Psychological wellbeing in parents of children with Down syndrome: A systematic review and meta-analysis

We report a review examining the psychological wellbeing of parents of children with Down syndrome (DS) relative to that of parents of typically developing (TD) children. A systematic search identified 57 relevant studies, which were synthesised meta-analytically. Relative to their counterparts with TD children, mothers and fathers of children with DS reported higher levels of parenting stress (mothers: g = 0.57, 95% CI [0.33, 0.81]; fathers: g = 0.40, [0.24, 0.56]), depressive symptoms (mothers: g = 0.42, [0.23, 0.61]; fathers: g = 0.25, [0.02, 0.48]) and psychological distress (mothers: g = 0.45, [0.30, 0.60]; fathers: g = 0.63, [0.26, 0.99]). Small effects were found for anxiety for mothers (g = 0.16, [0.03, 0.29]), with no differences for fathers (g = 0.03, [-0.25, 0.32]). No group differences were found for positive impact of parenting (mothers: g = -0.09, [-0.25, 0.07]; fathers: g = -0.04, [-0.30, 0.22]), while evidence concerning other positive wellbeing outcomes was limited. No significant moderating effects of child age range, country income level, or group differences in parental education level were identified, but limited subgroup analyses were possible. Raising a child with DS may be associated with elevated stress, depressive symptoms, and psychological distress for mothers and fathers. However, levels of parenting reward appear equivalent to those experienced by parents raising TD children.

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.

Synthesis and structure of Zr(iv)- and Ce(iv)-based CAU-24 with 1,2,4,5-tetrakis(4-carboxyphenyl)benzene

Eight-fold connection of hexanuclear clusters containing Zr(iv) or Ce(iv) through rigid, rectangular tetracarboxylate ions yields new MOFs with scu topology.

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.

Availability of manufacturers' information on efficacy and compatibility of detergents used for cleaning dental instruments

AIM

To review physico-chemical data supplied for commercially available detergents marketed for manual and/or ultrasonic cleansing of reusable dental instruments.

METHOD

Manufacturers/suppliers of commercially available detergents for manual or ultrasonic cleaning of dental instruments within primary dental care were invited to supply product information. A structured questionnaire requested details on a range of physical and chemical properties for each detergent.

RESULTS

Seventeen detergent manufacturers/suppliers, encompassing 31 commercially available detergents were identified. Ten of the 17 manufacturers provided information on 23 (74%) of the detergent formulations. Nine detergents were of neutral pH, ten mild alkalis (pH 7.5-10.5) and four strong alkalis (pH >10.5). Sixteen detergents were recommended for ultrasonic and manual cleaning, four stated ultrasonic use and three manual only. Ten detergents cited enzymatic activity as their main mode of action, but only six manufacturers provided detailed information. Four detergents recommended by manufacturers as suitable for manual washing had a strong alkaline pH (>10.5), presenting chemical hazards to users. Two strong alkaline detergents did not warn users of potential adverse effects of such alkaline solutions (corrosion) upon aluminium containing instruments. Only one detergent had investigated the potential toxicity of detergent residuals remaining on instruments after reprocessing.

CONCLUSION

It has proven challenging to collate physico-chemical data on detergents suitable for use in manual and/or ultrasonic cleaning of dental instruments in general dental practice. Standardisation of information on the nature and efficacy of dental detergents in a readily accessible form would be beneficial to dental practice.

Joint tenderness and swelling in biologic-treated inflammatory arthritis patients - a tricky trade off?

OBJECTIVE

To compare the pattern of joint responses in patients with rheumatoid arthritis and psoriatic arthritis treated with TNF inhibitor (TNFi) therapy.

METHODS

A total of 182 PsA/Rheumatoid arthritis (RA) patients attending the rheumatology unit of a tertiary referral centre in Ireland were recruited and prospectively followed up by the attendant rheumatologists. Clinical progress of the patients was noted at baseline and 6 months after starting TNFi therapy.

RESULTS

A total of 114 RA and 68 PsA patients were assessed; 20% of the patients had one of either tender joints or swollen joints after 6 months of therapy. Rheumatoid arthritis patients had a significantly higher proportion of non-tender swollen joints compared with PsA patients, whereas PsA patients had a higher proportion of tender non-swollen joints (p < 0.05).

CONCLUSION

Residual joint swelling was found more commonly in RA patients than in PsA patients following TNFi therapy, whereas residual tender joints occurred more frequently in PsA; this may reflect enthesiopathy or periostitis.

Raman Spectroscopy of Size Selected, Matrix Isolated Si Clusters

We report results of Raman spectroscopy of size selected, matrix isolated Si clusters. Cluster ions produced by laser vaporization are size selected by a quadruple mass spectrometer and co-deposited with cryogenic matrices onto a substrate at ∼15K. A surface-plasmon-polariton-enhanced Raman geometry is used to gain adequate signal.

The observed vibrational frequencies from Si4, Si6 and Si7 are compared with theoretically calculated Raman active modes based on the structures of planar rhombus, distorted octahedron and pentagonal bipyramid, respectively. The agreement is excellent. Cluster agglomeration is observed when cluster concentrations exceed ∼0.3% by volume in the matrix and/or with annealing at ∼28K, below the temperature of matrix evaporation.

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.

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.

Under-reporting of notifiable infectious disease hospitalizations in a health board region in Ireland: room for improvement?

Rapid notification of infectious diseases is essential for prompt public health action and for monitoring of these diseases in the Irish population at both a local and national level. Anecdotal evidence suggests, however, that the occurrence of notifiable infectious diseases is seriously underestimated. This study aims to assess the level of hospitalization for notifiable infectious diseases for a 6-year period in one health board region in Ireland and to assess whether or not there was any under-reporting during this period. All hospital in-patient admissions from 1997 to 2002 inclusive with a principal diagnosis relating to 'infectious and parasitic diseases' (ICD codes 001-139) of residents from a health board region in Ireland were extracted from the Hospital In-Patient Enquiry System (HIPE). All notifiable infectious diseases were identified based on the 1981 Irish Infectious Disease Regulations and the data were analysed in the statistical package, JMP. These data were compared with the corresponding notification data. Analysis of the hospital in-patient admission data revealed a substantial burden associated with notifiable infectious diseases in this health board region: there were 2758 hospitalizations by 2454 residents, 17,034 bed days and 33 deaths. The statutory notification data comprises both general practitioner and hospital clinician reports of infectious disease. Therefore, only in cases where there are more hospitalizations than notifications can under-reporting be demonstrated. This occurred in nine out of 22 notifiable diseases and amounted to an additional 18% of notifications (or 572 cases) which were 'missed' due to hospital clinician under-reporting. The majority of these under-reported cases were for viral meningitis (45%), infectious mononucleosis (27%), viral hepatitis C unspecified (15%) and acute encephalitis (5.8%). This study has highlighted the extent of under-reporting of hospitalized notifiable infectious diseases, in a health board region in Ireland, which is a cause for concern from a surveillance point of view. If this under-reporting is similar in other health boards, then it would appear that the epidemiology of some notifiable diseases is incomplete both regionally and nationally. This under-reporting negatively impacts on the effectiveness of the notification process as a 'real-time' surveillance tool and an early warning system for outbreaks.

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.

Trends in viral meningitis hospitalisations and notifications in the North Eastern Health Board (1997 - 2001): a cause for concern?

This study aimed to compare trends in both hospital admissions and notifications of viral meningitis in the North Eastern Health Board (NEHB). Hospital admissions from 1997 to 2001, involving NEHB residents with an infectious disease diagnosis, were examined and viral meningitis cases were analyzed. During this period 265 NEHB residents were admitted to hospital with viral meningitis--an increase of 429% between 1997 and 2001 with the bulk of this increase during 2000 and 2001. A total of 1,234 bed days were taken up by this cohort and the mean length of stay was 4.5 days (95% CI 4.2 - 4.9). The number of viral meningitis notifications in the NEHB was 38 (ranging from 4 in 1997 to 11 in 2001). This number is much lower than expected given the corresponding number of hospital admissions for the same period. Thus, most cases were not notified which means that current surveillance systems under-estimate the disease burden of viral meningitis. Such under-reporting has implications for infectious disease policy in Ireland.

An evaluation of the use of tooth temperature to assess human pulp vitality

AIM

To evaluate change in tooth surface temperature following a thermal stimulus as a simple and reliable method to assess the presence and the extent of blood flow through teeth.

METHODOLOGY

Miniature thermometers were used to measure the relationship between surface temperature of teeth and internal flow of 37 degrees C water (in vitro) or blood (in vivo). In addition, thermal stimuli were applied to the external surface of the teeth, and the rate of temperature recovery was related to internal flow.

RESULTS

Under in vitro conditions, the surface temperature of teeth and rate of temperature recovery were related to the rate of internal water flow. However, in vivo neither standing surface temperature (P = 0.47) nor rate of temperature recovery (P = 0.19) were significantly related to evidential pulp vitality.

CONCLUSION

Change in the surface temperature of teeth is not suitable as a simple clinical means to assess pulp vitality.

Comparison of AOPs for the removal of natural organic matter: performance and economic assessment

Control of disinfection by-products during water treatment is primarily achieved by reducing the levels of organic precursor species prior to chlorination. Many waters contain natural organic matter at levels up to 15 mg L(-1); therefore it is necessary to have a range of control methods to support conventional coagulation. Advanced oxidation processes are such processes and in this paper the Fenton and photo-Fenton processes along with photocatalysis are assessed for their NOM removal potential. The performance of each process is shown to be dependent on pH and chemical dose as well as the initial NOM concentration. Under optimum conditions the processes achieved greater than 90% removal of DOC and UV254 absorbance. This removal led to the THMFP of the source water being reduced from 140 to below 10 microg L(-1), well below UK and US standards. An economic assessment of the processes revealed that currently such processes are not economic. With advances in technology and tightening of water quality standards these processes should become economically feasible options.

Histopathological patterns of melanoma metastases in sentinel lymph nodes

AIMS

Sentinel lymph node biopsy (SLNB) is an important component in the staging and treatment of cutaneous melanoma (CM). The medical literature provides only limited information regarding melanoma sentinel lymph node (SLN) histology. This report details the specific histological patterns of melanoma metastases in sentinel lymph nodes (SLNs) and highlights some key factors in evaluating SLNs for melanoma.

METHODS

From 281 SLNB cases between June 1998 and May 2002, 79 consecutive cases of SLN biopsies positive for metastases from CM were retrospectively reviewed. The important characteristics of the SLNs and the metastatic foci are described.

RESULTS

The median size of positive SLNs was 17 mm (range, 5-38). SLNs had a median of two metastatic foci (range, 1-11), with the largest foci being a median of 1.1 mm in size (range, 0.05-24). S-100 and HMB-45 staining was positive in 100% and 92% of the detected metastatic foci, respectively. The metastatic melanoma cells were epithelioid, spindled, and mixed in 86%, 5%, and 9% of cases. Metastatic foci were most often (86%) found in the subcapsular region of the SLN. Benign naevic cells were found coexisting in 14% of positive SLNs.

CONCLUSIONS

Staining for S100 is more sensitive than HMB-45 (100% v 92%), but HMB-45 staining helped to distinguish benign naevic cells from melanoma. The subcapsular region was crucial in SLN evaluation, because it contained the metastases in 86% of cases. Evaluation of the subcapsular space should not be compromised by cautery artefacts or incomplete excision of the SLN.

Dielectric relaxations in ultrathin isotactic PMMA films and PS-PMMA-PS trilayer films

The local and cooperative dynamics of supported ultrathin films ( L = 6.4 - 120 nm) of isotactic poly(methyl methacrylate) (i-PMMA, Mn = 118 x 10(3) g/mol) was studied using dielectric relaxation spectroscopy for a wide range of frequencies (0.1 Hz to 10(6) Hz) and temperatures (250 - 423 K). To assess the influence of the PMMA film surfaces on the glass transition dynamics, two different sample geometries were employed: a single layer PMMA film with the film surfaces in direct contact with aluminum films which act as attractive, hard boundaries; and a stacked polystyrene-PMMA-polystyrene trilayer film which contains diffuse PMMA-PS interfaces. For single layer films of i-PMMA, a decrease of the glass transition temperature T(g) by up to 10 K was observed for a film thickness L < 25 nm (comparable to R(EE)), indicated by a decrease of the peak temperature T(alpha) in the loss epsilon(")(T) at low and high frequencies and by a decrease in the temperature corresponding to the maximum in the apparent activation energy E(a)(T) of the alpha-process. In contrast, measurements of i-PMMA sandwiched between PS-layers revealed a slight (up to 5 K) increase in T(g) for PMMA film thickness values less than 30 nm. The slowing down of the glass transition dynamics for the thinnest PMMA films is consistent with an increased contribution from the less mobile PMMA-PS interdiffusion regions.

Peer review amongst restorative specialists on the quality of their communication with referring dental practitioners

OBJECTIVE

A peer review study was carried out to assess the written communication between consultants and specialist registrars in restorative dentistry with the referring general dental practitioners.

METHODS

Seven people took part in the study and each presented referral and reply letters for five patients whom they had seen for consultation. The referral letters were used for information only and were not used in the peer review process. Each participant inspected the referral and reply letters from the other six participants. The reply letters were anonymously peer reviewed by using a proforma containing agreed criteria in relation to appropriate factors to include in the reply letter. The reviewer also ranked the letter in relation to overall quality on a 1-10 point scale.

RESULTS

It was found that the participants' letters generally conformed positively with the agreed criteria although there were some differences between individuals. There were particular problems identified in relation to tooth notation. Reply letters commonly used different forms of tooth notation to the referring practitioners.

CONCLUSIONS

The ranking of the letters generally indicated that the participants' replies were judged to be favourable by their peers. There may be scope for continuing this study in relation to peer review by other groups of professionals, in particular practitioners in primary dental care.

An assessment of the incidence of punctures in latex and non-latex dental examination gloves in routine clinical practice

OBJECTIVE

To investigate the puncture resistance of a recently introduced non-latex, nitrile dental glove in comparison with a latex glove worn during routine clinical dental procedures.

SETTING

Dentists in general dental practice working within the UK during 1999.

SUBJECTS AND METHODS

2,020 gloves worn by five general dental practitioners were examined for punctures following standard clinical use by a water inflation method. Procedures undertaken during glove usage and length of time worn were recorded.

RESULTS

Following clinical use, 1.9% of the latex gloves and 5.3% of the nitrile gloves had punctures, a statistically significant difference (P < 0.0001). The puncture resistance of the nitrile gloves was superior to the puncture resistance of previously tested worn non-latex (vinyl) gloves. There was no evidence of a statistically significant difference between operators for the percentage or incidence of punctured gloves (P = 0.787) after correcting for glove type. No statistically significant difference was noted between incidence of puncture in the control, unused gloves (n = 200 for each type) and the gloves examined following clinical use (P = 0.907 for nitrile, P = 0.613 for latex).

CONCLUSION

No increase in the number of punctures was noted following clinical use for either glove type. This could be considered to indicate good puncture resistance of the gloves tested in clinical use.

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.

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.

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.

Interleukin-1 induces lipid peroxidation and membrane changes in rat hippocampus: An age-related study

BACKGROUND

The proinflammatory cytokine, interleukin-1, is traditionally associated with the immune response but recent evidence indicates that it plays a role in neuronal function. Its expression is increased in neurodegenerative conditions and preliminary evidence suggests that it is also increased with increasing age. Receptors for interleukin-1 are differentially distributed in the brain with a high density in the hippocampus, where interleukin-1beta exerts inhibitory effects on release and calcium channel function.

OBJECTIVE

The aim of this study was to investigate the possibility that interleukin-1 might lead to age-related changes in membrane composition.

METHODS

Lipid peroxidation was assessed in the presence or absence of interleukin-1beta in hippocampal tissue prepared from 4- and 22-month-old rats. These data were analysed in parallel with age-related changes in arachidonic acid and interleukin-1beta concentrations in the hippocampus.

RESULTS

We report that interleukin-1beta increased lipid peroxidation in hippocampal tissue prepared from 4- but not 22-month-old rats, and that this effect was inhibited by alpha-tocopherol. The attenuated response to interleukin-1beta in tissue prepared from aged rats correlated with increased expression of endogenous interleukin-1beta. Thus, using an ELISA, we have demonstrated an age-related increase in the concentration of interleukin-1beta, which is accompanied by an age-related decrease in membrane arachidonic acid.

CONCLUSION

We propose that increased interleukin-1beta expression impacts on membrane composition and therefore contributes to age-related impairments in neuronal function.

Procorticotrophin-releasing hormone: endoproteolytic processing and differential release of its derived peptides within AtT20 cells

Procorticotrophin-releasing hormone (proCRH) is expressed mainly in the hypothalamus and in the placenta, where it undergoes tissue-specific endoproteolysis. Our results show that within stably transfected AtT20/D16V cells proCRH is cleaved to generate two fragments of approximately 8 and 3 kDa which could account for proCRH(125-194) and proCRH(125-151), respectively, and a 4.5 kDa product which could account for mature IR-CRH(1-41). The immunofluorescence staining patterns for IR-CRH and IR-ACTH and their response of secretagogues indicate targeting of proCRH and POMC to the secretory pathway in transfected AtT20 cells. In this work, we have used a unique set of specific RIAs and IRMAs to the full length POMC and proCRH molecules and several products of endoproteolytic processing to assess if they could be released differentially in response to stimulation. Although the release of both IR-ACTH and IR-CRH peptides from transfected AtT20 cells is stimulated in response to exposure to high potassium stimulation (51 mM KCl/SmM CaCl2), the sorting index (SI) suggests that mature ACTH is sorted to the regulated secretory pathway 2.1-fold more efficiently than mature CRH(1-41). Mature ACTH is also sorted to the regulated secretory pathway 9-fold more efficiently than IR-proCRH(125-151). Also, mature CRH(1-41) is sorted to the regulated secretory pathway 3-fold more efficiently than IR-proCRH(125-151). These results therefore indicate that the intracellular mechanisms for the storage and release of POMC, proCRH and their endoproteolytic products differ and would sustain the hypothesis that within mammalian peptidergic cells, different biologically active peptides originating from the same or different precursor molecules, could be differentially released in response to specific stimuli. This would give these cells the capacity to finely regulate neurotransmitter release in response to environmental and physiological demands.

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.

Analysis of the effect of membrane arachidonic acid concentration on modulation of glutamate release by interleukin-1: an age-related study

Aging is associated with a change in membrane composition that includes a decrease in membrane polyunsaturated fatty acids, including arachidonic acid, and an increase in membrane cholesterol. Alterations in membrane structure are likely to impact on transmitter release, which relies on the fusion of synaptic plasma and synaptic vesicle membranes, and it may therefore be the underlying cause of the age-related decrease in glutamate release in hippocampal preparations. Recent evidence indicates that interleukin-1, by binding with its receptor, inhibits glutamate release in hippocampal synaptosomes prepared from young but not aged rats. The age-related attenuated effect may be due to impaired ligand-receptor interactions arising from the change in membrane composition, which should theoretically be reversed by increasing membrane polyunsaturated fatty acid concentration. To test this hypothesis, we have investigated the effect of a diet supplemented with arachidonic acid and its precursor, gamma-linolenic acid, on membrane arachidonic acid concentration, glutamate release and on the release response to interleukin-1 in hippocampal tissue prepared from aged and young rats. We report that dietary supplementation reversed the age-related changes in membrane arachidonic acid and expression of IL-1beta. We also present data that indicate that the age-related decrease in glutamate release from hippocampal synaptosomes was reversed in aged animals that had been fed on the experimental diet. The data support the view that changes in membrane composition contribute to certain age-related deficits, in particular the decrease in glutamate release observed in hippocampal synaptosomes.

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.

Evidence that increased hippocampal expression of the cytokine interleukin-1 beta is a common trigger for age- and stress-induced impairments in long-term potentiation

Several cytokines and their receptors are identified in brain; one of these is the proinflammatory cytokine interleukin-1beta that is synthesized and released from neurons and glia in response to stress or insult. Among the actions of interleukin-1beta is its ability to inhibit long-term potentiation in the hippocampus in vitro, an action that mimics one of the consequences of stress and age. It has been shown that the concentration of interleukin-1beta in brain tissue is increased in neurodegenerative conditions, and recent evidence from our laboratory has indicated an increase in the concentration of interleukin-1beta in the hippocampus of aged rats. These observations led us to consider that the underlying common cause of impaired long-term potentiation in aged and stressed rats might be increased endogenous interleukin-1beta concentration in hippocampus. The data presented here indicate that there was an inverse relationship between concentration of interleukin-1beta in the dentate gyrus and long-term potentiation in perforant path-->granule cell synapses in aged rats, stressed rats, and rats pretreated with interleukin-1beta. The evidence suggested that the cytokine induces formation of reactive oxygen species that triggers lipid peroxidation in vivo, as well as in vitro, and that these changes lead to depletion of membrane arachidonic acid that correlates with impaired long-term potentiation. We propose that three theories of aging, the glucocorticoid theory, the membrane theory, and the free radical theory, constitute three facets of age with one underlying trigger: an increase in the endogenous concentration of interleukin-1beta in hippocampus.

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.

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.

Corticotrophin-releasing hormone receptor type 1: generation and characterization of polyclonal antipeptide antibodies and their localization in pituitary cells and cortical neurones in vitro

Corticotrophin-releasing hormone (CRH) is a 41 amino acid neuropeptide which plays a major role in regulating the endocrine response to stress. CRH acts by first binding to specific receptors on the plasma membrane of target cells. A CRH receptor from a human corticotroph adenoma and rat brain has recently been cloned (CRH-R1). In this paper, we have chosen three different peptide sequences within the CRH-R1 molecule which bear no similarity to other members of this receptor subfamily (or indeed any known protein) and which are likely to be exposed on the surface of the native protein, for antibody production. Some of these fragments produced antipeptide antibodies of good titre which cross-reacted with the CRH-R1 receptor expressed in transiently transfected COS-7 cells and in tissue extracts from rat cerebellum, cortex, pituitary gland and human myometrium, both in Western blots and in liquid-phase radioimmunoassay. We used immunofluorescence techniques to localize the CRH receptor in transiently transfected COS-7 cells, primary cultures of rat anterior pituitary (AP) cells, the corticotroph-tumour cells AtT20 D16-16 and cortical neurons in primary culture. Our results indicate IR-CRH-R1 receptors have a punctate distribution on the plasma membrane of AP cells and AtT20 D16-16 cells. Whilst in AP cells their appearance is a fine punctate pattern, in AtT20 cells, they appear as large patches which could account for receptor clusters. Within primary cortical neurons, their distribution does not appear to be polarized. Our results suggest that distribution of CRH-R1 receptors within the different cell-types investigated depends not only on the amino acid sequence but also on cellular factors.

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.

Generation and characterization of an antiserum reactive with a proteolytic processing site within rat procorticotrophin-releasing hormone

In this paper we report the generation of an antibody specific for the cleavage site within procorticotrophin-releasing hormone (proCRH) at the N-terminus proCRH/CRH (1-41) junction. Using radioimmunoassay techniques were show that the antibody generated (781) cross-reacts specifically with the proCRH (137-150) Tyr fragment, corresponding to the cleavage site within the full length precursor molecule. The anti-cleavage site antibody does not crossreact with the endoproteolytic products originated from the CRH precursor molecule, i.e. CRH (1-41) or proCRH (125-151) or with any of the CRH-immunoreactive fragments tested i.e. CRH (36-41), CRH (1-20) and CRH (30-41). It also shows no cross-reactivity with CRH-related substances from other species, i.e. urotensin I (fish) and sauvagine (frog). The cleavage site antibody (781), recognizes the full length proCRH molecule in Western blotting and in liquid phase radioimmunoassay from transfected CHO-K1 cells expressing the full length pre-proCRH cDNA. Using immunofluorescence and immunoprecipitation techniques followed by SDS-PAGE and autoradiography, we confirm the presence of the intact CRH precursor molecule within the nucleus and the cytoplasm of stably transfected CHO-K1 cells expressing immunoreactive proCRH. The immunofluorescence studies using primary cultures of hypothalamic neurons, show that immunoreactive (IR) proCRH is localized within the perinuclear region and was also seen along the neuronal processes where it accumulates at their tips. Our results, therefore, show that this antibody will be an invaluable tool in the study of intracellular trafficking in relation to the endoproteolytic processing of the CRH precursor molecule.

Mitogenic effects and nuclear localisation of procorticotrophin-releasing hormone expressed within stably transfected fibroblast cells (CHO-K1)

To investigate the intracellular localisation and biological activity of procorticotrophin-releasing hormone (proCRH), we have established stably transfected CHO-K1 cells expressing the rat pre-proCRH cDNA. Using immunoblot analysis of cell lysates of transfected CHO-K1 cells, we detected a major CRH immunoreactive band with an apparent molecular weight of approximately 19 kDa. This 19 kDa band could account for full length proCRH molecule which has not undergone post-translational modifications. Metabolic labelling followed by immunoprecipitation, SDS-PAGE and autoradiography indicated that no endoproteolytic processing of proCRH takes place within the transfected CHO-K1 cells. Immunofluorescence staining localises the CRH precursor to both the cytoplasm and to the nucleus in transfected CHO-K1 cells. This result was confirmed using subcellular fractionation techniques on radiolabelled CHO-K1 cells expressing immunoreactive CRH. A major CRH-immunoreactive band of 19 kDa was detected both in the microsomal and secreted fractions, indicating the presence of proCRH within the secretory pathway of these cells. This was also evident in the nuclear fraction, therefore confirming the nuclear localisation of proCRH. Analysis of DNA concentration, cell number and DNA synthesis showed that stably transfected CHO-K1 cells expressing proCRH have a higher proliferation and DNA synthesis rate than wildtype CHO-K1 cells or CHO-K1 cells transfected with pEE14 alone. Our results therefore suggest a mitogenic role for the intact proCRH molecule within CHO-K1 cells. Furthermore, treatment of mouse corticotrophic tumour cells (AtT20/D16-16) with conditioned medium from transfected CHO-K1 cells expressing proCRH, stimulated both DNA synthesis and cell proliferation above basal levels. Our results constitute the first reported direct evidence of a mitogenic role for proCRH acting on a corticotrophic cell population.

Scale Transformation of Magnetic "Bubble" Arrays: Coupling of Topological Disorder and Polydispersity

The evolution of disorder in response to period adaptation in a hexagonal magnetic bubble array is shown to arise from the proliferation of dislocations and to proceed by means of intermediate states of steadily decreasing hexatic order to an amorphous final state. Remarkably, each dislocation core imposes a size adjustment on bubbles decorating its constituent pair of five- and sevenfold coordinated sites. Topological disorder thus induces intrinsic polydispersity and converts the initially unimodal size distribution into a trimodal one. This intimate interplay between geometry and topology provides an explicit mechanism by which structural disorder arises as a result of frustration.

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.