Two separate, large cohorts reveal potential modifiers of age-associated variation in visual reaction time performance

To identify potential factors influencing age-related cognitive decline and disease, we created MindCrowd. MindCrowd is a cross-sectional web-based assessment of simple visual (sv) reaction time (RT) and paired-associate learning (PAL). svRT and PAL results were combined with 22 survey questions. Analysis of svRT revealed education and stroke as potential modifiers of changes in processing speed and memory from younger to older ages (n_total = 75,666, n_women = 47,700, n_men = 27,966; ages 18-85 years old, mean (M)_Age = 46.54, standard deviation (SD)_Age = 18.40). To complement this work, we evaluated complex visual recognition reaction time (cvrRT) in the UK Biobank (n_total = 158,249 n_women = 89,333 n_men = 68,916; ages 40-70 years old, M_Age = 55.81, SD_Age = 7.72). Similarities between the UK Biobank and MindCrowd were assessed using a subset of MindCrowd (UKBb MindCrowd) selected to mirror the UK Biobank demographics (n_total = 39,795, n_women = 29,640, n_men = 10,155; ages 40-70 years old, M_Age = 56.59, SD_Age = 8.16). An identical linear model (LM) was used to assess both cohorts. Analyses revealed similarities between MindCrowd and the UK Biobank across most results. Divergent findings from the UK Biobank included (1) a first-degree family history of Alzheimer's disease (FHAD) was associated with longer cvrRT. (2) Men with the least education were associated with longer cvrRTs comparable to women across all educational attainment levels. Divergent findings from UKBb MindCrowd included more education being associated with shorter svRTs and a history of smoking with longer svRTs from younger to older ages.

Smoking is associated with impaired verbal learning and memory performance in women more than men

Vascular contributions to cognitive impairment and dementia (VCID) include structural and functional blood vessel injuries linked to poor neurocognitive outcomes. Smoking might indirectly increase the likelihood of cognitive impairment by exacerbating vascular disease risks. Sex disparities in VCID have been reported, however, few studies have assessed the sex-specific relationships between smoking and memory performance and with contradictory results. We investigated the associations between sex, smoking, and cardiovascular disease with verbal learning and memory function. Using MindCrowd, an observational web-based cohort of ~ 70,000 people aged 18-85, we investigated whether sex modifies the relationship between smoking and cardiovascular disease with verbal memory performance. We found significant interactions in that smoking is associated with verbal learning performance more in women and cardiovascular disease more in men across a wide age range. These results suggest that smoking and cardiovascular disease may impact verbal learning and memory throughout adulthood differently for men and women.

"You Are Beautiful, No Matter What They Say": Applying An Evidence-Based Approach To Body Image Law

Israeli and French Governments passed Body Image Laws that require models to have a minimum BMI or be of a healthy weight and if an image was modified to make the model appear thinner, it must have a warning. Are these laws merely symbolic, to focus a spotlight on this issue, or can they too have an impact? This article analyses some of the criticisms of the Body Image Laws by applying existing evidence from health research. Ultimately, it argues that there are many flaws with the Body Image Laws and that such a law should not be passed in Australia.

Membrane Plasma Fractionation: Effect of the Surface Area

The influence of the surface area on the performance of plasma filters for dead-end mode of filtration is presented in this paper.

Theoretical analysis of the dead-end filtration was performed and verified experimentally (using ENKA cellulose-diacetate PF-100 membranes) in respect to β-lipoprotein. The theoretical model allows to optimize the course of the transmembrane pressure during plasma fractionation procedure in dependence of the surface area, initial concentration of macromolecules, total volume of the feed and membrane structure. The results indicate that the surface area effect is an important factor in the operation of membrane plasma fractionation and should be considered in the design of the plasma fractionation filter.

First outbreak of colonization by linezolid- and glycopeptide-resistant Enterococcus faecium harbouring the cfr gene in a UK nephrology unit

AIM

To describe an outbreak of colonization by linezolid- and glycopeptide-resistant Enterococcus faecium harbouring the cfr gene in a UK nephrology unit.

METHODS

Isolates of linezolid-resistant E. faecium were typed by pulsed-field gel electrophoresis (PFGE), and examined by polymerase chain reaction (PCR) and sequencing for the transmissible cfr gene that confers resistance to linezolid. Enhanced environmental cleaning, initial and weekly screening of all patients, and monitoring of adherence to standard infection control precautions were implemented.

FINDINGS

Five patients with pre-existing renal disease were found to have rectal colonization with linezolid-resistant E. faecium over a two-week period. The index case was a 57-year-old male from India who had travelled to the UK. One patient also had a linezolid-resistant E. faecium of a different PFGE profile isolated from a heel wound. All isolates were confirmed to harbour the cfr gene by PCR and Sanger sequencing, and all were resistant to glycopeptides (VanA phenotype).

CONCLUSIONS

This article describes the first UK outbreak with a single strain of linezolid- and glycopeptide-resistant E. faecium harbouring the cfr gene, affecting five patients in a nephrology unit. Following the implementation of aggressive infection control measures, no further cases were detected beyond a two-week period.

Selecting for a sustainable workforce to meet the future healthcare needs of rural communities in Australia

An undersupply of generalists doctors in rural communities globally led to widening participation (WP) initiatives to increase the proportion of rural origin medical students. In 2002 the Australian Government mandated that 25% of commencing Australian medical students be of rural origin. Meeting this target has largely been achieved through reduced standards of entry for rural relative to urban applicants. This initiative is based on the assumption that rural origin students will succeed during training, and return to practice in rural locations. One aim of this study was to determine the relationships between student geographical origin (rural or urban), selection scores, and future practice intentions of medical students at course entry and course exit. Two multicentre databases containing selection and future practice preferences (location and specialisation) were combined (5862), representing 54% of undergraduate medical students commencing from 2006 to 2013 across nine Australian medical schools. A second aim was to determine course performance of rural origin students selected on lower scores than their urban peers. Selection and course performance data for rural (461) and urban (1431) origin students commencing 2006-2014 from one medical school was used. For Aim 1, a third (33.7%) of rural origin students indicated a preference for future rural practice at course exit, and even fewer (6.7%) urban origin students made this preference. Results from logistic regression analyses showed significant independent predictors were rural origin (OR 4.0), lower Australian Tertiary Admissions Rank (ATAR) (OR 2.1), or lower Undergraduate Medical and Health Sciences Admissions Test Section 3 (non-verbal reasoning) (OR 1.3). Less than a fifth (17.6%) of rural origin students indicated a preference for future generalist practice at course exit. Significant predictors were female gender (OR 1.7) or lower ATAR (OR 1.2), but not rural origin. Fewer (10.5%) urban origin students indicated a preference for generalist practice at course exit. For Aim 2, results of Mann-Whitney U tests confirmed that slightly reducing selection scores does not result in increased failure, or meaningfully impaired performance during training relative to urban origin students. Our multicentre analysis supports success of the rural origin WP pathway to increase rural student participation in medical training. However, our findings confirm that current selection initiatives are insufficient to address the continuing problem of doctor maldistribution in Australia. We argue for further reform to current medical student selection, which remains largely determined by academic meritocracy. Our findings have relevance to the selection of students into health professions globally.

A cross-sectional study exploring the different roles of individual and group assessment methods in assessing public health nutrition competence

BACKGROUND

Competency in the practice of public health is essential for dietitians, yet little is known about credible and dependable assessment in this field. The present study aimed to investigate the role of individual and group assessment tasks as elements of a public health nutrition competency-based assessment system.

METHODS

Assessment performance data from 158 dietetics students (three group tasks and one individual task) who had completed a practical placement learning experience in a public health nutrition setting were examined using nonparametric techniques. All 158 students were deemed individually 'competent' on completion of the placement.

RESULTS

The median mark was significantly lower for the individual compared to the group task, with a greater range of marks achieved in the individual assessment. There was a weak relationship between individual and group marks for the whole cohort (n = 158) (Spearman's rho correlation coefficient = 0.193, P = 0.015). Bland-Altman analysis showed that the mean (SD) agreement between the two assessment tasks was -5.9 (17.7) marks. Systematic bias between the two tasks was also demonstrated, indicating that students with the lowest average mark of the two assessments scored lower on the individual assessment task compared to their group task and those who had a higher average mark scored higher on the individual group assessment compared to their group task.

CONCLUSIONS

Student performance in public health differs between individual and group assessment. Individual assessment appears to differentiate between students, yet group work is essential for the development of teamwork skills. Both should be considered in the judgement of public health nutrition competency.

Why babies - what Australian mothers say

Earlier studies, mostly overseas, have explored the reasoning and thought processes underlying women's desires to conceive. A retrospective qualitative study was conducted to explore the motivations and anxieties of an Australian sample of women proceeding to a pregnancy and to explore their decision-making process. Twenty women over 18 years old who had one or more successful pregnancies and were recruited from a tertiary centre and private clinics, completed a questionnaire and a semi-structured interview. Thematic analysis was applied to the data. Multiple factors motivated women to proceed to a pregnancy and including influences arising from society or existing personal relationships, goals and desired experiences for parenthood and innate drives and reproductive related issues. The motivations of an urban Australian sample to proceed to a pregnancy differed little from studies elsewhere. This knowledge may assist in dealing with the concerns that underlie any pregnancy allowing for better obstetric management.

Why babies - What Australian mothers say

Earlier studies, mostly overseas, have explored the reasoning and thought processes underlying women's desires to conceive. A retrospective qualitative study was conducted to explore the motivations and anxieties of an Australian sample of women proceeding to a pregnancy and to explore their decision-making process. Twenty women over 18 years old who had one or more successful pregnancies and were recruited from a tertiary centre and private clinics, completed a questionnaire and a semi-structured interview. Thematic analysis was applied to the data. Multiple factors motivated women to proceed to a pregnancy and including influences arising from society or existing personal relationships, goals and desired experiences for parenthood and innate drives and reproductive related issues. The motivations of an urban Australian sample to proceed to a pregnancy differed little from studies elsewhere. This knowledge may assist in dealing with the concerns that underlie any pregnancy allowing for better obstetric management.

Meta-analysis: aerobic exercise for the treatment of anxiety disorders

BACKGROUND

This meta-analysis investigates the efficacy of exercise as a treatment for DSM-IV diagnosed anxiety disorders.

METHODS

We searched PubMED and PsycINFO for randomized, controlled trials comparing the anxiolytic effects of aerobic exercise to other treatment conditions for DSM-IV defined anxiety disorders. Seven trials were included in the final analysis, totaling 407 subjects. The control conditions included non-aerobic exercise, waitlist/placebo, cognitive-behavioral therapy, psychoeducation and meditation. A fixed-effects model was used to calculate the standardized mean difference of change in anxiety rating scale scores of aerobic exercise compared to control conditions. Subgroup analyses were performed to examine the effects of (1) comparison condition; (2) whether comparison condition controlled for time spent exercising and (3) diagnostic indication.

RESULTS

Aerobic exercise demonstrated no significant effect for the treatment of anxiety disorders (SMD=0.02 (95%CI: -0.20-0.24), z = 0.2, p = 0.85). There was significant heterogeneity between trials (χ(2) test for heterogeneity = 22.7, df = 6, p = 0.001). The reported effect size of aerobic exercise was highly influenced by the type of control condition. Trials utilizing waitlist/placebo controls and trials that did not control for exercise time reported large effects of aerobic exercise while other trials report no effect of aerobic exercise.

CONCLUSIONS

Current evidence does not support the use of aerobic exercise as an effective treatment for anxiety disorders as compared to the control conditions. This remains true when controlling for length of exercise sessions and type of anxiety disorder. Future studies evaluating the efficacy of aerobic exercise should employ larger sample sizes and utilize comparison interventions that control for exercise time.

Mobile hydrocarbon microspheres from >2-billion-year-old carbon-bearing seams in the South African deep subsurface

By ~2.9 Ga, the time of the deposition of the Witwatersrand Supergroup, life is believed to have been well established on Earth. Carbon remnants of the microbial biosphere from this time period are evident in sediments from around the world. In the Witwatersrand Supergroup, the carbonaceous material is often concentrated in seams, closely associated with the gold deposits and may have been a mobile phase 2 billion years ago. Whereas today the carbon in the Witwatersrand Supergroup is presumed to be immobile, hollow hydrocarbon spheres ranging in size from <1 μm to >50 μm were discovered emanating from a borehole drilled through the carbon-bearing seams suggesting that a portion of the carbon may still be mobile in the deep subsurface. ToF-SIMS and STXM analyses revealed that these spheres contain a suite of alkane, alkenes, and aromatic compounds consistent with the described organic-rich carbon seams within the Witwatersrand Supergroup's auriferous reef horizons. Analysis by electron microscopy and ToF-SIMS, however, revealed that these spheres, although most likely composed of biogenic carbon and resembling biological organisms, do not retain any true structural, that is, fossil, information and were formed by an abiogenic process.

Sex differences in angiotensin II- induced hypertension

Sex differences in the development of hypertension and cardiovascular disease have been described in humans and in animal models. In this paper we will review some of our studies which have as their emphasis the examination of the role of sex differences and sex steroids in modulating the central actions of angiotensin II (ANG II) via interactions with free radicals and nitric oxide, generating pathways within brain circumventricular organs and in central sympathomodulatory systems. Our studies indicate that low-dose infusions of ANG II result in hypertension in wild-type male mice but not in intact wild-type females. Furthermore, we have demonstrated that ANG II-induced hypertension in males is blocked by central infusions of the androgen receptor antagonist, flutamide, and by central infusions of the superoxide dismutase mimetic, tempol. We have also found that, in comparison to females, males show greater levels of intracellular reactive oxygen species in circumventricular organ neurons following long-term ANG II infusions. In female mice, ovariectomy, central blockade of estrogen receptors or total knockout of estrogen a receptors augments the pressor effects of ANG II. Finally, in females but not in males, central blockade of nitric oxide synthase increases the pressor effects of ANG II. Taken together, these results suggest that sex differences and estrogen and testosterone play important roles in the development of ANG II-induced hypertension.

In vivo neurogenesis in the dorsal vagal complex of the adult rat brainstem

The dorsal vagal complex (DVC) encompasses the nucleus tractus solitarii (NTS), the dorsal motor nucleus of the vagus nerve (DMX) and the area postrema (AP), that altogether provide the major integrative center for the mammalian autonomic nervous system. The adult rat DVC has been reported to contain afferent-dependent concentration of the plasticity-promoting polysialylated form of neural cell adhesion molecule [J Neurosci 21 (2001) 4721; Eur J Neurosci 14 (2001) 1194]. This prompted us to assess the occurrence of neurogenesis in the DVC of adult rats. Cumulative in vivo labeling of cell proliferation with i.p. bromodeoxyuridine (BrdU) injections was combined with phenotypic markers and confocal microscopy on serial brainstem sections throughout the DVC extent. In basal condition, sparse BrdU+ nuclei were selectively detected in the DVC according to a discrete and reproducible pattern. Some of them were found to colocalize with the neuronal markers doublecortin, HuC/D, or neuronal-specific antigen (NeuN), demonstrating that neurogenesis does occur within the DVC of adult rat. In the NTS, 10% of the BrdU+ nuclei were also NeuN+. A comparable proportion of astrogliogenesis was found in the DVC. Nestin immunohistochemistry yielded a highly specific labeling pattern at the border between AP and NTS. These data may relate to the neural stem cells that have been reported in the floor of the IVth ventricle [J Neurosci 16 (1996) 7599]. In order to assess a possible modulation of neurogenesis by afferent input in vivo, unilateral vagotomy was performed prior to cumulative BrdU treatment. Such DVC deafferentation triggered a large increase of BrdU incorporation in the ipsilateral DVC, which was associated with microglial proliferation in the DMX and with increased genesis of neurons and astrocytes in the NTS. These findings establish DVC as a novel model of adult neurogenesis that is reactive to deafferentation.

Patient outcomes after peripheral revascularization surgery

Acquired peripheral vascular disease (PVD) is a significant problem in the United States, resulting in both morbidity and mortality. The purpose of the pilot study was to determine patient outcomes after peripheral revascularization surgery. The specific aims of the pilot study were to examine peripheral revascularization surgical patient outcomes (PVD-related clinical symptoms, functioning, atherosclerotic disease risk factor reduction, and patient satisfaction) and to determine the influence of selected patient demographic characteristics (gender, age) on selected patient outcomes (PVD-related clinical symptoms, functioning, atherosclerotic disease risk factor reduction, and patient satisfaction). A prospective, repeated measures design was used for the study. A total of 39 patients, 18 women and 21 men, participated in the study, with a mean age of 68.86 years (SD = 13.61). The average length of hospitalization after surgery was 4.05 days. At 1 month after discharge, the majority of patients had relief from claudication and paresthesia. In regard to outcomes related to atherosclerotic risk factor modification, patients reported that they exercised on a routine basis, an average of 5.31 +/- 1.97 times per week. Before surgery, 21 patients reported that they smoked; 6 patients reported that they continued to smoke at follow-up. There were no significant differences in mean total scores of atherosclerotic risk modification by either gender or age groups (<65 or > or =65 years) with the use of one-way analyses of variance (ANOVAs). By using a Likert scale (ie, 0 to 10), the mean level of functioning was 8.18 +/- 2.76, with women having significantly higher mean levels of functioning (F = 4.26, P <.05). Comparing baseline scores of functioning on the Medical Outcomes Study Short-Form 36 (MOS SF-36), there was a significant improvement (F = 2.11, P <.05) in general health subscale scores at 1 month after surgery. Subjects' mean overall satisfaction with the results of surgery, with a 0 to 10 scale, was 7.33 +/- 2.84. Again, by using one-way ANOVAs, females had significantly higher mean satisfaction rating than males (F = 4.52, P <.05). Although findings from this pilot study are limited in their generalizability, clinicians need to continue to evaluate opportunities to further reduce variability in clinical practice patterns for optimal patient outcomes. Study findings also indicated that additional interventions are warranted to educate and provide rehabilitation for patients regarding an exercise program and overall behavior modification strategies to reduce risk for atherosclerotic disease.

Frequency dependence of endocytosis in aortic baroreceptor neurons and role of group III mGluRs

Synaptic transmission between baroreceptor afferents and the nucleus tractus solitarius (NTS) is known to exhibit frequency-dependent depression. Reductions in neurotransmitter release and alterations in mechanisms regulating synaptic transmission are hypothesized to be involved in the activity-dependent depression observed in baroreceptor afferent neurons. The present study utilized cultured aortic baroreceptor neurons and the fluorescent dyes FM1-43 and FM2-10 to characterize the process of endocytosis or vesicle retrieval and its dependence on 1) frequency of neuronal activation, 2) metabotropic glutamate receptor (mGluR) activation, and 3) calcium concentrations inside and outside the cell. Endocytosis per spike, measured in fluorescence units after a 10-s stimulus applied at frequencies of 0.5 (53 +/- 4), 1.0 (23 +/- 1), and 10.0 Hz (2.7 +/- 0.2), was significantly depressed at higher frequencies. Blockade of group III mGluRs with (RS)-cyclopropyl-4-phosphonophenylglycine (CPPG) facilitated endocytosis at all frequencies, suggesting that this receptor subtype may be involved in the inhibition of endocytosis. Manipulating the extracellular and intracellular calcium concentrations subsequent to exocytosis had no effect on endocytosis. These results suggest that frequency-dependent depression of endocytosis observed in vitro could contribute to the frequency-dependent depression of baroreceptor afferent neurotransmission and that group III mGluRs inhibit endocytosis.

Behavioural, growth and immune consequences of early weaning in one-week-old large-white piglets

Genetic improvement in sows' prolificity is limited by their milk capacities, which do not allow all piglets to survive or grow normally. This experiment compared the behaviour, growth and immune responses of piglets that were weaned early at 6 days of age (EW) vs. control Large White piglets' (C) suckled by their mothers. Behaviour of 9 litters of 5 to 8 piglets in each group were observed from d5 to d20. All piglets were weighed from birth to d74. Three piglets from each group were slaughtered on d36 for immunological analysis. Until they began to eat dry food, EW piglets walked and vocalised more than C piglets. After that time, when resting, they were less often lying down and more frequently in contact with littermates under the heater. Aggressive behaviour and belly-nosing were more frequent. They displayed a more marked growth check after weaning than did C piglets until 28 days of age. In EW piglets, at 36 days of age, there was a higher density of T- and B-lymphocytes in the gut epithelium and lamina propria, fespectively, in relation to the size of lymphoid follicles of Peyer's patches. The results indicate great behavioural adaptation capacities of very early-weaned piglets, together with earlier maturation of their gut immune system.

Expression of metabotropic glutamate receptors in nodose ganglia and the nucleus of the solitary tract

The purpose of this study was to identify the complement of metabotropic glutamate receptors (mGluRs) expressed in nodose ganglia and the nucleus tractus solitarius (NTS). mRNA from these tissues was isolated and amplified with standard RT-PCR with primers specific for each mGluR subtype. The results of this analysis showed that the NTS expresses all eight mGluR subtypes, whereas nodose ganglia express only group III mGluRs: mGluR4, mGluR6, mGluR7, and mGluR8. Application of the group III-specific mGluR agonist L-(+)-2-amino-4-phosphonobutyric acid (100 microM) reversibly inhibited voltage-gated calcium currents isolated from DiI-labeled aortic baroreceptor neurons and unlabeled nodose neurons. The results of this study suggest that group III mGluRs are the primary mGluR subtype expressed in visceral afferent neurons and that these receptors may be involved in afferent central transmission.

Cellular mechanisms regulating synaptic vesicle exocytosis and endocytosis in aortic baroreceptor neurons

The purpose of this chapter is to review some of the recent progress in the understanding of the cellular and biophysical mechanisms that are involved in the regulation of arterial baroreceptor neurotransmission. Synaptic depression or fatigue following repeated neuronal stimulation has been shown at central baroreceptor synapses in vivo and in vitro. As most of the central neurons have a limited number of vesicles, vesicle retrieval or endocytosis following exocytosis is thought to play a major role in preserving synaptic transmission. We have hypothesized that central baroreceptor terminals may inhibit their own synaptic transmission via feedback activation of presynaptic metabotropic glutamate receptors (mGluRs). We have analyzed the effects of mGluR autoreceptors (group III mGluRs) on voltage-gated calcium channels using standard patch-clamp techniques and on the process of exocytosis and endocytosis in aortic baroreceptor neurons using the quantitative imaging dye FM1-43 and FM2-10. Usng the whole-cell patch-clamp technique, we have found that activation of group III mGluRs with L-AP4 inhibits peak calcium channel current. Furthermore, activation of group III mGluRs with L-AP4 markedly decreases stimulation-induced exocytosis in aortic baroreceptor neurons, as measured with FM1-43, and inhibits synapsin I phosphorylation. These results suggest that activation of group III mGluRs may inhibit synaptic transmission by (1) inhibiting calcium influx, (2) decreasing synaptic vesicle exocytosis, and (3) modulating the mechanisms governing synaptic vesicle recovery and endocytosis. These effects of mGluRs on baroreceptor synaptic vesicles may contribute to the baroreceptor/nucleus tractus solitarius synaptic depression observed in vivo.

Neuroendocrine consequences of very early weaning in swine

An experiment was conducted to investigate the consequences of very early weaning of piglets on neuroendocrine variables and growth. Sixty piglets from eight litters were either weaned on Postnatal Day 6 (early weaning, or EW piglets) or left with their dam until normal weaning at Day 28 (control piglets, or C). At Days 5, 7, 11, 14, and 19, urine was collected between 7:00 and 8:00 a.m. for the measurement of catecholamines, glucocorticoids, and creatinine. Compared with C, EW piglets displayed a transient increase in urinary cortisol on the day following separation from their dam (Day 7) (P<.05). Urinary norepinephrine (NE) was three times lower in EW compared to C piglets from Day 7 until Day 14 (P<.01) but there was no difference between the two groups on Day 19. Urinary epinephrine (EPI) did not differ between C and EW piglets on the day after weaning. Thereafter, EW piglets displayed a three times drop in urinary EPI as compared to C piglets until the end of the period (P<.01). Weaning induced an immediate reduction in food intake and growth rate and at Day 28, the body weight of EW piglets was 1.60 kg lower than that of C piglets (P<.0001). In conclusion, weaning of 6-day-old piglets results in a marked and prolonged suppression of the release of catecholamines. This result likely reflects physiological responses to insufficient energy intake after weaning, as reflected also by changes in thermoregulatory behavior. The transient increase in cortisol excretion in weanlings may be caused by both emotional distress and acute food deprivation.

Activation of metabotropic glutamate receptors inhibits synapsin I phosphorylation in visceral sensory neurons

Activation of glutamate metabotropic receptors (mGluRs) in nodose ganglia neurons has previously been shown to inhibit voltage-gated Ca++ currents and synaptic vesicle exocytosis. The present study describes the effects of mGluRs on depolarization-induced phosphorylation of the synaptic-vesicle-associated protein synapsin I. Depolarization of cultured nodose ganglia neurons with 60 mM KCl resulted in an increase in synapsin I phosphorylation. Application of mGluR agonists 1-aminocyclopentane-1s-3r-dicarboxylic acid (t-ACPD) and L(+)-2-Amino-4-phosphonobutyric acid (L-AP4) either in combination or independently inhibited the depolarization induced phosphorylation of synapsin I. Application of the mGluR antagonist (RS)-alpha-Methyl-4-carboxyphenylglycine (MCPG) blocked t-ACPD-induced inhibition of synapsin phosphorylation but not the effects of L-AP4. In addition, application of either t-ACPD or L-AP4 in the absence of KCl induced depolarization had no effect on resting synapsin I phosphorylation. RT-PCR analysis of mGluR subtypes in these nodose ganglia neurons revealed that these cells only express group III mGluR subtypes 7 and 8. These results suggest that activation of mGluRs modulates depolarization-induced synapsin I phosphorylation via activation of mGluR7 and/or mGluR8 and that this process may be involved in mGluR inhibition of synaptic vesicle exocytosis in visceral sensory neurons of the nodose ganglia.

17-beta-estradiol modulation of area postrema potassium currents

The purpose of this study was to determine the effects of 17-beta-estradiol on area postrema neuronal activity in vivo and on area postrema potassium currents (IK) in vitro. In anesthetized rats, intravenous injection of 17-beta-estradiol (10 ng/kg bw) -inhibited area postrema neuronal activity in 8/8 neurons tested. The averaged firing rate decreased from 2.9 +/- 1.1 to 1.1 +/- 0.3 Hz. The inhibitory effects of 17-beta-estradiol on area postrema neuronal activity were rapid in onset (within 1 min) and long-lasting (>8 min). To study the cellular mechanisms involved in this response, the effects of 17-beta-estradiol were examined in dissociated area postrema neurons. In these cells, 17-beta-estradiol (0.5 nM) increased the averaged peak IK 27 +/- 8%. The time course for the potentiation was observed within approximately 0.5-1 min after the application of 17-beta-estradiol. Full recovery from the potentiation usually occurred within approximately 3-4 min after the washout of 17-beta-estradiol. The biologically inactive 17-alpha-estradiol had no effect on area postrema IK and the 17-beta-estradiol antagonist, ICI 182,780 blocked the effects of 17-beta-estradiol on area postrema IK. Finally, big conductance calcium-activated potassium current (MaxiK(+)) was identified in area postrema neurons (n = 12/12). Blockade of MaxiK(+) with 100 nM iberiotoxin blocked the effects of 17-beta-estradiol on IK. These results suggested 17-beta-estradiol might modulate area postrema neuronal activity by increasing MaxiK(+) current.

Area postrema and sympathetic nervous system effects of vasopressin and angiotensin II

1. Precise control over the cardiovascular system requires the integration of both neural and humoral signals related to blood volume and blood pressure. Humoral signals interact with neural systems, modulating their control over the efferent mechanisms that ultimately determine the level of pressure and volume. 2. Peptide hormones such as angiotensin (Ang)II and arginine vasopressin (AVP) act through circumventricular organs (CVO) to influence cardiovascular regulation. 3. The area postrema (AP), a CVO in the brainstem, mediates at least some of the central actions of these peptides. Vasopressin appears to act in the AP to cause sympathoinhibition and a shift in baroreflex control of the sympathetic nervous system (SNS) to lower pressures. These effects of AVP and the AP appear to be mediated by alpha2-adrenoceptor and glutamatergic mechanisms in the nucleus tractus solitarius. 4. In contrast to AVP AngII has effects in the AP to blunt baroreflex control of heart rate and cause sympathoexcitation. The effects of chronic AngII to increase activity of the SNS may be due to AP-dependent activation of neurons in the rostral ventrolateral medulla.

Assessment of hypothalamic-pituitary-adrenal axis and sympathetic nervous system activity in pregnant sows through the measurement of glucocorticoids and catecholamines in urine

We validated the use of urine to monitor changes in the activity of both the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system (SNS) in swine. Ten pregnant sows were fitted with venous catheters 3 wk after mating. In the early (wk 6), middle (wk 9), and late (wk 14) stages of gestation, blood and urine were collected over 24 h to monitor diurnal changes in plasma cortisol, urinary cortisol, and urinary catecholamines (norepinephrine [NE] and epinephrine [EPI]). Dexamethasone suppression tests (DST) and ovine corticotropin-releasing hormone (CRH) challenge tests were also performed at each stage of gestation. All plasma and urinary values changed markedly around the clock. Diurnal variations of urinary cortisol were comparable to those in plasma, with a late nocturnal peak and a trough occurring in the evening. During the dark period, urinary catecholamines were lower than during the light period. Norepinephrine increased sharply after lights came on and peaked after meal time. Epinephrine began to rise at the end of the dark period and peaked just before meal time. Average plasma cortisol increased with the stage of gestation, due to higher levels during daylight hours. Dexamethasone at 2000 (20 microg/kg i.v.) decreased plasma cortisol at 0830 and nocturnal cortisol excretion. The magnitude of the decrease in plasma ACTH and urinary cortisol after DST was lower in late than in early and midgestation, indicating increased feedback resistance at that stage. The CRH (1 microg/kg i.v.) increased plasma and urinary cortisol. Peak levels occurred 30 min and 2 to 3 h after the injection, respectively. Catecholamines and cortisol in urine produced during the night (2000 to 0800) and the early morning (0400 to 0800 and 0800 to 0900) were highly correlated with their 24-h excretion rate. These results indicate that it is possible to monitor changes in the HPA axis and SNS activity through urinary measurements in pigs.

The impact of HIV infection on Mycobacterium kansasii disease in South African gold miners

The impact of human immunodeficiency virus (HIV) infection on Mycobacterium kansasii disease in miners was investigated with a retrospective study covering a single workforce. M. kansasii, isolated from 43 HIV-positive and 202 HIV-negative miners, was the most common nontuberculous mycobacterial (NTM) species in both HIV groups. CD4 counts were unusually high for M. kansasii disease (mean 490 x 10(6)/L, from 14 HIV-positive men). Treatment outcomes were similar: mortality during treatment was higher in HIV-positive than in HIV-negative men (9% and 2%, respectively), but not significantly so. The majority of a sample of 31 HIV-positive and 92 HIV-negative men had radiological silicosis and/or old tuberculosis scarring prior to M. kansasii disease. A normal premorbid radiograph was more common in HIV-positive men (45% versus 24%; odds ratio [OR], 2.62; 95% confidence interval [95% CI], 1.01 to 6.67). New cavitation was less common (55% versus 78%; OR, 0.34; 95% CI, 0.13 to 0.88) and new hilar adenopathy more common (OR, 5.07; 95% CI, 1.24 to 21.9) in HIV-positive than in HIV-negative men. Miners, who have additional NTM risk factors, develop M. kansasii disease that occurs at an earlier stage of HIV infection and more closely resembles disease in HIV-negative men than has been found for HIV-associated M. kansasii disease in other settings.

Mycobacterium kansasii and M. scrofulaceum isolates from HIV-negative South African gold miners: incidence, clinical significance and radiology

SETTING

A South African gold mining hospital.

OBJECTIVE

To investigate the clinical significance of non-tuberculous mycobacteria (NTM) isolates, and estimate NTM disease incidence in human immunodeficiency virus (HIV) negative miners.

DESIGN

Retrospective case series describing clinical and radiological features associated with NTM sputum isolates from HIV-negative miners between January 1993 and July 1996, and a comparison group with Mycobacterium tuberculosis infection.

RESULTS

Of miners with NTM isolates, 90% had been HIV-tested and 81% were HIV-negative. M. kansasii and M. scrofulaceum accounted for 202 (68%) and 41 (14%) isolates respectively. More than 80% of miners with M. kansasii or M. scrofulaceum were smear positive, and new cavitation was present in 78% and 74% respectively. Treatment failure occurred in 3% of M. kansasii and 12% of M. scrofulaceum patients. A normal pre-morbid radiograph was significantly less common in NTM than M. tuberculosis patients (odds ratio 0.26 and 0.10 for M. kansasii and M. scrofulaceum, respectively). NTM disease incidence, defined as NTM isolate plus new cavitation, was estimated at 66 and 12 per 100000 person-years for M. kansasii and M. scrofulaceum, respectively.

CONCLUSIONS

M. kansasii and M. scrofulaceum disease are common in HIV-negative South African gold miners. Most isolates are associated with new cavitation against a background of silicosis or old TB scarring.

Cardiovascular response to group I metabotropic glutamate receptor activation in NTS

Glutamate is the proposed neurotransmitter of baroreceptor afferents at the level of the nucleus tractus solitarius (NTS). Exogenous glutamate in the NTS activates neurons through ionotropic and metabotropic glutamate receptors (mGluRs). This study tested the hypothesis that group I mGluRs in the NTS produce depressor, bradycardic, and sympathoinhibitory responses. In urethan-anesthetized rats, unilateral 30-nl microinjections of the group I-selective mGluR agonist 3,5-dihydroxyphenylglycine (DHPG) into the NTS decreased mean arterial pressure, heart rate, and lumbar sympathetic nerve activity. The dose of drug that produced 50% of the maximal response (ED50) was 50-100 microM. The response to microinjection of equal concentrations of DHPG or the general mGluR agonist 1-aminocyclopentane-1S,3R-dicarboxylic acid (ACPD) produced similar cardiovascular effects. The cardiovascular response to injection of DHPG or ACPD was abolished by NTS blockade of mGluRs with alpha-methyl-4-carboxyphenylglycine (MCPG). Blockade of ionotropic glutamate receptors with kynurenic acid did not attenuate the response to DHPG or ACPD injection. These data suggest that DHPG and ACPD activate mGluRs in the NTS and do not require ionotropic glutamate receptors to produce their cardiovascular response. In the NTS the group I mGluRs produce responses that are consistent with excitation of neurons involved in reducing sympathetic outflow, heart rate, and arterial pressure.

AMPA receptor activation of area postrema neurons

This study reports on the effects of activation of ionotropic glutamate receptors on area postrema neuron cytosolic calcium concentration ([Ca2+]i). In 140 of 242 area postrema neurons isolated from postnatal rats, application of 100 microM L-glutamate (L-Glu) resulted in a significant increase in [Ca2+]i. The remaining neurons were unaffected. The effects of L-Glu on area postrema [Ca2+]i were dose dependent, with a threshold of response near 1.0 microM and maximal response near 100 microM. To determine if the response of L-Glu in area postrema neurons was due to activation of ionotropic glutamate receptors, the effects of the broad-spectrum ionotropic glutamate receptor antagonist kynurinic acid (Kyn) was determined. Application of 1.0 mM Kyn resulted in a 62.6 +/- 4% inhibition of the L-Glu-evoked response. Application of the selective N-methyl-D-aspartic acid (NMDA) antagonist 2-amino-5-phosphonopentanoic acid had no effect on the response of area postrema neurons to 100 microM L-Glu. In contrast, application of the selective DL-alpha-amino-3-hydroxy-5-methylisoxazole-propionic acid (AMPA)/kainate receptor antagonist 6,7-dinitroquinoxaline (DNQX) effectively blocked the 100 microM L-Glu response. Application of (+/-)-AMPA mimicked the effects observed with L-Glu and was selectively blocked by DNQX. These results suggest that L-Glu activation of area postrema neurons involves activation of AMPA receptors but not NMDA receptors.

Heterogeneity of metabotropic glutamate receptors in autonomic cell groups of the medulla oblongata of the rat

Metabotropic glutamate receptors (mGluRs) in the medulla oblongata have been suggested to be involved in the regulation of autonomic function. The aim of the present study was to examine the localization and expression of four types of mGluRs: mGluRla, mGluR2/3, mGluR5, and mGluR7 in the dorsal and ventral autonomic nuclei of the medulla of the rat. The four mGluR subtypes studied were differentially distributed in distinct subnuclei in the nucleus of the solitary tract (NTS). mGluRla immunoreactivity was identified in cell bodies, dendrites, and axonal processes in the intermediate, dorsal lateral, and interstitial subnuclei of the NTS. No mGluRla immunoreactivity was observed in the commissural or medial NTS subnuclei. Immunoreactivity for mGluR2/3 and mGluR5 as observed in fibers and putative axonal processes in the interstitial, intermediate, and dorsolateral subnuclei of the NTS. In contrast, mGluR7 was expressed primarily in fibers and terminals in the central and commissural NTS subnuclei. Expression of mGluR2/3 was clearly evident in cell bodies, dendrites, and axonal processes within the area postrema. The vagal outflow nuclei were also studied. The dorsal motor nucleus of the vagus (DMN) contained mGluRla cell bodies, dendrites, and axonal fibers and light mGluR2/3 processes. Throughout the rostral-caudal extent of the compact and semicompact formation nucleus ambiguus, mGluRla was found in cell bodies and fibers. Within the caudal and rostral regions of the ventral lateral medulla, mGluRla was observed in cell bodies and fibers. Cell bodies containing mGluRla were found adjacent to cells staining positive for tyrosine hydroxylase (TH) in these regions but were not colocalized with the TH staining. However, mGluRla-expressing neurons in the ventral lateral medulla did appear to receive innervation from TH-containing fibers. These results suggest that the mGluRla-expressing neurons within the ventral lateral medulla are predominantly not catecholaminergic but may be innervated by catecholamine-containing fibers. These data are the first to provide a mapping of the different mGluR subtypes within the medulla and may facilitate predictions regarding the function of L-glutamate neurotransmission in these regions.

Glutamate in the nucleus of the solitary tract activates both ionotropic and metabotropic glutamate receptors

Glutamate is the proposed neurotransmitter of baroreceptor afferents at the level of the nucleus of the solitary tract (NTS). Blockade of ionotropic glutamate receptors with kynurenic acid blocks the arterial baroreflex but, paradoxically, does not abolish the response to exogenous glutamate. This study tested the hypothesis that exogenous glutamate in the NTS activates both ionotropic and metabotropic glutamate receptors (mGluRs). In urethan-anesthetized rats, unilateral microinjections of glutamate into the NTS decreased mean arterial pressure, heart rate, and lumbar sympathetic nerve activity. The cardiovascular response to injection of glutamate was not altered by NTS blockade of mGluRs with alpha-methyl-4-carboxyphenylglycine (MCPG). Blockade of ionotropic glutamate receptors with kynurenic acid attenuated the response to glutamate injection. After combined NTS injection of MCPG and kynurenic acid, the response to glutamate was blocked. These data suggest that exogenous glutamate microinjected into the NTS acts at both ionotropic glutamate receptors and mGluRs. In addition, blockade of both classes of glutamate receptors is required to block the cardiovascular response to microinjection of glutamate in the NTS.

The effects of social support and education on health care costs after three years

OBJECTIVE

To determine whether experimentally developed social support, education about appropriate use of the health care system, and their combination are effective in reducing health care costs for people with osteoarthritis at a 3-year followup assessment.

METHOD

Three hundred sixty-three health maintenance organization members with osteoarthritis were randomly assigned to 1 of 3 intervention groups or to a control group. Two hundred fifty-six participants completed the 3-year assessment. Health status and health care use were assessed upon entering the study, and after 1, 2, and 3 years.

RESULTS

Health care costs in the combined experimental groups were lower than those in the control group by $1,279/participant/year in year 3. There were no significant changes in health status between participants' entry into the study and the year 3 assessment. The 3 interventions had nearly equal effects on health status and health care costs. Implementation costs were least for the social support intervention, but the group that combined education and social support had less attrition and greater persistence.

CONCLUSION

Interventions that target appropriate use of the health care system can be highly cost-effective without adversely affecting health status.

Measurement of synaptic vesicle exocytosis in aortic baroreceptor neurons

The purpose of this study was to evaluate the use of the fluorescent membrane label FM1-43 as a measure of synaptic terminal exocytosis during stimulation of labeled aortic baroreceptor and unlabeled nodose ganglia neurons. Activation of the nerve terminals with electrical stimulation or depolarization with 90 mM KCl in the presence of 2.0 microM FM1-43 resulted in bright, punctate staining of synaptic boutons. Additional depolarization in the absence of dye resulted in destaining with a time course that was consistent and repeatable in multiple boutons within a given terminal. Destaining was dependent on calcium influx and was blocked by bath application of 100 microM CdCl2. Whole cell patch-clamp studies have reported that depolarization-induced calcium influx in aortic baroreceptor cell bodies is predominantly caused by the activation of omega-conotoxin GVIA (omega-CgTx)-sensitive N-type calcium channels. In addition, these N-type channels have been shown to be inhibited by activation of metabotropic glutamate receptors. In the present study, exocytosis in aortic baroreceptor terminals was not affected by bath application of 5 microM nifedipine and only partially inhibited by bath application of 2.0 microM omega-CgTx. However, depolarization-induced exocytosis was significantly inhibited by bath application of 200 microM L-AP4, a type III metabotropic glutamate receptor agonist. Results from this study suggest that 1) FM1-43 can be used to measure synaptic vesicle exocytosis in baroreceptor neurons; 2) the N-type calcium channel may not be involved in the initial phase of vesicle exocytosis; and 3) activation of L-AP4-sensitive metabotropic glutamate receptors inhibits 90 mM KCl-induced vesicle release.

[Radiotherapy of stage T1-T2 M0 prostatic adenocarcinoma. Analysis of the carcinologic results of a multicenter study of 610 patients. Groupe Radiothérapie de la Commission de Coopération Médicale Intercentres (CCMI)]

PURPOSE

Retrospective analysis of the results of radiotherapy in localized prostatic adenocarcinoma. Complications were excluded.

PATIENTS AND METHODS

Six-hundred-and-ten T1-T2 adenocarcinomas of the prostate were treated with continuous courses of external beam radiation therapy in 19 participating Institutes between January 1983 and January 1988. The mean follow-up was 10.4 years; the mean age of patients at the beginning of radiotherapy was 68.5 years.

RESULTS

A 10-year, local control had been achieved in 86% of T1-T2 (81.4% for T2). The 5- and 10-year metastatic relapse rates were 25.3% and 30% (29% and 38.1% for T2), respectively. At 10 years, 62.4% of T1-T2 were recurrence-free; overall survival rate was 45.8% and cause-specific survival rate was 70.5%; 29.9% of T1-T2 patients were alive and disease-free. T category (TNM), pathologic grade, pelvic lymph node status, local tumor control, and obstructive ureteral symptoms were correlated with survival. The influence of pelvic nodes radiation, dose, overall treatment time, previous endocrine treatment, and transuretral resection was not significant for disease-free survival (alive and disease-free) and other endpoints.

CONCLUSION

There was no difference between the French series (1975-1982 and 1983-1988). The results of the literature are comparable to ours. As far as prognostic factors are concerned, this report provides evidence that the explainable variables which influence survival depend on the tumor and patient status.

Cyclosporine A modulation of Ca++ activated K+ channels in cardiac sensory afferent neurons

Whole-cell and single channel recordings were used to characterize the effects of the immunosuppressant cyclosporine A (CsA) on cardiac sensory neurons (CSN) of the nodose ganglia. Application of 10 nM CsA resulted in a 29.1% decrease in CSN input resistance and an average -8+/-3 mV hyperpolarization of membrane potential. Application of 10 nM CsA had no effect on evoked Ca++ currents but increased evoked K+ currents by 158.9+/-24%. Application of 10 nM CsA significantly increased the open probability of KCa channels by 183+/-9%. These results suggest that application of CsA results in the activation of KCa channels in cardiac sensory neurons and this effect may contribute to the cellular mechanisms underlying CsA modulation of vagal afferent neurons.

Urinary excretion of catecholamines, cortisol and their metabolites in Meishan and large white sows: validation as a non-invasive and integrative assessment of adrenocortical and sympathoadrenal axis activity

Urinary free corticoids (cortisol and cortisone), catecholamines (norepinephrine or NE, epinephrine or E, dopamine or DA, and their O-methoxylated metabolites) as well as creatinine (Cr) were analysed in 42 spontaneously voided urine samples from Large White (LW, n = 20), Meishan (MS, n = 6), and LW x MS (F1, n = 16) lactating sows. The cortisol concentration in the urine of MS (28.1 pg/micrograms Cr) was five-fold greater than that of LW sows (6.2 pg/micrograms Cr, P < 10(-4)). F1 were intermediate (12.0 pg/micrograms Cr). Mean cortisone concentration was also larger in MS (13.5 pg/micrograms Cr) compared to LW (7.1 pg/micrograms Cr, P < 0.01). Although the differences were less pronounced, the concentrations of the catecholamines were also greater in MS than in LW sows (norepinephrine: 25.4 versus 5.9 pg/micrograms Cr, epinephrine: 8.7 versus 2.8 pg/micrograms Cr and dopamine: 59.2 versus 17.8 pg/micrograms Cr, P < 10(-4)). These results confirmed the hypercortisolism state of MS pigs previously shown by plasma cortisol assay and supported the hypothesis that the sympathetic nervous system is hyperactive in this breed. These urinary investigations may offer possible applications for the assessment of chronic stress.

Determination of catecholamines and methoxycatecholamines excretion patterns in pig and rat urine by ion-exchange liquid chromatography with electrochemical detection

A simplified liquid chromatographic method for the simultaneous determination of free or total catecholamines and methoxycatecholamines in rat and pig urine is presented. The extraction procedure involves a two-stage batch extraction, with successive adsorption on cation- (catecholamine elution) and anion-exchange columns (methoxycatecholamine elution). The column eluates are successively monitored by reversed-phase high-performance liquid chromatography (HPLC) with electrochemical detection. The proportion of conjugates for each compound was assessed in both species, through the comparison of concentrations with or without hydrolysis pretreatment. Conjugates were found to account for a small fraction of total catecholamines and methoxycatecholamines excretion (0 to 35%). The free fraction of each compound was highly correlated with the total amount. Furthermore, the hydrolysis procedure leads to partial degradation of metanephrine (25%) and to the production of compounds giving artefactual peaks. Thus, we do not recommend hydrolysis of rat and pig urines for catecholamine and methoxycatecholamine determination.

Improved determination of urinary cortisol and cortisone, or corticosterone and 11-dehydrocorticosterone by high-performance liquid chromatography with ultraviolet absorbance detection

A sensitive assay was developed for the determination of low levels of free (unconjugated) glucocorticoids in human, swine (cortisol and cortisone) and rat urine (corticosterone and 11-dehydrocorticosterone), using solid-phase extraction and HPLC with UV absorbance detection (254 nm). Precise quantitation is allowed by the use of internal standards (dexamethasone for swine urine and Reichstein's substance S for rat urine). This simple method allows the use of small urine samples (less than 2 ml), and is suitable for a wide range of applications in human and animal clinical and physiological studies.