Interleukin-1 beta (IL-1 beta) and tumour necrosis factor (TNF) inhibit long-term potentiation in the rat dentate gyrus in vitro

The effects of the cytokine, interleukin-1 beta (IL-1 beta), and its receptor antagonist IL-1ra, were studied on long-term potentiation in the dentate gyrus of rat hippocampal slices. Field excitatory postsynaptic potentials were recorded extracellularly in the molecular region of the dentate gyrus in response to stimulation of the medial perforant path. Low frequency synaptic transmission was unaffected by IL-1 beta (1 ng/ml), but pre-treatment with IL-1 beta completely blocked induction of long-term potentiation. Co-application of IL-1 beta and IL-1ra (100 ng/ml) attenuated the inhibitory effect of IL-1 beta. In parallel with these findings, we demonstrate that IL-1 beta also inhibited 45Ca influx into the slices. The inhibitory effect of IL-1 beta on induction was mimicked by tumour necrosis factor (TNF; 4.5 ng/ml) and lipopolysaccharide (LPS; 10 micrograms/ml). These results indicate a modulatory role for cytokines in hippocampus and suggest that the inhibitory effect of IL-1 beta on long-term potentiation may relate to its inhibitory effect on calcium channel activity.

A review of dental implants and infection

Dental implants have become increasingly common for the management of tooth loss. Despite their placement in a contaminated surgical field, success rates are relatively high. This article reviews dental implants and highlights factors leading to infection and potential implant failure. A literature search identified studies analysing the microbial composition of peri-implant infections. The microflora of dental peri-implantitis resembles that found in chronic periodontitis, featuring predominantly anaerobic Gram-negative bacilli, in particular Porphyromonas gingivalis and Prevotella intermedia, anaerobic Gram-negative cocci such as Veillonella spp. and spirochaetes including Treponema denticola. The role of Staphylococcus aureus and coagulase-negative staphylococci that are typically encountered in orthopaedic infections is debatable, although they undoubtedly play a role when isolated from clinically infected sites. Likewise, the aetiological involvement of coliforms and Candida spp. requires further longitudinal studies. Currently, there are neither standardised antibiotic prophylactic regimens for dental implant placement nor universally accepted treatment for peri-implantitis. The treatment of infected implants is difficult and usually requires removal. In the UK there is no systematic post-surgical implant surveillance programme. Therefore, the development of such a project would be advisable and provide valuable epidemiological data.

Magnetic Flux-Line Lattices and Vortices in the Copper Oxide Superconductors

A variety of recent experiments on both the static and the dynamic properties of vortices and flux-line lattices in the mixed state of the copper oxide superconductors are discussed. The experiments are of two basic types: (i) experiments that image the magnetic flux patterns either with magnetic decoration or neutrons and give information about static structures, and (ii) experiments that explore the dynamics of vortices either through the resistivity or other electrodynamic responses of the material. Results of these experiments argue in favor of the existence of a true phase transition in the high-field vortex state from a low-temperature superconducting vortex glass phase into a disordered high-temperature vortex fluid phase. The vortex glass phase transition model does a good job of explaining high-precision measurements of the dynamics at the transition. At low fields and temperatures, very long range hexatic order in the flux-line lattice is observed.

Dietary supplementation with vitamin E reverses the age-related deficit in long term potentiation in dentate gyrus

Long term potentiation (LTP) in dentate gyrus is impaired in aged rats, and this has been associated with an age-related decrease in membrane arachidonic acid concentration. In this study, we considered whether the trigger for this age-related decrease in arachidonic acid might be increased lipid peroxidation stimulated by the proinflammatory cytokine, interleukin-1beta. Groups of aged and young rats were fed on a control diet or a diet supplemented with alpha-tocopherol and assessed for their ability to sustain LTP. Aged rats fed on the control diet exhibited an impaired ability to sustain LTP and analysis of tissue prepared from these rats exhibited increased interleukin-1beta, increased lipid peroxidation, and decreased membrane arachidonic acid concentration compared with young rats fed on either diet. Aged rats fed on the supplemented diet sustained LTP in a manner indistinguishable from young rats, and the age-related increases in interleukin-1beta and lipid peroxidation and the decrease in membrane arachidonic acid concentration were all reversed. We propose that interleukin-1beta may be the trigger that induces these age-related changes and may therefore be responsible for the deficit in long term potentiation in aged rats. The observation that alpha-tocopherol reverses these changes is consistent with the hypothesis that some age-related changes in hippocampus might derive from oxidative stress.

Interleukin-1 beta inhibits glutamate release in hippocampus of young, but not aged, rats

The proinflammatory cytokine, interleukin-1, is synthesized in neuronal and glial cells and is released in response to stress/injury. IL-1 exerts profound effects on the central nervous system, which include an inhibitory effect on synaptic activity in hippocampus, a brain area expressing a high density of IL-1 receptors. We report that IL-1 beta has an inhibitory effect on KCl-stimulated release of glutamate and KC1-stimulated [45Ca] influx in synaptosomes prepared from hippocampus of 4-month-old rats. These effects were inhibited by the endogenous receptor antagonist, IL-1ra, and by the phospholipase A2 (PLA2) inhibitor, quinacrine, suggesting that IL-1 receptor activation is coupled to PLA2. An inhibitory effect of IL-1 beta on protein kinase C activity was also observed. KC1-induced calcium-dependent release and calcium influx, and protein kinase C activity were significantly decreased in hippocampal synaptosomes prepared from 22-month-old compared to 4-month-old animals. In contrast to the inhibitory effect of IL-1 beta in synaptosomes prepared from young adult animals, no effect was observed on release, calcium influx, or protein kinase C activity in synaptosomes prepared from aged animals. We report that there is an age-related increase in expression of IL-1 beta in hippocampus and propose that this change may underlie the attenuated responses to IL-1 beta in hippocampus of aged animals.

Spontaneous laceration of ascending aorta

Spontaneous laceration of the ascending aorta may result in (1) through-and-through laceration causing hemopericardium, (2) limited intramural dissection of blood (incomplete dissecting aneurysm), or (3) classical dissecting aneurysm. The latter is the most common manifestation. Background conditions include either extensive cystic medial necrosis (as may be seen in Marfan's syndrome) or hypertension. The latter condition is universally associated with cystic medial necrosis but classically the medial lesion is of minimal degree. Aortic stenosis may be an underlying cause of spontaneous laceration of the ascending aorta.

Bioavailability of n-3 polyunsaturated fatty acids (PUFA) in foods enriched with microencapsulated fish oil

OBJECTIVE

Incorporation of fish oil into food products provides a means of increasing n-3 fatty acid intake, particularly in populations where fish consumption remains low. The aim of the present study was to evaluate the bioavailability of n-3 PUFA in microencapsulated fish-oil-enriched foods compared with an equal amount of n-3 PUFAs contained in fish oil capsules.

METHODS

Twenty-five healthy female volunteers were randomly assigned to one of two groups for the 4-week intervention: one group received 0.9 g of n-3 PUFA/day as fish oil capsule (capsule group), while the second group (food group) received an equal amount of n-3 PUFA/day from enriched foods. Baseline and post-intervention samples were analysed for platelet fatty acid composition.

RESULTS

There was no significant difference in the change in platelet arachidonic acid (AA), eicosapentaenoic acid (EPA), or docosahexaenoic acid (DHA) between the two groups following the intervention.

CONCLUSIONS

The results indicate that n-3 PUFA from microencapsulated fish-oil-enriched foods are as bioavailable as n-3 PUFA in a capsule. Fortification of foods with microencapsulated fish oil, therefore, offers an effective way of increasing n-3 PUFA intakes and status in line with current dietary recommendations.

Molecular-weight dependence of the glass transition temperature of freely-standing poly(methyl methacrylate) films

We have used transmission ellipsometry to measure the glass transition temperature, T(g), of freely-standing films of atactic and syndiotactic poly(methyl methacrylate) (PMMA). We have prepared films with different molecular weights, MW, (159 x 10(3) < M (w) < 1.3 x 10(6)) and film thicknesses, h, ( 30 nm < h < 200 nm). For the high-MW ( M (w) > 509 x 10(3)) atactic PMMA films, we find that T(g) decreases linearly with decreasing h, which is qualitatively similar to previous results obtained for high-MW freely-standing polystyrene (PS) films. However, the overall magnitude of the T(g) reduction is much less (by roughly a factor of three) for the high-MW freely-standing PMMA films than for freely-standing PS films of comparable MW and h. The observed differences between the freely-standing PMMA and PS film data suggest that differences in chemical structure determine the magnitude of the T(g) reduction and we discuss the possible origins of these differences. Our analysis of the MW-dependence of the T(g) reductions suggests that the mechanism responsible for the MW-dependent T(g) reductions observed in the high-MW freely-standing films is different than that responsible for the MW-independent T(g) reductions observed in the low-MW freely-standing and supported films.

CT imaging of solid renal masses: pitfalls and solutions

Computed tomography (CT) remains the first-line imaging test for the characterisation of renal masses; however, CT has inherent limitations, which if unrecognised, may result in errors. The purpose of this manuscript is to present 10 pitfalls in the CT evaluation of solid renal masses. Thin section non-contrast enhanced CT (NECT) is required to confirm the presence of macroscopic fat and diagnosis of angiomyolipoma (AML). Renal cell carcinoma (RCC) can mimic renal cysts at NECT when measuring <20 HU, but are usually heterogeneous with irregular margins. Haemorrhagic cysts (HC) may simulate solid lesions at NECT; however, a homogeneous lesion measuring >70 HU is essentially diagnostic of HC. Homogeneous lesions measuring 20-70 HU at NECT or >20 HU at contrast-enhanced (CE) CT, are indeterminate, requiring further evaluation. Dual-energy CT (DECT) can accurately characterise these lesions at baseline through virtual NECT, iodine overlay images, or quantitative iodine concentration analysis without recalling the patient. A minority of hypo-enhancing renal masses (most commonly papillary RCC) show indeterminate or absent enhancement at multiphase CT. Follow-up, CE ultrasound or magnetic resonance imaging (MRI) is required to further characterise these lesions. Small (<3 cm) endophytic cysts commonly show pseudo-enhancement, which may simulate RCC; this can be overcome with DECT or MRI. In small (<4 cm) solid renal masses, 20% of lesions are benign, chiefly AML without visible fat or oncocytoma. Low-dose techniques may simulate lesion heterogeneity due to increased image noise, which can be ameliorated through the appropriate use of iterative reconstruction algorithms.

Age-related changes in oxidative mechanisms and LTP are reversed by dietary manipulation

Aged rats exhibit an impaired ability to sustain long-term potentiation in dentate gyrus which correlates with a decrease in arachidonic acid concentration. Here we confirm the previous finding that dietary supplementation with arachidonic acid and its precursor, gamma-linolenic acid, reversed the impairment in LTP in aged rats and report that there is a significant correlation between membrane arachidonic acid concentration and response to tetanic stimulation. We observed that age was associated with decreases in the concentration of vitamins C and E and increased activity of superoxide dismutase, indicative of a compromise in antioxidative defenses; these changes were paralleled by increases in interleukin-1beta (IL-1beta) concentration and lipid peroxidation. Dietary manipulation restored polyunsaturated fatty acid concentrations to values observed in tissue prepared from young rats and reversed the age-related changes in vitamins E and C, IL-1beta concentration and superoxide dismutase activity. We propose that these changes reverse the increase in lipid peroxidation and thereby the age-related change in polyunsaturated fatty acids.

Shoulder hemiarthroplasty for proximal humeral fractures

Shoulder hemiarthroplasty is a well-accepted surgical procedure for the treatment of specific subtypes of proximal humeral fractures, including four-part fractures, three-part fractures associated with severe osteopenia, head-splitting and severe articular impression fractures. Careful patient assessment and meticulous surgical technique are essential to prevent complications. The results are satisfactory in approximately 80% of cases. The results are better in younger patients and in acute versus chronic fractures. There are a significant number of complications that are related to technical details of the procedure. Careful placement of the prosthesis and secure reattachment of the tuberosities to the shaft reduce the chance of complication following surgery. Good to excellent results in terms of range of motion and pain relief can be expected in most patients.

Root canal treatment and general health: a review of the literature

REVIEW

The focal infection theory was prominent in the medical literature during the early 1900s and curtailed the progress of endodontics. This theory proposed that microorganisms, or their toxins, arising from a focus of circumscribed infection within a tissue could disseminate systemically, resulting in the initiation or exacerbation of systemic illness or the damage of a distant tissue site. For example, during the focal infection era rheumatoid arthritis (RA) was identified as having a close relationship with dental health. The theory was eventually discredited because there was only anecdotal evidence to support its claims and few scientifically controlled studies. There has been a renewed interest in the influence that foci of infection within the oral tissues may have on general health. Some current research suggests a possible relationship between dental health and cardiovascular disease and published case reports have cited dental sources as causes for several systemic illnesses. Improved laboratory procedures employing sophisticated molecular biological techniques and enhanced culturing techniques have allowed researchers to confirm that bacteria recovered from the peripheral blood during root canal treatment originated in the root canal. It has been suggested that the bacteraemia, or the associated bacterial endotoxins, subsequent to root canal treatment, may cause potential systemic complications. Further research is required, however, using current sampling and laboratory methods from scientifically controlled population groups to determine if a significant relationship between general health and periradicular infection exists.

Negative thermal expansion in hybrid improper ferroelectric Ruddlesden-Popper perovskites by symmetry trapping

We present new results on the microscopic nature of the ferroelectricity mechanisms in Ca3 Mn2O7 and Ca3Ti2O7. To the first approximation, we confirm the hybrid improper ferroelectric mechanism recently proposed by Benedek and Fennie for these Ruddlesden-Popper compounds. However, in Ca3Mn2O7 we find that there is a complex competition between lattice modes of different symmetry which leads to a phase coexistence over a large temperature range and the "symmetry trapping" of a soft mode. This trapping of the soft mode leads to a large uniaxial negative thermal expansion (NTE) reaching a maximum between 250 and 350 K (3.6×10^(-6)  K^{-1}) representing the only sizable NTE reported for these and related perovskite materials to date. Our results suggest a systematic strategy for designing and searching for ceramics with large NTE coefficients.

Care home staff knowledge of oral care compared to best practice: a West of Scotland pilot study

AIM

To evaluate care home (N) staff knowledge of oral care provision for dependent older people in comparison to guidelines from NHS Quality Improvement Scotland (NHSQIS). This pilot study also aimed to identify barriers to delivering oral care and determine if oral health educator (OHE) training had an effect upon staff knowledge of oral care delivery.

SETTING

This cross-sectional analytic investigation was undertaken within the Greater Glasgow & Clyde area between 2005 and 2007.

METHODS

From 33 care homes (N), 28 participated in data gathering through an interview schedule involving 109 staff. A 'knowledge check-list' founded upon daily oral care guidelines from the NHSQIS best practice statement (BPS) served as a template for knowledge assessment. An OHE undertook small group discussions related to the BPS in a sub-group of original participants and a second round of data was collected.

RESULTS

The majority of surveyed staff (n = 86, 79%) agreed that residents required assistance with oral care and placed oral care (n = 85, 78%) in a moderate to high priority. However, only 57% of managers and 49% of nurses had received training in oral care provision. Most staff (79% of managers, 85% of nurses) were unaware of the NHSQIS BPS. Deficiencies in knowledge were identified in several areas of the BPS. In particular, knowledge in the care of the natural dentition was inadequate. Between pre- and post-OHE training, the research suggests the following areas are liable to change: prioritisation given to oral care (p = 0.01), perceived competence (p <0.0001) and confidence in providing oral care advice (p <0.0001). Following OHE intervention, staff knowledge in oral care procedures compliant with best practice guidelines increased by 45%.

CONCLUSIONS

Knowledge of oral health provision by those responsible for the care of home residents was deficient. An OHE training programme structured around the NHSQIS BPS demonstrated a measurable increase in levels of staff knowledge of oral care procedures.

Inhibitory effect of human hydrosalpingeal fluid on mouse preimplantation embryonic development is significantly reduced by the addition of lactate

Implantation and pregnancy rates following in-vitro fertilization-embryo transfer are reduced in the presence of hydrosalpinges, but the basis of the inhibition is unknown. We examined the effect of hydrosalpingeal fluid on preimplantation development of mouse embryos. Embryos cultured in 100% hydrosalpingeal fluid were significantly inhibited developmentally as compared to embryos cultured in 100% defined medium, which served as controls. In contrast, embryos cultured in 50% hydrosalpingeal fluid/50% defined medium reached the blastocyst stage at the same frequency as the controls. When lactate (final concentration 10 mM) was added to 100% hydrosalpingeal fluid, the percentage of cultured embryos that reached the blastocyst stage was significantly increased as compared to 100% hydrosalpingeal fluid, although the percentage was slightly lower than that observed for embryos cultured in the 100% defined medium. A similar but less pronounced effect occurred when pyruvate was added to hydrosalpingeal fluid. These results do not support the concept that a potent embryotoxic agent is commonly present in hydrosalpingeal fluid. Rather, they are consistent with the notion that the inhibitory effect of hydrosalpingeal fluid on embryonic development is due to the absence of essential factors, and that this deficiency can be largely corrected by the addition of energy sources.