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.

Log D versus HPLC derived hydrophobicity: The development of predictive tools to aid in the rational design of bioactive peptoids.

Hydrophobicity has proven to be an extremely useful parameter in small molecule drug discovery programmes given that it can be used as a predictive tool to enable rational design. For larger molecules, including peptoids, where folding is possible, the situation is more complicated and the average hydrophobicity (as determined by RP-HPLC retention time) may not always provide an effective predictive tool for rational design. Herein, we report the first ever application of partitioning experiments to determine the log D values for a series of peptoids. By comparing log D and average hydrophobicities we highlight the potential advantage of employing the former as a predictive tool in the rational design of biologically active peptoids.

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.

Transverse vaginal septae: management and long-term outcomes.

OBJECTIVE: To examine the management and long-term outcomes of transverse vaginal septae. DESIGN: Observational study with cross-sectional and retrospective arms. SETTING: Tertiary referral centre specialising in Müllerian anomalies. POPULATION: Forty-six girls and women with a transverse vaginal septum. METHODS: Data from medical records of all cases (1998-2013) of transverse vaginal septae were collected and reviewed. Patients over 16 years of age also completed a questionnaire. MAIN OUTCOME MEASURES: Presentation, examination findings, investigations, surgery, and long-term reproductive outcomes. RESULTS: The septae in the study were described as follows: 61% (95% CI 0.46-0.74) were imperforate, and presented with obstructed menstruation; 39% (95% CI 0.26-0.54) were perforate, and presented with a variety of concerns; 72% (95% CI 0.57-0.83) were low, 22% (95% CI 0.12-0.36) were mid-vaginal, and 6% (95% CI 0.02-0.18) were high; 33% were managed via an abdominoperineal approach, 59% were managed via a vaginal approach, and 6% had laparoscopic resection (one patient did not have surgery); 11% (95% CI 0.05-0.23) of patients presented with reobstruction, all following abdominoperineal vaginoplasty; 7% presented with vaginal stenosis, two following vaginal resection and one following the abdominoperineal approach; 61% of questionnaires were returned. These results showed that 22/23 patients were menstruating and one had a hysterectomy, 74% had been sexually active, 35% had dyspareunia, and 36% complained of dysmenorrhoea. There were seven pregnancies, with one termination and six live births, all following the vaginal excision of a transverse vaginal septum. CONCLUSIONS: Transverse vaginal septae resected vaginally or laparoscopically have low complication rates and good long-term outcomes. Complex septae require more extensive surgery, with an increased risk of complications.

Transoral laser resection versus lip-split mandibulotomy in the management of oropharyngeal squamous cell carcinoma (OPSCC): a case match study.

The objective of this study was to compare transoral laser microsurgery (TLM) with lip-split mandibulotomy (LSM) and radial forearm free-flap reconstruction, for the resection of squamous cell carcinoma of the oropharynx (SCCOP). This study is designed as a case-control study matching 24 patients treated with TLM for SCCOP with those treated with LSM. Patients were matched by age (in 5-year epochs), sex, TNM stage, tumour sub site and type of neck dissection. Each group comprised 20 males and 4 females (mean age 56 years). Seven patients treated with TLM had an elective tracheostomy compared with all patients undergoing LSM. Moreover, the time for decanulation was reduced in patients undergoing tracheostomy for TLM. Although similar rates of patients were able to swallow to some degree on discharge, 29% of patients having LSM were discharged requiring enterostomy feeding compared with 4% of patients treated using TLM. Of those able to swallow on discharge, patients who had TLM resumed swallowing in half the time taken for those having LSM. Moreover, those treated with TLM remained in hospital for half the length of time than those treated with LSM. Due to these factors, overall cost for TLM is reduced in comparison with LSM. In comparison with LSM, TLM for the treatment of SCCOP results in fewer tracheostomies and shorter time to decanulation; a quicker recovery of swallowing function and a reduced length of hospital stay. As a result of this, treatment with TLM is on average cheaper. These factors should be considered when deciding on the surgical treatment of a patient with SCCOP.

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.

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.

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.

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.

Dietary Intake, Attitudes toward Healthy Food, and Dental Pain in Low-Income Youth.

Few studies have examined the relation between food consumption and related attitudes and dental pain among children. The objective of this study is to examine the associations of healthy and unhealthy food items, attitudes toward healthy food, and self-efficacy of eating healthy with dental pain among children. A cross-sectional analysis was performed using child survey data from the Texas Childhood Obesity Research Demonstration (TX CORD) project. Fifth-grade students ( n = 1,020) attending 33 elementary schools in Austin and Houston, Texas, completed the TX CORD Child Survey, a reliable and valid survey instrument focused on nutrition and physical activity behaviors. All nutrition questions ask about the number of times food and beverage items were consumed on the previous day. Dental pain was reported as mouth or tooth pain in the past 2 wk that made their mouth hurt so much that they could not sleep at night. Mixed-effects logistic regression models were used to test the association between 10 unhealthy food items, 9 healthy food items, 2 health attitudes, and self-efficacy with dental pain. All models controlled for sociodemographic variables. In total, 99 (9.7%) students reported dental pain. Dental pain was associated with intake of the following unhealthy items: soda, fruit juice, diet soda, frozen desserts, sweet rolls, candy, white rice/pasta, starchy vegetables, French fries/chips, and cereal (adjusted odds ratio [AOR], 1.27-1.81, P < 0.01). The intake of other vegetables (AOR, 1.56; P < 0.01), a healthy item, and the attitude that healthy food tastes good (AOR, 1.59; P = 0.04) were also positively associated with dental pain. The attitude of eating healthier leads to fewer health problems (AOR, 0.50) and self-efficacy for healthy eating (AOR, 0.44) were negatively associated with dental pain ( P < 0.01). Interventions should focus on improving oral health by reducing intake of unhealthy foods and educating children and families on the importance of diet as a means of reducing dental caries. Knowledge Transfer Statement: The results of this study can be used to inform researchers on potential food items and psychosocial measures to examine in low-income, minority populations for longitudinal research. These results would also be useful to educators who could incorporate oral health care and nutrition education into school curriculums.

Insulin-like growth factor-1 is a potent neuronal rescue agent after hypoxic-ischemic injury in fetal lambs.

This study was designed to determine the potential of IGF-1 as a neuronal rescue agent after cerebral ischemia. Unanesthetized late gestation fetal sheep were subjected to 30-min cerebral ischemia by inflation of carotid artery occluder cuffs. 2 h later either 0.1 microgram rhIGF-1, 1 microgram rhIGF-1, 10 micrograms rhIGF-1, or vehicle was infused into a lateral cerebral ventricle over 1 h. Histologic outcome was assessed 5 d later. Overall neuronal loss was reduced with 0.1 microgram (P < 0.05) and 1 microgram (P < 0.002) rhIGF-1, but treatment with 10 micrograms was not effective. With 1 microgram rhIGF-1 neuronal loss scores were significantly lower in brain regions examined including cortex, hippocampus, and striatum, whereas with 0.1 microgram rhIGF-1 the parietal cortex and thalamus were not improved and the improvement seen in other regions was less than with 1 microgram rhIGF-1. Treatment with 1 microgram rhIGF-1 also delayed the onset of seizures and reduced their incidence. Moreover, the secondary phase of cytotoxic edema was reduced and delayed in onset. We conclude that low dose rhIGF-1 therapy promotes neuronal rescue after cerebral hypoxic-ischemic injury in utero, but the effect is dose dependent. Importantly, rhIGF-1 is effective and nontoxic when administered 2 h after the hypoxic ischemic insult. This distinguishes IGF-1 from most other neuroprotective therapies and suggests clinical application may be possible.

Dramatic neuronal rescue with prolonged selective head cooling after ischemia in fetal lambs.

Hypothermia has been proposed as a neuroprotective strategy. However, short-term cooling after hypoxia-ischemia is effective only if started immediately during resuscitation. The aim of this study was to determine whether prolonged head cooling, delayed into the late postinsult period, improves outcome from severe ischemia. Unanesthetized near term fetal sheep were subject to 30 min of cerebral ischemia. 90 min later they were randomized to either cooling (n = 9) or sham cooling (n = 7) for 72 h. Intrauterine cooling was induced by a coil around the fetal head, leading initially to a fall in extradural temperature of 5-10 degrees C, and a fall in esophageal temperature of 1.5-3 degrees C. Cooling was associated with mild transient systemic metabolic effects, but not with hypotension or altered fetal heart rate. Cerebral cooling reduced secondary cortical cytotoxic edema (P < 0.001). After 5 d of recovery there was greater residual electroencephalogram activity (-5.2+/-1.6 vs. -15.5+/-1.5 dB, P < 0.001) and a dramatic reduction in the extent of cortical infarction and neuronal loss in all regions assessed (e.g., 40 vs. 99% in the parasagittal cortex, P < 0.001). Selective head cooling, maintained throughout the secondary phase of injury, is noninvasive and safe and shows potential for improving neonatal outcome after perinatal asphyxia.

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.

Ring and peg electrodes for minimally-Invasive and long-term sub-scalp EEG recordings.

OBJECTIVE: Minimally-invasive approaches are needed for long-term reliable Electroencephalography (EEG) recordings to assist with epilepsy diagnosis, investigation and more naturalistic monitoring. This study compared three methods for long-term implantation of sub-scalp EEG electrodes. METHODS: Three types of electrodes (disk, ring, and peg) were fabricated from biocompatible materials and implanted under the scalp in five ambulatory ewes for 3months. Disk electrodes were inserted into sub-pericranial pockets. Ring electrodes were tunneled under the scalp. Peg electrodes were inserted into the skull, close to the dura. EEG was continuously monitored wirelessly. High resolution CT imaging, histopathology, and impedance measurements were used to assess the status of the electrodes at the end of the study. RESULTS: EEG amplitude was larger in the peg compared with the disk and ring electrodes (p<0.05). Similarly, chewing artifacts were lower in the peg electrodes (p<0.05). Electrode impedance increased after long-term implantation particularly for those within the bone (p<0.01). Micro-CT scans indicated that all electrodes stayed within the sub-scalp layers. All pegs remained within the burr holes as implanted with no evidence of extrusion. Eight of 10 disks partially eroded into the bone by 1.0mm from the surface of the skull. The ring arrays remained within the sub-scalp layers close to implantation site. Histology revealed that the electrodes were encapsulated in a thin fibrous tissue adjacent to the pericranium. Overlying this was a loose connective layer and scalp. Erosion into the bone occurred under the rim of the sub-pericranial disk electrodes. CONCLUSIONS: The results indicate that the peg electrodes provided high quality EEG, mechanical stability, and lower chewing artifact. Whereas, ring electrode arrays tunneled under the scalp enable minimal surgical techniques to be used for implantation and removal.

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.

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.

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.

RFLP analysis of chromosomal segregation in progeny from an interspecific hexaploid somatic hybrid between Solanum brevidens and Solanum tuberosum.

Segregation of restriction fragment length polymorphism (RFLP) loci was monitored to determine the degree of homeologous pairing and recombination in a hexaploid somatic hybrid, A206, the result of protoplast fusion between Solanum tuberosum (PI 203900, a tetraploid cultivated potato) and Solanum brevidens (PI 218228), a diploid, sexually incompatible, distant relative harboring several traits for disease resistance. Somatic hybrid A206 was crossed to Katahdin, a tetraploid potato cultivar, to generate a segregating population of pentaploid progeny. Although the clones of the tetraploid S. tuberosum lines PI 203900 and Katahdin were highly polymorphic, the diploid S. brevidens clone was homozygous at all but two of the tested RFLP loci. Thus, homeologous recombination could be detected only when S. tuberosum and S. brevidens chromosomes paired and the S. brevidens homologs then segregated into separate gametes. A bias toward homologous pairing was observed for all 12 chromosomes. At least four and perhaps six chromosomes participated in homologous pairing only; each of 24 progeny contained all S. brevidens-derived RFLP markers for chromosomes 4, 8, 9 and 10. The remaining six chromosomes paired with their homolog(s) about twice as often as expected if hexaploid pairings were completely random. Where detectable with RFLPs, homeologous recombination (both single and double) occurred at a frequency of 1.31 per chromosome. Cytological observations of meiosis I in the somatic hybrid indicated that homeologous pairing had occurred. Enhanced recombinational activity was observed for chromosome 2. A specific small deletion from chromosome 4 was detected in A206 and 11 other somatic hybrids out of 14 screened.(ABSTRACT TRUNCATED AT 250 WORDS)