Age-associated changes in the blood-brain barrier: comparative studies in human and mouse.

AIMS: While vascular pathology is a common feature of a range of neurodegenerative diseases, we hypothesized that vascular changes occur in association with normal ageing. Therefore, we aimed to characterize age-associated changes in the blood-brain barrier (BBB) in human and mouse cohorts. METHODS: Immunohistochemistry and Evans blue assays were used to characterize BBB dysfunction (tight junction protein expression and serum plasma protein accumulation), vascular pathology (pericyte loss and vascular density) and glial pathology (astrocyte and microglial density) in ageing neurological control human prefrontal cortex (a total of 23 cases from 5 age groups representing the spectrum of young adult to old age: 20-30 years, 31-45 years, 46-60 years, 61-75 years and 75+) and C57BL/6 mice (3 months, 12 months, 18 months and 24 months, n = 5/6 per group). RESULTS: Quantification of the tight junction protein ZO-1 within the cortex and cerebellum of the mouse cohort showed a significant trend to both increased number (cortex P < 0.001, cerebellum P < 0.001) and length (cortex P < 0.001, cerebellum P < 0.001) of junctional breaks associated with increasing age. GFAP expression significantly correlated with ageing in the mice (P = 0.037). In the human cohort, assessment of human protein accumulation (albumin, fibrinogen and human IgG) demonstrated cells morphologically resembling clasmatodendritic astrocytes, indicative of BBB dysfunction. Semiquantitative assessment of astrogliosis in the cortex expression revealed an association with age (P = 0.003), while no age-associated changes in microglial pathology, microvascular density or pericyte coverage were detected. CONCLUSIONS: This study demonstrates BBB dysfunction in normal brain ageing, both in human and mouse cohorts.

Stalled replication forks within heterochromatin require ATRX for protection.

Expansive growth of neural progenitor cells (NPCs) is a prerequisite to the temporal waves of neuronal differentiation that generate the six-layered neocortex, while also placing a heavy burden on proteins that regulate chromatin packaging and genome integrity. This problem is further reflected by the growing number of developmental disorders caused by mutations in chromatin regulators. ATRX gene mutations cause a severe intellectual disability disorder (α-thalassemia mental retardation X-linked (ATRX) syndrome; OMIM no. 301040), characterized by microcephaly, urogenital abnormalities and α-thalassemia. Although the ATRX protein is required for the maintenance of repetitive DNA within heterochromatin, how this translates to disease pathogenesis remain poorly understood and was a focus of this study. We demonstrate that Atrx(FoxG1Cre) forebrain-specific conditional knockout mice display poly(ADP-ribose) polymerase-1 (Parp-1) hyperactivation during neurogenesis and generate fewer late-born Cux1- and Brn2-positive neurons that accounts for the reduced cortical size. Moreover, DNA damage, induced Parp-1 and Atm activation is elevated in progenitor cells and contributes to their increased level of cell death. ATRX-null HeLa cells are similarly sensitive to hydroxyurea-induced replication stress, accumulate DNA damage and proliferate poorly. Impaired BRCA1-RAD51 colocalization and PARP-1 hyperactivation indicated that stalled replication forks are not efficiently protected. DNA fiber assays confirmed that MRE11 degradation of stalled replication forks was rampant in the absence of ATRX or DAXX. Indeed, fork degradation in ATRX-null cells could be attenuated by treatment with the MRE11 inhibitor mirin, or exacerbated by inhibiting PARP-1 activity. Taken together, these results suggest that ATRX is required to limit replication stress during cellular proliferation, whereas upregulation of PARP-1 activity functions as a compensatory mechanism to protect stalled forks, limiting genomic damage, and facilitating late-born neuron production.

Transfusion associated circulatory overload: a critical incident.

Transfusion associated circulatory overload (TACO) is a serious but under-recognised complication of blood transfusion. While the exact incidence rate is unknown the associated morbidity and mortality make this a transfusion reaction worthy of attention. This article provides details of a critical incident involving TACO followed by a literature review and discussion written from the perspective of a student ODP. The goal of this article is to raise awareness of TACO amongst hospital staff to facilitate faster recognition and earlier intervention in future events.

Lack of unique neuropathology in amyotrophic lateral sclerosis associated with p.K54E angiogenin (ANG) mutation.

AIMS: Five to 10% of cases of amyotrophic lateral sclerosis are familial, with the most common genetic causes being mutations in the C9ORF72, SOD1, TARDBP and FUS genes. Mutations in the angiogenin gene, ANG, have been identified in both familial and sporadic patients in several populations within Europe and North America. The aim of this study was to establish the incidence of ANG mutations in a large cohort of 517 patients from Northern England and establish the neuropathology associated with these cases. METHODS: The single exon ANG gene was amplified, sequenced and analysed for mutations. Pathological examination of brain, spinal cord and skeletal muscle included conventional histology and immunohistochemistry. RESULTS: Mutation screening identified a single sporadic amyotrophic lateral sclerosis case with a p.K54E mutation, which is absent from 278 neurologically normal control samples. The clinical presentation was of limb onset amyotrophic lateral sclerosis, with rapid disease progression and no evidence of cognitive impairment. Neuropathological examination established the presence of characteristic ubiquitinated and TDP-43-positive neuronal and glial inclusions, but no abnormality in the distribution of angiogenin protein. DISCUSSION: There is only one previous report describing the neuropathology in a single case with a p.K17I ANG mutation which highlighted the presence of eosinophilic neuronal intranuclear inclusions in the hippocampus. The absence of this feature in the present case indicates that patients with ANG mutations do not always have pathological changes distinguishable from those of sporadic amyotrophic lateral sclerosis.

The estimation of approximate sample size requirements necessary for clinical and epidemiological studies in vision sciences.

PURPOSE: The aim of this paper is to provide an overview of sample size estimations for the most frequent type of group studies that result in continuous, binary and ordered categorical outcomes. METHODS: The theory behind power and sample size calculations is explained using the basic probability concepts that underpin the most frequently used statistical significance tests. RESULTS: Simple formulae and tables are presented for the estimation of sample sizes necessary for efficient and effective clinical and epidemiological trials. These may be used without recourse to sophisticated and complex computer software packages. Mathematical complexity is kept to a minimum. Examples and applications from the vision sciences are specifically highlighted. CONCLUSIONS: The paper highlights, with practical examples, the concepts and computations necessary to make sample size estimations accessible to all eye professionals involved in research, diagnostic and statutory work.

Concordance between common dry eye diagnostic tests.

AIM: Large variations in results of diagnostic tests for mild to moderate dry eye are widely recognised. The purpose of this study was to assess if there was concordance between common dry eye diagnostic tests. METHODS: A total of 91 subjects were recruited to the study. The tear film and ocular surface were evaluated using the phenol red thread test (PRT), tear film break-up time (TBUT), biomicroscopic examination and impression cytological assessment of conjunctival goblet cells. Dry eye symptoms were assessed using McMonnies' dry eye questionnaire (MQ) and statistical correlations between all tests were assessed. RESULTS: This study cohort did not include severe aqueous deficient dry eye patients as determined by the PRT. A statistically significant difference was noted between PRT results and all other tests (p

A retrospective audit of the extent and nature of domestic violence cases identified over a three year period in the two district command units of the police service of Northern Ireland.

The work load of forensic medical officers (FMOs) who provide medical cover for the Coleraine and Limavady district command units (DCU) of the police service of Northern Ireland (PSNI) in dealing with domestic violence was investigated over a three year period from 1st April 2003 to 31st March 2006. A total of 128 cases involving domestic violence were identified during this three year period. There was a significant increase from 4% (32/791) in the first year to 6.6% (56/851, p<0.01) in the number of cases of identified domestic violence in the second year which dropped to 4.2% (40/956) in the third year. Victims were identified in 38% of these domestic violence cases with 62% being identified as assailants. It was noted that there was a significant difference in the proportion of male assailants (96.2%) from female assailants (3.8%). Fifty-four percent of victims were noted to have injuries in accordance with the more serious injury categories of assault of actual bodily harm (AOABH) and grievous bodily harm (GBH). Domestic incidents occurred at the home in 91% of cases, with the FMO being the primary contact in 97% of cases. Alcohol was implicated in 56% of all domestic violence cases recorded.

Increased serum ferritin levels in amyotrophic lateral sclerosis (ALS) patients.

Iron misregulation promotes oxidative stress, a proposed pathological mechanism in neurodegenerative disease. The aim of this study was to evaluate serum iron metabolism indicators in 60 amyotrophic lateral sclerosis (ALS) patients and 44 age matched controls. Serum ferritin levels were significantly increased in ALS patients compared to controls (p < 0.001), while no differences in the levels of serum iron, transferrin, iron saturation or total iron binding capacity were found. Likewise no differences in C reactive protein (CRP) or caeruloplasmin were detected, suggesting that the elevated ferritin levels in ALS did not merely indicate an acute phase response. The increased ferritin level may reflect a general increase in stored iron or be a consequence of ongoing muscle degeneration.

Association of the H63D polymorphism in the hemochromatosis gene with sporadic ALS.

Iron misregulation promotes oxidative stress and abnormally high iron levels have been found in the spinal cords of patients with ALS. The authors investigated whether HFE gene polymorphisms, linked to hemochromatosis, are associated with ALS using two independent populations of patients with sporadic ALS and controls (totaling 379 patients and 400 controls). They found that the H63D polymorphism is overrepresented in individuals with sporadic ALS (odds ratio 1.85, CI: 1.35 to 2.54).

Antibody responses of naive cattle to two inactivated bovine viral diarrhoea virus vaccines, measured by indirect and blocking ELISAS and virus neutralisation.

Two groups of naive heifers were given primary courses of two inactivated bovine viral diarrhoea (BVD) virus vaccines licensed for use in the UK. Their humoral responses in serum and milk were assayed by means of an indirect ELISA detecting antibodies to structural viral glycoproteins, a blocking ELISA specific for antibodies to the non-structural protein NS2-3 and the virus neutralisation test (VNT). For each assay, the numbers of serum or milk samples testing positive at each sample point and the mean values were determined. In both vaccine groups, serum antibody responses were detected by the indirect ELISA and the VNT, with both the numbers of seropositive animals and mean values peaking five weeks after the second vaccination. In the 23 heifers vaccinated with Bovilis BVD, the mean NS2-3-specific ELISA values remained low throughout the trial, with no serum or milk samples testing positive. In the 24 heifers vaccinated with Bovidec, the mean NS2-3 responses peaked below the level of positivity five weeks after the second vaccination, before declining again; NS2-3-specific antibodies were detected in one serum sample and one milk sample from two heifers in this group. A pooled milk sample from each vaccine group tested negative by both ELISAS 12 weeks after the second vaccination.

Risk factors for toxic mastitis in cows.

A case-control study of the management and disease risk factors associated with toxic mastitis in cows was carried out. Seventy-one cases satisfied all the selection criteria, and a subset of 41 cases in which pure growths of Escherichia coil were cultured from milk samples was also investigated. Conditional multiple logistic regression analysis of the 71 cases and matched controls revealed no statistically significant associations. However, among the subset of 41 cases and matched controls, the administration of calcium parenterally at calving (P < 0.01) and assistance at calving (P < 0.01) were both associated with toxic mastitis. Controlling for assistance at calving, the odds of a cow developing E coli toxic mastitis if it had received calcium parenterally at calving were 23 times higher than for a cow that had not received calcium. Similarly, controlling for the administration of calcium at calving, the odds of a cow developing E coli toxic mastitis if it had received assistance at calving were 11 times higher than for a cow that did not receive assistance.

A framework for developing excellence as a clinical educator.

The current emphasis on providing quality undergraduate and postgraduate medical education has focused attention on the educational responsibilities of all doctors. There is a greater awareness of the need to train doctors as educators and courses have been set up to satisfy this need. Some courses, such as those on how to conduct appraisal, are specific to one task facing a medical educator. Other courses take a broader view and relate educational theory to practice. In this paper we describe an outcome-based approach in which competence in teaching is defined in terms of 12 learning outcomes. The framework provides a holistic approach to the roles of the teacher and supports the professionalism of teaching. Such a framework provides the basis for the development of a curriculum for teaching excellence. It helps to define important competences for different categories of teachers, communicate the areas to be addressed in a course, identify gaps in course provision, evaluate courses, assist in staff planning and allow individuals to assess their personal learning needs. The framework is presented to encourage wider debate.

Aspects of the epizootiology of pancreas disease in farmed Atlantic salmon Salmo salar in Ireland.

A computerised database containing information on over 17.8 million salmon contained within 49 separate marine populations was used to study the epidemiology of pancreas disease (PD) in Ireland. Of the 43 recorded PD outbreaks, 57% occurred in the 3 mo period August to October inclusive (17 to 32 wk post-transfer). Analysis of variance of mortality rates during PD outbreaks occurring on 6 marine sites over a 5 yr period showed that mortality rates vary significantly between sites (p < 0.001) but not between years over this time period. The mortality rate during PD outbreaks ranged from 0.1 to 63%. Mortality rates were significantly higher when PD outbreaks occurred earlier in the year (y = -1.28x + 59, SE of b 0.33). The mean length of a PD outbreak was 112 d (SE = 7.7, n = 37). There was no correlation between PD mortality rate and smolt input weight, initial stocking density and transfer mortality.

An update on the epidemiology of contact dermatitis in commercial broilers.

A computerized management and disease information retrieval system for commercial broiler production was established in 1985. The database presently contains information on over 950 flocks (15 million birds) per annum. The system has enabled the effectiveness of strategies which have been implemented to control contact dermatitis to be monitored. Between 1986 and 1994, the prevalence of breast burn lesions has been practically eradicated (0.2 to 0.00%) and the prevalence of hock burn lesions has been dramatically reduced from 21 to 7%. This reduction has been mainly due to the use of better litter management techniques and improvements in house design, particularly changing the type of drinker system. Production factors during 1993 and 1994 which were found to be consistently related to increased prevalence of hock burn lesions were male only flocks, inferior food conversion ratio, failure to meet target income and increased mortality rates.

5-HT2C receptor activation decreases appetite and body weight in obese subjects.

We studied the effect of 2 weeks administration of the 5-HT2C receptor agonist, m-chlorophenylpiperazine (mCPP), on appetite and body weight in 18 moderately obese subjects in a double-blind, placebo-controlled trial, mCPP caused a small but significant (0.75 kg) reduction in body weight and in subjective ratings of hunger. Plasma prolactin was significantly elevated by the final dose of mCPP. Our data suggest that during 2 weeks treatment in humans, mCPP may continue to activate brain 5-HT2C receptors, and that this effect is associated with decreases in appetite and body weight.

Sumatriptan decreases food intake and increases plasma growth hormone in healthy women.

We studied the effect of the 5-HT1B/ID receptor agonist sumatriptan (6 mg s.c.) on plasma growth hormone and prolactin and food intake in 15 healthy female subjects using a double-blind, placebo-controlled, cross-over design. Sumatriptan significantly elevated plasma growth hormone but did not alter plasma prolactin. Sumatriptan also significantly lowered total food intake in a buffet meal, particularly decreasing the intake of fat. Our results indicate that 5-HT1B/ID receptors may be involved in the regulation of food intake in humans. In addition, while activation of 5-HT1B/ID receptors stimulates growth hormone release in both men and women, sumatriptan lowers plasma prolactin only in men, suggesting sex differences in the 5-HT regulation of prolactin release.

Position-selective activation of peripheral nerve fibers with a cuff electrode.

The degree of spatial selectivity which can be obtained with longitudinal dot tripoles in an insulating cuff was quantified in terms of the overlap between fiber populations activated by different tripoles. Previous studies have failed to take into account the relative influences of transverse current and longitudinal current on position-selective activation, and furthermore have not controlled for the differing sensitivities of large and small nerve fibers to electrical stimuli. In this study, these factors were taken into account. Transverse current from an anode positioned opposite the stimulating cathode was found to improve spatial selectivity, and selectivity was enhanced when the ratio of transverse current to longitudinal current was increased. Large fibers were excited before small fibers, irrespective of fiber position, indicating a combination of position and size selectivity.

Stillbirth/perinatal weak calf syndrome: a study of calves with an abnormal thyroid gland.

Data collected from 365 calves dead from stillbirth/perinatal weak calf syndrome were analysed to determine the predictive value of thyroid gland weight as an indicator of abnormality of the thyroid gland, and to examine the relationships between abnormality of the thyroid gland and other findings in the calves and also the parity of the dam. There was a significant relationship (P < 0.001) between the thyroid gland weight and bodyweight for the calves with a histologically normal thyroid gland, but there was no such relationship for calves with an abnormal thyroid gland. Only 1.1 per cent of the histologically normal thyroid glands weighed more than 30 g, indicating that there is a very high probability that glands weighing more than 30 g are abnormal. However, 76.0 per cent of moderately to severely affected glands weighed less than 30 g. The following significant differences between calves with an abnormal and those with a normal thyroid gland were established. Abnormal thyroid glands were significantly heavier (P < 0.01), constituted a significantly greater percentage of the calf's bodyweight (P < 0.01) and had a significantly lower iodine concentration (P < 0.001). A significantly higher proportion of calves with an abnormal thyroid gland had uninflated lungs (P < 0.01), and a significantly higher proportion had pneumonia (P < 0.01). Abnormal thyroid glands were associated with a low selenium concentration in the kidneys. There were no associations between abnormalities of the thyroid gland and the parity of the dam, the presence of skeletal fractures, the weight or sex of the calf, infection with leptospira, Salmonella dublin, Bacillus species, Actinomyces pyogenes or Aspergillus species, the quantities of hepatic iron pigment, liver vitamin E concentration or serum cholesterol concentration.

The effects of D- and L-fenfluramine (and their interactions with D-amphetamine) on psychomotor function and mood.

This study reports the results on psychomotor functioning of D- and L-fenfluramine alone, and in combination with D-amphetamine, in a placebo-controlled trial on 12 normal male volunteers, in order to investigate their CNS activity in humans. The major findings were that D-amphetamine increased alertness, L-fenfluramine increased unhappiness whilst D-fenfluramine decreased hunger and increased the critical flicker fusion threshold. D-Amphetamine in combination with D-fenfluramine increased the critical flicker fusion threshold and in combination with L-fenfluramine the alerting action was diminished. The differing actions of the fenfluramine isomers and their interactions with D-amphetamine suggest that D-fenfluramine is predominantly serotonergic in its activity, whereas L-fenfluramine may be causing dopamine blockade, reducing certain actions of amphetamine possibly mediated by dopamine receptors. The significance of these results in relationship to the psychopharmacology of serotonin, dopamine, and noradrenaline is discussed.