The objective of this study was to test a novel model of inducing AAA in different mouse strains and genders.
Materials and Methods
Male and female C57BL/6 and B6129 mice (N=5 per group) underwent peri-aortic dissection and porcine pancreatic elastase (30μl) or inactivated elastase application (5 min) to aorta. Aortic measurements were taken on day 0 and 14. Aortic samples were analyzed for histology, and zymography for MMP activity. Comparison statistics performed using unpaired t-test.
AAA phenotype (50% aortic increase), occurred in external elastase treated males (100%) and females (90%). No control animals developed AAAs. The aortic diameter was larger in C57BL/6 and B6129 elastase treated versus control males (p=0.0028 and p=<0.0001, respectively) and females (p<0.0001 and p=0.0458, respectively). Histology verified phenotype via disrupted internal elastic laminae. Macrophage counts in elastase treated animals were >6 fold higher than in controls (all groups significant). MMP9 activity was greater in elastase treated males and females in C57BL/6 (p=0.0031, p=0.0004) and B6129 (p=0.025, p=0.2) mice; MMP2 activity was greater in C57BL/6 vs. B6129 ME.
This rodent model produced AAAs in both genders and strains of mice. This model is simple, has little variability, and occurs in the infrarenal aorta, substantiating the external elastase model for future studies.
Alterations in network activity trigger compensatory changes in excitation and inhibition that restore neuronal firing rate to an optimal range. One example of such synaptic homeostasis is the downregulation of inhibitory transmission by chronic inactivity, in part, through the reduction of vesicular transmitter content. The enzyme glutamic acid decarboxylase 67 (GAD67) is critical for GABA synthesis, but its involvement in homeostatic plasticity is unclear. We explored the role of GAD67 in activity-dependent synaptic plasticity using a mouse line (Gad1−/−) in which GAD67 expression is disrupted by genomic insertion of the green fluorescent protein (GFP). Homozygous deletion of Gad1 significantly reduced miniature inhibitory postsynaptic current (mIPSC) amplitudes and GABA levels in cultured hippocampal neurons. The fractional block of mIPSC amplitude by a low affinity, competitive GABAA receptor antagonist was higher in GAD67-lacking neurons, suggesting that GABA concentration in the synaptic cleft is lower in knockout animals. Chronic suppression of activity by the application of tetrodotoxin (TTX) reduced mIPSC amplitudes and the levels of GAD67 and GABA. Moreover, TTX reduced GFP levels in interneurons, suggesting that GAD67 gene expression is a key regulatory target of activity. These in vitro experiments were corroborated by in vivo studies in which olfactory deprivation reduced mIPSC amplitudes and GFP levels in glomerular neurons in the olfactory bulb. Importantly, TTX-induced downregulation of mIPSC was attenuated in Gad1−/− neurons. Altogether, these findings indicate that activity-driven expression of GAD67 critically controls GABA synthesis and, thus, vesicular filling of the transmitter.
NMDARs (N-methyl-d-aspartate receptors) are critical for synaptic function throughout the CNS (central nervous system). NMDAR-mediated Ca2+ influx is implicated in neuronal differentiation, neuronal migration, synaptogenesis, structural remodelling, long-lasting forms of synaptic plasticity and higher cognitive functions. NMDAR-mediated Ca2+ signalling in dendritic spines is not static, but can be remodelled in a cell- and synapse-specific manner by NMDAR subunit composition, protein kinases and neuronal activity during development and in response to sensory experience. Recent evidence indicates that Ca2+ permeability of neuronal NMDARs, NMDAR-mediated Ca2+ signalling in spines and induction of NMDAR-dependent LTP (long-term potentiation) at hippocampal Schaffer collateral–CA1 synapses are under control of the cAMP/PKA (protein kinase A) signalling cascade. Thus, by enhancing Ca2+ influx through NMDARs in spines, PKA can regulate the induction of LTP. An emerging concept is that activity-dependent regulation of NMDAR-mediated Ca2+ signalling by PKA and by extracellular signals that modulate cAMP or protein phosphatases at synaptic sites provides a dynamic and potentially powerful mechanism for bi-directional regulation of synaptic efficacy and remodelling.
calcium; N-methyl-d-aspartate receptor (NMDAR); protein kinase; signalling; synaptic plasticity
Protein kinase C (PKC) enhances NMDA receptor (NMDAR) channel opening rate and promotes NMDAR delivery to the cell surface via SNARE-dependent exocytosis. Although the mechanisms of PKC potentiation are established, the molecular target of PKC is unclear. Here we show that synaptosomal-associated protein of 25 kDa (SNAP-25), a SNARE protein, is functionally relevant to PKC-dependent NMDAR insertion and identify serine residue-187 as the molecular target of PKC phosphorylation. Constitutively active PKC delivered via the patch pipette potentiated NMDA (but not AMPA) whole-cell currents in hippocampal neurons. Expression of RNAi targeting SNAP-25 or mutant SNAP-25(S187A) and/or acute disruption of the SNARE complex by treatment with BoNT A, BoNT B or SNAP-25 C-terminal blocking peptide abolished NMDAR potentiation. A SNAP-25 peptide and function-blocking antibody suppressed PKC potentiation of NMDA EPSCs at mossy fiber-CA3 synapses. These findings identify SNAP-25 as the target of PKC phosphorylation critical to PKC-dependent incorporation of synaptic NMDARs and document a postsynaptic action of this major SNARE protein relevant to synaptic plasticity.
Synaptic plasticity; ion channels; synaptic transmission; exocytosis; phosphorylation; trafficking
There is no well-defined means to identify the level of oral feeding skills (OFS) in preterm infants.
To determine whether OFS as reflected by the combination of proficiency (PRO, %ml taken during the first 5 min/ml prescribed) and rate of milk transfer (RT, ml/min) correlates with gestational age (GA), oral feeding performance (OT, %ml taken during a feeding/ml prescribed) and days from start to independent oral feeding (SOF-IOF). Our working premises are that PRO is reflective of infants’ actual feeding skills when fatigue is minimal and RT, monitored over an entire feeding session, reflects their overall skills when fatigue comes into play.
Infants (26–36 weeks GA) with prematurity as their principal diagnosis were recruited and monitored at their first oral feeding. GA was divided into 3 strata, 26–29, 30–33, and 34–36 weeks GA. OFS was divided into 4 levels delineated by PRO (≥ or <30%) and RT (≥ or <1.5 ml/min). ANOVA with post-hoc Bonferroni and multiple regression analyses were used.
OFS levels were correlated with GA. OT, PRO, and days from SOF-IOF were associated with OFS and GA, whereas RT was only correlated with OFS levels.
OFS is a novel objective indicator of infants’ feeding ability that takes into account infants’ skills and endurance. As a clinical tool, it can help caretakers monitor infants’ skills as they transition to oral feeding and identify oral feeding issues arising from immature skills and/or poor endurance.
Very low birth weight; Bottle feeding; Prematurity; Oral feeding evaluation
The healthy worker effect (HWE) is a well-known phenomenon. In this study we used the extensive registration of all Danish citizens to describe the magnitude of HWE among all Danish electricians and evaluated strategies for minimizing HWE bias of the association between occupation and mortality.
All Danish male citizens aged 26-56 years in the period 1984-1992 were followed for three years in several registers. We evaluated HWE bias among electricians because they were unexposed to detrimental occupational exposures. We compared electricians to three reference groups (general population, construction industry and carpenters/brick layers) and utilized analytical methods for minimizing HWE bias (lag time analyses, age-stratified analyses, marginal structural model and restriction to employed, newly employed or long-term workers).
The mortality rate was higher among electricians, who the year following active employment received incapacity benefits or were on long-term sick leave. Electricians receiving incapacity benefits, on long-term sick leave, unemployed, or with increased comorbidity index had lower odds of re-employment. Electricians had lower mortality rate (rate ratio,0.60;95%CI,0.52-0.69) compared to the general population, while electricians leaving employment had increased mortality (1.90;1.50-2.40). Adjusting for several social events slightly attenuated the estimates, while the marginal structural model did not minimize bias. Electricians had the same mortality as the construction industry and carpenters/brick layers. Mortality was comparable to the general population after three or more years of lag time.
In this nationwide study, employment as electricians had marked effect on mortality. Appropriate reference selection and lag time analyses minimized the HWE bias.
intravascular ultrasonography; virtual histology; vulnerable plaque
Rasch S, Sangild PT, Gregersen H., Schmidt M., Omari T, Lau C. The Preterm Piglet – an Animal Model for the Oesophageal Maturation in Preterm Neonates. Acta Paediatr ...... Stockholm. ISSN ......
Preterm infants have difficulty attaining independent oral feeding. This can ensue from inadequate sucking, swallowing, and/or respiration. In impeding bolus transport, immature oesophageal motility may also be a cause. As studies on the development of oesophageal motility are invasive in preterm infants, the preterm piglet was investigated as a potential research model.
Oesophageal motility (EM) of term (n=6) and preterm (n=15) piglets were monitored by manometry for 10 min immediately following bottle feeding on days 1-2 and 3-4 of life.
Piglets’ oral feeding performance and EM were similar to those of their human counterparts. Term piglets readily completed their feeding whereas their preterm counterparts did not. They also presented with greater peristaltic activity and propagating velocity. Peristaltic activity remained unchanged over time in preterm piglets, but an increase in synchronous and decrease in incomplete motor activity were noted. Preterm piglets that developed symptoms analogous to necrotizing enterocolitis (NEC) demonstrated uncharacteristic oesophageal activity.
Immature EM may cause oral feeding difficulties. NEC-like symptoms may adversely affect EM. The piglet is a valid research model for studying human infant oral feeding and oesophageal development.
oral feeding; prematurity; oesophageal motility
intravascular ultrasonography; virtual histology; vulnerable plaque
Protein kinase C (PKC) enhances NMDA receptor (NMDAR)-mediated currents and promotes NMDAR delivery to the cell surface via SNARE-dependent exocytosis. Although the mechanisms of PKC potentiation are established, the molecular target of PKC is unclear. Here we show that synaptosomal-associated protein of 25 kDa (SNAP-25), a SNARE protein, is functionally relevant to PKC-dependent NMDAR insertion, and identify serine residue-187 as the molecular target of PKC phosphorylation. Constitutively active PKC delivered via the patch pipette potentiated NMDA (but not AMPA) whole-cell currents in hippocampal neurons. Expression of RNAi targeting SNAP-25 or mutant SNAP-25(S187A) and/or acute disruption of the SNARE complex by treatment with BoNT A, BoNT B or SNAP-25 C-terminal blocking peptide abolished NMDAR potentiation. A SNAP-25 peptide and function-blocking antibody suppressed PKC potentiation of NMDA EPSCs at mossy fiber-CA3 synapses. These findings identify SNAP-25 as the target of PKC phosphorylation critical to PKC-dependent incorporation of synaptic NMDARs and document a postsynaptic action of this major SNARE protein relevant to synaptic plasticity.
Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease with complex genetic inheritance. Recently, single nucleotide polymorphisms (SNPs) in BANK1 and TNFSF4 have been shown to be associated with SLE in Caucasian populations, but it is not known whether they are also involved in the disease in other ethnic groups. Recent data from our genome-wide association study (GWAS) for 314 SLE cases and 920 controls collected in Hong Kong identified SNPs in and around BANK1 and TNFSF4 to be associated with SLE risk. On the basis of the results of the reported studies and our GWAS, SNPs were selected for further genotyping in 949 SLE patients (overlapping with the 314 cases in our GWAS) and non-overlapping 1042 healthy controls. We confirmed the associations of BANK1 and TNFSF4 with SLE in Chinese (BANK1, rs3733197, odds ratio (OR)=0.84, P=0.021; BANK1, rs17266594, OR=0.61, P=4.67 × 10−9; TNFSF4, rs844648, OR=1.22, P=2.47 × 10−3; TNFSF4, rs2205960, OR=1.30, P=2.41 × 10−4). Another SNP located in intron 1 of BANK1, rs4522865, was separately replicated by Sequenom in 360 cases and 360 controls and was also confirmed to be associated with SLE (OR=0.725, P=2.93 × 10−3). Logistic regression analysis showed that rs3733197 (A383T in ankyrin domain) and rs17266594 (a branch point-site SNP) from BANK1 had independent contributions towards the disease association (P=0.037 and 6.63 × 10−8, respectively). In TNFSF4, rs2205960 was associated with SLE independently from the effect of rs844648 (P=6.26 × 10−3), but not vice versa (P=0.55). These findings suggest that multiple independent genetic variants may be present within the gene locus, which exert their effects on SLE pathogenesis through different mechanisms.
SLE; BANK1; TNFSF4; Chinese; genetic association
To evaluate the effect of triage rapid initial assessment by doctor (TRIAD) on waiting time and processing time of an emergency department (ED) without extra staff.
A senior emergency doctor was put into triage instead of a consultation cubicle for seven shifts of 9 hours each. All the patients were assessed and necessary interventions started at the time of triage. Waiting time and processing time of various categories of patients were compared with a control group that was sampled during the week before the trial period.
In total, there were 1310 cases in the trial period and 1355 controls. Over a quarter (27%) of the patients received triage doctor interventions. The average waiting time was reduced by 38% and the average processing time by 23%. Patients without triage intervention also had a 24% shorter waiting time because of overall improvement in efficiency. Trauma patients and patients needing radiography particularly benefited from the new system. The waiting time and processing time of category 4 and 5 patients improved significantly as a result of more efficient processing of more urgent cases.
The waiting time and processing time of the ED were greatly reduced by TRIAD without extra manpower.
triage; waiting time; processing time
Several angiogenic growth factors including fibroblast growth factors 1 and 2 (FGF1 and FGF2) depend on heparan sulphate (HS) for biological activity. We previously showed that all cellular elements in ovarian tumour tissue synthesised HS but biologically active HS (i.e. HS capable of binding FGF2 and its receptor) was confined to ovarian tumour endothelium. In this study, we have sought to explain this observation. Heparan sulphate sulphotransferases 1 and 2 (HS6ST1 and HS6ST2) attach sulphate groups to C-6 of glucosamine residues in HS that are critical for FGF2 activation. These enzymes were strongly expressed by tumour cells, but only HS6ST1 was found in endothelial cells. Immunostaining with the 3G10 antibody of tissue sections pretreated with heparinases indicated that HS proteoglycans were produced by tumour and endothelial cells. These results indicated that, in contrast to the endothelium, HS produced by tumour cells may be modified by cell-surface heparanase (HPA1) or endosulphatase (SULF). Protein and RNA analysis revealed that HPA1 was strongly expressed by ovarian tumour cells in eight of ten specimens examined. HSULF-1, which removes specific 6-O-sulphate groups from HS, was abundant in tumour cells but weakly expressed in the endothelium. If this enzyme was responsible for the lack of biologically active HS on the tumour cell surface, we would expect exogenous FGF2 binding to be preserved; we showed previously that this was indeed the case although FGF2 binding was reduced compared to the endothelium and stroma. Thus, the combined effects of heparanase and HSULF could account for the lack of biologically active HS in tumour cells rather than deficiencies in the biosynthetic enzymes.
ovarian cancer; HS; FGF; heparanase; HSULF-1
Objectives: To assess the efficacy of the administration of magnesium as a method for the prevention of postoperative atrial fibrillation (AF) and to evaluate its influence on hospital length of stay (LOS) and mortality.
Methods: Literature search and meta-analysis of the randomised control studies published since 1966.
Results: 20 randomised trials were identified, enrolling a total of 2490 patients. Study sample size varied between 20 and 400 patients. Magnesium administration decreased the proportion of patients developing postoperative AF from 28% in the control group to 18% in the treatment group (odds ratio 0.54, 95% confidence interval (CI) 0.38 to 0.75). Data on LOS were available from seven trials (1227 patients). Magnesium did not significantly affect LOS (weighted mean difference −0.07 days of stay, 95% CI −0.66 to 0.53). The overall mortality was low (0.7%) and was not affected by magnesium administration (odds ratio 1.22, 95% CI 0.39 to 3.77).
Conclusion: Magnesium administration is an effective prophylactic measure for the prevention of postoperative AF. It does not significantly alter LOS or in-hospital mortality.
magnesium; atrial fibrillation; surgery
Safe and successful oral feeding requires proper maturation of sucking, swallowing and respiration. We hypothesized that oral feeding difficulties result from different temporal development of the musculatures implicated in these functions.
Sixteen medically stable preterm infants (26 to 29 weeks gestation, GA) were recruited. Specific feeding skills were monitored as indirect markers for the maturational process of oral feeding musculatures: rate of milk intake (mL/min); percent milk leakage (lip seal); sucking stage, rate (#/s) and suction/expression ratio; suction amplitude (mmHg), rate and slope (mmHg/s); sucking/swallowing ratio; percent occurrence of swallows at specific phases of respiration. Coefficients of variation (COV) were used as indices of functional stability. Infants, born at 26/27- and 28/29-week GA, were at similar postmenstrual ages (PMA) when taking 1–2 and 6–8 oral feedings per day.
Over time, feeding efficiency and several skills improved, some decreased and others remained unchanged. Differences in COVs between the two GA groups demonstrated that, despite similar oral feeding outcomes, maturation levels of certain skills differed.
Components of sucking, swallowing, respiration and their coordinated activity matured at different times and rates. Differences in functional stability of particular outcomes confirm that maturation levels depend on infants’ gestational rather than PMA.
Bottle feeding; Prematurity; Sucking skills; Suck-swallow-respiration; Swallowing skills; Very low birth weight
(1) To compare maternal characteristics and psychological stress profile among African-American, Caucasian and Hispanic mothers who delivered very low birthweight infants. (2) To investigate associations between psychosocial factors, frequency of milk expression, skin-to-skin holding (STS), and lactation performance, defined as maternal drive to express milk and milk volume.
Self-reported psychological questionnaires were given every 2 weeks after delivery over 10 weeks. Milk expression frequency, STS, and socioeconomic variables were collected.
Infant birthweight, education, and milk expression frequency differed between groups. Trait anxiety, depression and parental stress in a neonatal intensive care unit (PSS:NICU) were similar. African-American and Caucasian mothers reported the lowest scores in state anxiety and social desirability, respectively. Maternal drive to express milk, measured by maintenance of milk expression, correlated negatively with parental role alteration (subset of PSS:NICU) and positively with infant birthweight and STS. Milk volume correlated negatively with depression and positively with milk expression frequency and STS.
Differences between groups were observed for certain psychosocial factors. The response bias to self-reported questionnaires between groups may not provide an accurate profile of maternal psychosocial profile. With different factors correlating with maintenance of milk expression and milk volume, lactation performance can be best enhanced with a multi-faceted intervention program, incorporating parental involvement in infant care, close awareness and management of maternal mental health, and encouragement for frequent milk expression and STS.
prematurity; milk expression; milk production; maternal stress; depression; anxiety; social desirability
The case is reported of a 75 year old woman who presented with recurrent nocturnal episodes of acute pulmonary oedema. The cause was uncertain as she had normal cardiothoracic ratio on chest radiography and normal left ventricular systolic and diastolic function by transthoracic echocardiogram. Another transthoracic echocardiogram was repeated when she was recumbent for an hour and had a full stomach. It showed a striking finding of severe left atrial compression by an external structure. Computed tomography of the thorax showed an intrathoracic mass behind the left atrium causing external compression of the left atrium suggestive of a sliding hiatus hernia. Cardiac catheterisation confirmed the diagnosis by showing a pronounced rise of pulmonary capillary wedge pressure in the recumbent position compared with the sitting up position.
atrial fibrillation; pacemaker; sick sinus syndrome
Objective: To compare the haemodynamic effect of low dose midazolam and etomidate as induction agent in emergency department rapid sequence intubation.
Methods: A prospective observational study in two phases. In phase one, midazolam 2–4 mg was used as induction agent and in phase two, etomidate 0.2–0.3 mg/kg was used. The haemodynamic data were recorded before and after intubation for comparison. Changes in mean systolic blood pressure were analysed with SPSS software.
Results: A 10% decrease in mean systolic blood pressure was observed in the midazolam group (p = 0.001) while there was no significant change in the etomidate group. Some 19.5% of patients had hypotension after being given midazolam while only 3.6% with etomidate (p = 0.002). Patients older than 70 tended to have more hypotension episodes but the difference was not statistically significant.
Conclusions: Midazolam, even in low dose, was more likely than etomidate to cause significant hypotension when used as an induction agent for rapid sequence intubation. Etomidate is a better alternative.
Images in cardiology
The exact patho-aetiology of systemic lupus erythematosus (SLE) remains elusive. An extremely complicated and multifactorial interaction among various genetic and environmental factors is probably involved. Multiple genes contribute to disease susceptibility. The interaction of sex, hormonal milieu, and the hypothalamo–pituitary–adrenal axis modifies this susceptibility and the clinical expression of the disease. Defective immune regulatory mechanisms, such as the clearance of apoptotic cells and immune complexes, are important contributors to the development of SLE. The loss of immune tolerance, increased antigenic load, excess T cell help, defective B cell suppression, and the shifting of T helper 1 (Th1) to Th2 immune responses leads to B cell hyperactivity and the production of pathogenic autoantibodies. Finally, certain environmental factors are probably required to trigger the disease.
aetiology; pathogenesis; genetic; interaction; autoimmune; autoantibody
Background: Plasma exchange may be useful for treating patients with fulminant hepatic failure but during the procedure growth factors that are important for hepatic regeneration are discarded. Addition of a selective plasma filter to the plasmapheresis circuit could eliminate protein bound toxic substances and retain growth factors for hepatic regeneration. This process is called selective plasma filtration.
Aims: To determine if selective plasma filtration could be a useful treatment modality for fulminant hepatic failure.
Methods: The system was tested in five groups of pigs with fulminant hepatic failure induced by galactosamine: group I, diseased control group (n=5); group II, sham control, (n=6); group III, plasma exchange (n=6); group IV, treatment with AC-1770 selective plasma filter (n=7); and group V, treatment with AC-1730 selective plasma filter which had a smaller pore size than AC-1770 (n=7). Fresh pig plasma was given to replace filtered plasma in pigs of groups III, IV, and V. Treatment was initiated 48 hours after administration of 0.75 g/kg galactosamine. The efficacy of selective plasma filtration was assessed by survival rate and improvement in haematological, biochemical, and immunohistological parameters.
Results: Pigs treated with AC-1770 or AC-1730 selective plasma filters survived longer than the other groups (group I: 55 (10) hours; group II: 68 (7) hours; group III: 91 (10) hours; group IV: 269 (156) hours; group V: 950 (555) hours). One pig in group IV survived for 50 days; one pig in group V survived for 77 days and another pig in group V is still alive (>150 days). After treatment, plasma levels of aspartate aminotransferase, bilirubin, bile acid, ammonia, lactate dehydrogenase, and α-glutathione-S-transferase decreased. Substantial amounts of tumour necrosis factor α (TNF-α) and endotoxin were found in the filtrate. The selective plasma filtration groups retained significantly higher amounts of hepatocyte growth factor than plasma exchange alone. Similar TNF-α clearance was observed in the selective plasma filtration groups and the plasma exchange group. On day 4, significant improvement in liver function, as measured by the indocyanine green clearance test, was observed in groups IV and V but not in the other groups. A higher regeneration index of hepatocytes was also observed in the groups treated with AC-1770 and AC-1730 selective plasma filters.
Conclusion: Selective plasma filtration improved survival time and expedited liver regeneration in pigs with fulminant hepatic failure.
fulminant hepatic failure; AC-1770; AC-1730; selective plasma filtration; plasma exchange