFs. We also discuss whether loss of retrograde transport of neurotrophic factors such as nerve growth factor following nerve transection triggers the selective and prolonged expression of c-Jun in axotomized neurons and whether c-Jun is responsible for regeneration or degeneration of these axotomized neurons. In the last section we further examine the role that gene expression may play in memory formation, epileptogenesis and neuronal degeneration, lastly speculating whether the expression of various growth factors after brain injury represents an endogenous neuroprotective response of the brain to injury. Here we discuss our results which show that pharmacological enhancement of this response with exogenous application of IGF-1 or TGF-beta reduces neuronal loss after brain injury.

Neuroprotective effects of Gly-Pro-Glu, the N-terminal tripeptide of IGF-1, in the hippocampus in vitro

Insulin-like growth factor 1 (IGF-1) plays a critical role in CNS development. IGF-1 can block neuronal apoptosis in vitro and in vivo. IGF-1 is thought to be cleaved into des-N-(1-3)-IGF-1 and an amino terminal glycine-proline-glutamate (GPE tripeptide). Here we report a neuroprotective role for GPE tripeptide, with enhanced survival of the CA1-2 hippocampal neurons following an excitotoxic insult in vitro. Binding and displacement studies suggest uniquely distributed sites of action within the rat including the hippocampal CA1-2, pyriform cortex, amygdala, choroid plexus, blood vessels and to a lesser extent in the cortical regions. A similar pattern of binding was seen in the human. This finding could lead to new strategies to reduce neuronal death after injury and in disease.

Ligand size is a major determinant of specificity in periplasmic oxyanion-binding proteins: the 1.2 A resolution crystal structure of Azotobacter vinelandii ModA

BACKGROUND

. Periplasmic receptors constitute a diverse class of binding proteins that differ widely in size, sequence and ligand specificity. Nevertheless, almost all of them display a common beta/alpha folding motif and have similar tertiary structures consisting of two globular domains. The ligand is bound at the bottom of a deep cleft, which lies at the interface between these two domains. The oxyanion-binding proteins are notable in that they can discriminate between very similar ligands.

RESULTS

. Azotobacter vinelandii is unusual in that it possesses two periplasmic molybdate-binding proteins. The crystal structure of one of these with bound ligand has been determined at 1.2 A resolution. It superficially resembles the structure of sulphate-binding protein (SBP) from Salmonella typhimurium and uses a similar constellation of hydrogen-bonding interactions to bind its ligand. However, the detailed interactions are distinct from those of SBP and the more closely related molybdate-binding protein of Escherichia coli.

CONCLUSIONS

. Despite differences in the residues involved in binding, the volumes of the binding pockets in the A. vinelandii and E. coli molybdate-binding proteins are similar and are significantly larger than that of SBP. We conclude that the discrimination between molybdate and sulphate shown by these binding proteins is largely dependent upon small differences in the sizes of these two oxyanions.