Cell-specific and developmental expression of lectican-cleaving proteases in mouse hippocampus and neocortex.

Mounting evidence has demonstrated that a specialized extracellular matrix exists in the mammalian brain and that this glycoprotein-rich matrix contributes to many aspects of brain development and function. The most prominent supramolecular assemblies of these extracellular matrix glycoproteins are perineuronal nets, specialized lattice-like structures that surround the cell bodies and proximal neurites of select classes of interneurons. Perineuronal nets are composed of lecticans, a family of chondroitin sulfate proteoglycans that includes aggrecan, brevican, neurocan, and versican. These lattice-like structures emerge late in postnatal brain development, coinciding with the ending of critical periods of brain development. Despite our knowledge of the presence of lecticans in perineuronal nets and their importance in regulating synaptic plasticity, we know little about the development or distribution of the extracellular proteases that are responsible for their cleavage and turnover. A subset of a large family of extracellular proteases (called a disintegrin and metalloproteinase with thrombospondin motifs [ADAMTS]) is responsible for endogenously cleaving lecticans. We therefore explored the expression pattern of two aggrecan-degrading ADAMTS family members, ADAMTS15 and ADAMTS4, in the hippocampus and neocortex. Here, we show that both lectican-degrading metalloproteases are present in these brain regions and that each exhibits a distinct temporal and spatial expression pattern. Adamts15 mRNA is expressed exclusively by parvalbumin-expressing interneurons during synaptogenesis, whereas Adamts4 mRNA is exclusively generated by telencephalic oligodendrocytes during myelination. Thus, ADAMTS15 and ADAMTS4 not only exhibit unique cellular expression patterns but their developmental upregulation by these cell types coincides with critical aspects of neural development.

Phthalates and critically ill neonates: device-related exposures and non-endocrine toxic risks.

OBJECTIVE: To assess the types and magnitudes of non-endocrine toxic risks to neonates associated with medical device-related exposures to di(2-ethylhexyl)phthalate (DEHP). STUDY DESIGN: Dose-response thresholds for DEHP toxicities were determined from published data, as were the magnitudes of DEHP exposures resulting from neonatal contact with polyvinyl chloride (PVC) devices. Standard methods of risk assessment were used to determine safe levels of DEHP exposure in neonates, and hazard quotients were calculated for devices individually and in aggregate. RESULT: Daily intake of DEHP for critically ill preterm infants can reach 16 mg/kg per day, which is on the order of 4000 and 160,000 times higher than desired to avoid reproductive and hepatic toxicities, respectively. The non-endocrine toxicities of DEHP are similar to complications experienced by preterm neonates. CONCLUSION: DEHP exposures in neonatal intensive care are much higher than estimated safe limits, and might contribute to common early and chronic complications of prematurity. Concerns about phthalates should be expanded beyond endocrine disruption.

Functional characterization of tissue inhibitor of metalloproteinase-1 (TIMP-1) N- and C-terminal domains during Xenopus laevis development.

Extracellular matrix (ECM) remodeling is essential for facilitating developmental processes. ECM remodeling, accomplished by matrix metalloproteinases (MMPs), is regulated by endogenous tissue inhibitors of metalloproteinases (TIMPs). While the TIMP N-terminal domain is involved in inhibition of MMP activity, the C-terminal domain exhibits cell-signaling activity, which is TIMP and cell type dependent. We have previously examined the distinct roles of the Xenopus laevis TIMP-2 and -3 C-terminal domains during development and here examined the unique roles of TIMP-1 N- and C-terminal domains in early X. laevis embryos. mRNA microinjection was used to overexpress full-length TIMP-1 or its individual N- or C-terminal domains in embryos. Full-length and C-terminal TIMP-1 resulted in increased lethality compared to N-terminal TIMP-1. Overexpression of C-terminal TIMP-1 resulted in significant decreases in mRNA levels of proteolytic genes including TIMP-2, RECK, MMP-2, and MMP-9, corresponding to decreases in MMP-2 and -9 protein levels, as well as decreased MMP-2 and MMP-9 activities. These trends were not observed with the N-terminus. Our research suggests that the individual domains of TIMP-1 are capable of playing distinct roles in regulating the ECM proteolytic network during development and that the unique functions of these domains are moderated in the endogenous full-length TIMP-1 molecule.

Mutations in monoamine oxidase (MAO) genes in mice lead to hypersensitivity to serotonin-enhancing drugs: implications for drug side effects in humans.

A possible side effect of serotonin-enhancing drugs is the serotonin syndrome, which can be lethal. Here we examined possible hypersensitivity to two such drugs, the serotonin precursor 5-hydroxy-L-tryptophan (5-HTP) and the atypical opioid tramadol, in mice lacking the genes for both monoamine oxidase A (MAOA) and MAOB. MAOA/B-knockout (KO) mice displayed baseline serotonin syndrome behaviors, and these behavioral responses were highly exaggerated following 5-HTP or tramadol versus baseline and wild-type (WT) littermates. Compared with MAOA/B-WT mice, baseline tissue serotonin levels were increased ∼2.6-3.9-fold in MAOA/B-KO mice. Following 5-HTP, serotonin levels were further increased ∼4.5-6.2-fold in MAOA/B-KO mice. These exaggerated responses are in line with the exaggerated responses following serotonin-enhancing drugs that we previously observed in mice lacking the serotonin transporter (SERT). These findings provide a second genetic mouse model suggestive of possible human vulnerability to the serotonin syndrome in individuals with lesser-expressing MAO or SERT polymorphisms that confer serotonergic system changes.

Domain specific overexpression of TIMP-2 and TIMP-3 reveals MMP-independent functions of TIMPs during Xenopus laevis development.

Extracellular matrix remodelling mediates many processes including cell migration and differentiation and is regulated through the enzymatic action of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs). TIMPs are secreted proteins, consisting of structurally and functionally distinct N- and C-terminal domains. TIMP N-terminal domains inhibit MMP activity, whereas their C-terminal domains may have cell signalling activity. The in vivo role of TIMP N- and C-terminal domains in regulating developmental events has not previously been demonstrated. Here we investigated the roles of TIMP-2 and TIMP-3 N- and C-terminal domains in Xenopus laevis embryos. We show that overexpression of TIMP-2 N- and C-terminal domains results in severe developmental defects and death, as well as unique changes in MMP-2 and -9 expression, indicating that the individual domains may regulate MMPs through distinct mechanisms. In contrast, we show that only the N-terminal, but not the C-terminal domain of TIMP-3, results in developmental defects.

Falls in older people - an overview for the acute physician.

Falls are common amongst older adults inflicting a substantial socioeconomic burden. Aetiology is often multifactorial. Comprehensive individualised assessment is pivotal to direct effective interventions. We provide an overview of falls and highlight an approach for acute physicians who will increasingly encounter this mode of presentation in an ageing population.

Balloon tamponade for variceal haemorrhage: a practical approach.

Balloon tamponade with compression tubes is used to stabilise life-threatening variceal bleeds when first-line endotherapy has failed and acts as a bridge to early definitive therapy. We present an overview of the use of compression tubes for variceal haemorrhage with a focus on insertion technique and aftercare.

Budd-Chiari syndrome--a review of the diagnosis and management.

Budd-Chiari syndrome (BCS) is the liver disease resulting from hepatic venous outflow obstruction comprising a triad of abdominal discomfort, hepatomegaly and ascites. Advances in the management of this disorder over the last three decades have dramatically improved survival. We present a review of the management of BCS followed by a case which illustrates some key points in the diagnosis and treatment of this condition.

Imaging evaluation of intrathecal baclofen pump-catheter systems.

ITB pumps are widely used in the treatment of intractable spasticity for many clinical indications, including cerebral palsy and spinal cord injury. High-dose intrathecal administration places the patient at significant risk for withdrawal in the event of device malfunction, necessitating rapid and complete evaluation of the pump-catheter system. This article reviews the approach to imaging evaluation of ITB pump-catheter systems, with specific emphasis on radiography, fluoroscopy, CT, and nuclear scintigraphy.

A carpet-based mechanism for direct antimicrobial peptide activity against vaccinia virus membranes.

Antimicrobial peptides have activity against a wide variety of biological membranes and are an important component of innate immunity in vertebrate as well as invertebrate systems. The mechanisms of action of these peptides are incompletely understood and a number of competing but not necessarily mutually exclusive models exist. In this study we examined the virucidal activity of four peptides, the human cathelicidin derived LL37, Xenopus alanine-substituted Magainin-2 amide, uperin-3.1, and a cecropin-LL37 hybrid against vaccinia virus. The peptides were shown to be differentially virucidal but all were shown to attack the viral envelope, with LL37 being the most effective and uperin-3.1 the least. Density gradient analysis of the treated virions indicated the virus outer membrane was efficiently removed by peptide action and suggests a mechanism of direct virus inactivation that is consistent with the carpet model for peptide-mediated membrane disruption. Interestingly, the least effective peptide uperin-3.1 was equally effective as the others at inducing susceptibility to neutralizing antibody. This suggests that in addition to direct killing by a carpet-based mechanism, the peptides may simultaneously operate a different mechanism that exposes sequestered antigen without membrane removal.

Novel peptide therapeutics for treatment of infections.

As antibiotic resistance increases worldwide, there is an increasing pressure to develop novel classes of antimicrobial compounds to fight infectious disease. Peptide therapeutics represent a novel class of therapeutic agents. Some, such as cationic antimicrobial peptides and peptidoglycan recognition proteins, have been identified from studies of innate immune effector mechanisms, while others are completely novel compounds generated in biological systems. Currently, only selected cationic antimicrobial peptides have been licensed, and only for topical applications. However, research using new approaches to identify novel antimicrobial peptide therapeutics, and new approaches to delivery and improving stability, will result in an increased range of peptide therapeutics available in the clinic for broader applications.

Adult CST-null mice maintain an increased number of oligodendrocytes.

The galactolipids galactocerebroside and sulfatide have been implicated in oligodendrocyte (OL) development and myelin formation. Much of the early evidence for myelin galactolipid function has been derived from antibody and chemical perturbation of OLs in vitro. To determine the role of these lipids in vivo, we previously characterized mice lacking galactocerebroside and sulfatide and observed abundant, unstable myelin and an increased number of OLs. We have also reported that mice incapable of synthesizing sulfatide (CST-null) while maintaining normal levels of galactocerebroside generate relatively stable myelin with unstable paranodes. Additionally, Hirahara et al. (2004; Glia 45:269-277) reported that these CST-null mice also contain an increased number of OLs in the forebrain, medulla, and cerebellum at 7 days of age. Here, we further the findings of Hirahara et al. by demonstrating that the number of OLs in the CST-null mice is also increased in the spinal cord and that this elevated OL population is maintained through, at least, 7 months of age. Moreover, we show that the enhanced OL population is accompanied by increased proliferation and decreased apoptosis of oligodendrocytic-lineage cells. Finally, through ultrastructural analysis, we show that the CST-null OLs exhibit decreased morphological complexity, a feature that may result in decreased OL competition and increased OL survival.

Acute Intermittent Porphyria: Some Diagnoses are Only Made If Thought of.

A 20-year-old Asian, female, student nurse of thin body habitus (Body Mass Index 16.5) but otherwise previously well had numerous admissions to our centre under a variety of surgical sub-specialities over a 5-month period. Each month, coinciding with menses, she complained of non-specific abdominal discomfort in the absence of any other symptoms. With the exception of the presence of a sinus tachycardia coupled with incidental hyponatraemia full physical examinations and routine baseline investigations were unremarkable.

Hypolocomotion, anxiety and serotonin syndrome-like behavior contribute to the complex phenotype of serotonin transporter knockout mice.

Although mice with a targeted disruption of the serotonin transporter (SERT) have been studied extensively using various tests, their complex behavioral phenotype is not yet fully understood. Here we assess in detail the behavior of adult female SERT wild type (+/+), heterozygous (+/-) and knockout (-/-) mice on an isogenic C57BL/6J background subjected to a battery of behavioral paradigms. Overall, there were no differences in the ability to find food or a novel object, nest-building, self-grooming and its sequencing, and horizontal rod balancing, indicating unimpaired sensory functions, motor co-ordination and behavioral sequencing. In contrast, there were striking reductions in exploration and activity in novelty-based tests (novel object, sticky label and open field tests), accompanied by pronounced thigmotaxis, suggesting that combined hypolocomotion and anxiety (rather than purely anxiety) influence the SERT -/- behavioral phenotype. Social interaction behaviors were also markedly reduced. In addition, SERT -/- mice tended to move close to the ground, frequently displayed spontaneous Straub tail, tics, tremor and backward gait - a phenotype generally consistent with 'serotonin syndrome'-like behavior. In line with replicated evidence of much enhanced serotonin availability in SERT -/- mice, this serotonin syndrome-like state may represent a third factor contributing to their behavioral profile. An understanding of the emerging complexity of SERT -/- mouse behavior is crucial for a detailed dissection of their phenotype and for developing further neurobehavioral models using these mice.

Osmotic upshift transiently inhibits uptake via ABC transporters in gram-negative bacteria.

ATP-binding cassette transporters from several rhizobia and Salmonella enterica serovar Typhimurium, but not secondarily coupled systems, were inhibited by high concentrations (100 to 500 mM) of various osmolytes, an effect reversed by the removal of the osmolyte. ABC systems were also inactivated in isolated pea bacteroids, probably due to the obligatory use of high-osmolarity isolation media. Measurement of nutrient cycling in isolated pea bacteroids is impeded by this effect.

Crisis management during regional anaesthesia.

BACKGROUND: Regional anaesthesia is widely used and has been considered to pose few risks once the block is established. However, life threatening problems can occur both during the establishment and maintenance phases of a regional block which require prompt recognition and management. OBJECTIVES: To examine the role of a previously described core algorithm "COVER ABCD-A SWIFT CHECK", supplemented by a specific sub-algorithm for regional anaesthesia, in the management of problems arising in association with regional anaesthesia. METHODS: The potential performance of this structured approach was assessed for each of the relevant incidents among the first 4000 reported to the Australian Incident Monitoring Study (AIMS). RESULTS: There were 252 incidents involving regional anaesthesia, 6.3% of the first 4000 reports to AIMS. Of these, the majority (78%) involved the use of epidural or spinal anaesthesia. The core algorithm AB COVER CD properly applied, would have accounted for 45% of all problems, and is worth applying to eliminate unexpected problems unrelated to the regional anaesthesia technique itself. Hypotension and dysrhythmias made up over 30% of all incidents and accounted for all six deaths in the 252 incidents. The specific sub-algorithm for regional anaesthetic techniques accounted for 55% of all incidents: problems with delivery to the site of action, 49 cases (19%); problems with the block, 30 cases (12%); local anaesthetic toxicity, 30 cases (12%); trauma, infection, or pain, 14 cases (6%), wrong side or wrong patient, five cases (2%). CONCLUSION: Based on an analysis of 252 incidents, the core algorithm and the regional anaesthesia sub-algorithm, properly applied, would lead to swift recognition and appropriate management of problems arising in association with regional anaesthesia.

A prospective, randomised, single-blind pilot study to determine the effect of anaesthetic technique on troponin T release after off-pump coronary artery surgery.

Ischaemic damage to the myocardium inevitably occurs during coronary artery surgery. However, the extent of the damage may be influenced by the anaesthetic technique used. The most sensitive and reliable marker of myocardial damage is currently thought to be troponin T. We conducted a prospective, randomised, single-blind pilot study to determine the baseline values of troponin T release after off-pump coronary artery bypass surgery in 30 patients randomly allocated to receive either propofol, isoflurane or isoflurane and high thoracic epidural analgesia. All other treatment was standardised. Patients undergoing emergency surgery and those with unstable angina were excluded. Blood samples were taken at 0, 3, 6, 12, 24 and 48 h after surgery for troponin T analysis. Mean troponin T levels at 24 h were not significantly different between the groups (p = 0.41). These data allows appropriate power calculations for further, large-scale studies to determine the anaesthetic technique that provides optimal myocardial protection.

Predicting blood pressure reactivity and heart rate variability from mood state following coronary artery bypass surgery.

STUDY OBJECTIVES: Coronary Artery Bypass Graft (CABG) surgery is a common and successful procedure for revascularisation. However, the experience can induce emotional reactions prior to and following surgery. This study aimed to document changes in blood pressure (BP) reactivity and heart rate variability (HRV) following CABG surgery, and to determine the impact of mood state, particularly anxiety and depression upon cardiovascular functioning. METHOD: Twenty-two patients preparing to receive elective, first time CABG surgery were recruited from The Cardiothoracic Centre, Liverpool, UK and psychologically assessed using the Hospital Anxiety and Depression Scale (HAD), Global Mood Scale (GMS) and the Dispositional Resilience Scale (DRI). BP and heart rate responses were also measured during four conditions: baseline response; laboratory session; ambulatory monitoring; and self-initialised recordings during the ambulatory period. In addition, HRV was measured for 12 h in conjunction with the ambulatory monitoring period. All measures were assessed 1 week prior to surgery and 2 months following surgery. RESULTS: A significant decrease in negative mood and an increase in positive mood were reported following surgery. Forty percent of patients were clinically anxious and depressed prior to surgery although this was reduced to 27% after surgery. Depression was the strongest independent predictor of pre-operative BP and HRV whilst anxiety was most significantly related to follow-up BP reactivity. DBP was most strongly predicted by mood state. CONCLUSIONS: These results suggest that patients with higher levels of anxiety and depression are at risk of reduced HRV and increased BP reactivity in response to mental stressors. The study also strongly suggests that current patient services should be expanded to acknowledge the role of psychological factors within clinical prognosis after CABG surgery.

The experience of the intensive care unit in a British Army field hospital during the 2003 Gulf conflict.

Over the last few years the Surgeon General's Department has overseen a major update in equipment scales for medical units in the field; anaesthesia and intensive care. This is to meet the aspiration of the Defence Chiefs, that injured servicemen on active service should receive the same standard of care as available in the United Kingdom. This paper discusses the experiences of the Intensive Care Unit operating within a Field Hospital both during the initial war fighting phase and subsequent peace keeping phase of the 2003 Gulf conflict (OP TELIC). Observations are made on patient activity, treatment strategy, and equipment adequacy.