Poor predictive value of lower gastrointestinal alarm features in the diagnosis of colorectal cancer in 1981 patients in secondary care

BACKGROUND

Clinicians are advised to refer patients with lower gastrointestinal (GI) alarm features for urgent colonoscopy to exclude colorectal cancer (CRC). However, the utility of alarm features is debated.

AIM

To assess whether performance of alarm features is improved by using a symptom frequency threshold to trigger referral, or by combining them into composite variables, including minimum age thresholds, as recommended by the National Institute for Health and Care Excellence (NICE).

METHODS

We collected data prospectively from 1981 consecutive adults with lower GI symptoms. Assessors were blinded to symptom status. The reference standard to define CRC was histopathological confirmation of adenocarcinoma in biopsy specimens from a malignant-looking colorectal lesion. Controls were patients without CRC. Sensitivity, specificity, positive predictive values (PPVs) and negative predictive values were calculated for individual alarm features, as well as combinations of these.

RESULTS

In identifying 47 (2.4%) patients with CRC, individual alarm features had sensitivities ranging from 11.1% (family history of CRC) to 66.0% (loose stools), and specificities from 30.5% (loose stools) to 75.6% (family history of CRC). Using higher symptom frequency thresholds improved specificity, but to the detriment of sensitivity. NICE referral criteria also had higher specificities and lower sensitivity, with PPVs above 4.8%. More than 80% of those with CRC met at least one of the NICE referral criteria.

CONCLUSIONS

Using higher symptom frequency thresholds for alarm features improved specificity, but sensitivity was low. NICE referral criteria had PPVs above 4.8%, but sensitivities ranged from 2.2% to 32.6%, meaning many cancers would be missed.

No increase in prevalence of somatization in functional vs organic dyspepsia: a cross-sectional survey

BACKGROUND

Psychological factors are associated with functional gastrointestinal (GI) disorders. Literature suggests that somatization is associated with functional dyspepsia (FD). However, the relationship between organic dyspepsia (OD), FD, and FD subtypes and somatization is poorly described. We aimed to examine this issue in a cross-sectional study of secondary care patients.

METHODS

Demographic and GI symptom data were collected from 4224 adult patients via the Rome III questionnaire. Somatization data were collected using the patient health questionnaire-12. Mean somatization score and number of somatic symptoms were compared between patients with organic and FD, and between FD subtypes using analysis of variance. The same comparison was undertaken for the proportion of patients reporting individual somatic symptoms.

KEY RESULTS

Exactly, 783 patients met criteria for dyspepsia, of whom 231 (29.5%) had organic disease following upper GI endoscopy. Mean somatization scores and number of somatic symptoms were no higher in functional vs OD (p = 0.23; p = 0.19). In addition, while the prevalence of somatization in FD was relatively high, there was no difference in severity of somatization in FD subgroups.

CONCLUSIONS & INFERENCES

Somatization is associated with functional and OD to the same degree. Overall severity of somatization did not appear to vary according to FD subtype.

Irritable bowel syndrome is significantly associated with somatisation in 840 patients, which may drive bloating

BACKGROUND

Psychological factors may influence persistence and perceived severity of symptoms in irritable bowel syndrome (IBS). Literature suggests that somatisation is associated with IBS. However, the relationship between IBS subtype, symptoms of IBS and somatisation is unclear.

AIM

To examine this issue in a large cohort of secondary care patients.

METHODS

Demographic and gastrointestinal (GI) symptom data were collected from 4224 adult patients via the Rome III questionnaire. Somatisation data were collected using the patient health questionnaire-12. Mean somatisation score and number of somatic symptoms were compared between IBS patients and controls with minimal GI symptoms, and between IBS subtypes using analysis of variance. Effect of level of somatisation on symptom frequency was compared according to IBS subtype using a χ(2) test.

RESULTS

840 patients met Rome III criteria for IBS, controls were 2137 patients with GI symptoms without IBS. Mean somatisation scores and number of somatic symptoms were higher in IBS vs. controls (P < 0.001), and in mixed stool pattern IBS (IBS-M), vs. IBS with constipation (IBS-C) or diarrhoea (IBS-D) (P < 0.001). High levels of somatisation were more prevalent in IBS-M (31.7%) vs. IBS-C (22.5%) or IBS-D (20.8%) (P = 0.003). For all IBS subtypes, high levels of somatisation were associated with a greater frequency of bloating or abdominal distension prior to logistic regression.

CONCLUSIONS

IBS is strongly associated with higher levels of somatisation, particularly IBS-M. Bloating may be associated with higher levels of somatisation, perhaps explaining why it can be difficult to treat.

Design of ruthenium/iron oxide nanoparticle mixtures for hydrogenation of nitrobenzene

Magnetically recoverable catalysts containing Ru/RuO₂ and iron oxide nanoparticles show remarkable activity and selectivity in nitrobenzene-to-aniline hydrogenation.

Characteristics of functional bowel disorder patients: a cross-sectional survey using the Rome III criteria

BACKGROUND

There is some evidence that, despite attempts to classify them separately, functional bowel disorders are not distinct entities and that such divisions are artificial.

AIM

To examine this issue in a large cohort of secondary care patients.

METHODS

Consecutive, unselected adults with gastrointestinal (GI) symptoms attending out-patient clinics at two hospitals in Hamilton, Ontario were recruited. Demographic data, symptoms and presence of anxiety, depression or somatisation were collected prospectively. We used validated questionnaires, including the Rome III questionnaire, with patients categorised as having irritable bowel syndrome (IBS), functional diarrhoea or chronic idiopathic constipation (CIC). We compared data between these disorders, and measured degree of overlap between them by suspending their mutual exclusivity.

RESULTS

Of 3656 patients providing complete lower GI symptom data, 1551 (42.4%) met criteria for a functional bowel disorder. Diarrhoea-predominant IBS (IBS-D) patients were younger, and more were female, met criteria for anxiety, and reported somatisation-type behaviour, compared with functional diarrhoea. Only loose, mushy or watery stools were more common in functional diarrhoea. When mutual exclusivity was suspended, overlap occurred in 27.6%. Constipation-predominant IBS (IBS-C) patients were younger, and more were female, had never married, reported anxiety type symptoms and exhibited somatisation-type behaviour. One in five CIC patients reported abdominal pain or discomfort. All constipation symptoms were more common in IBS-C. When the mutual exclusivity was suspended, overlap occurred in 18.1%.

CONCLUSIONS

There were significant differences in demographics between individuals with functional bowel disorders. Despite this, the Rome III classification system falls short of describing unique entities.

Work stress and physical assault of nursing aides in rural nursing homes with and without dementia special care units

PURPOSE

This study compared nursing aides (NAs) employed in rural nursing homes with and without dementia special care units (SCUs) on (1) exposure to and distress from disruptive behaviours exhibited by residents, (2) job strain and (3) physical assault.

DESIGN AND METHODS

The data were drawn from a larger study conducted in Saskatchewan, Canada, in which all rural nursing homes of < or = 100 beds that had an SCU were matched to same-sized rural facilities with no SCU. Nursing aides (n = 355) completed a mailed survey questionnaire.

RESULTS

Nursing aides employed in nursing homes with an SCU reported significantly less frequent exposure to disruptive behaviours (including aggressive and aversive behaviours) than NAs in non-SCU facilities, less distress when these behaviours were directed toward them, less exposure to aggressive behaviour during caregiving, lower job demands and lower job strain. There was a trend toward increased risk of being assaulted in the last year associated with being in a non-SCU facility. Having a permanent position, increased job strain, and feeling inadequately prepared for dementia care were significantly associated with higher risk of being assaulted. In the SCU facilities, NAs who worked more time on the SCU reported more assaults but less distress from disruptive behaviour, lower psychological job demands, lower job strain and greater work autonomy.

IMPLICATIONS

Providing more dementia care training and reducing job demands and job strain may help to reduce work-related stress and physical assault of nursing aides employed in nursing homes.

Evaluating rural nursing home environments: dementia special care units versus integrated facilities

Although one in four seniors currently lives in a rural area, little is known about the capacity of rural nursing homes to provide specialized dementia services. The physical and social environments are increasingly recognized as important factors in the quality of life and functional ability of persons with dementia. This study compared eight rural nursing homes (those located in centres with populations < or =15,000) that had created dementia Special Care Units (SCUs) to eight same-sized rural nursing homes that did not have SCUs. Outcomes were assessed in relation to residents, staff, family members, and the environment. In this paper we describe the overall study design and findings from the environmental assessment. Analysis of variance (ANOVA) was used to compare the SCU versus non-SCU environments on the nine dimensions of the Physical Environmental Assessment Protocol (PEAP), which was used to assess the physical environment. The SCUs were more supportive on six dimensions: maximizing awareness and orientation, maximizing safety and security, regulation of stimulation, quality of stimulation, opportunities for personal control, and continuity of the self. Analysis of variance was also used to compare the groups on the six subscales of the Nursing Unit Rating Scale (NURS), which assesses the social environment of dementia care settings. The SCUs were more supportive on the Separation and Stimulation subscales, indicating that SCUs had greater separation of residents with dementia from other residents for activities of daily living and programming, and better control of non-meaningful stimulation.

Light therapy for managing sleep, behaviour, and mood disturbances in dementia

BACKGROUND

Rest-activity and sleep-wake cycles are controlled by the endogenous circadian rhythm generated by the suprachiasmatic nuclei (SCN) of the hypothalamus. Degenerative changes in the SCN appear to be a biological basis for circadian disturbances in people with dementia, and might be reversed by stimulation of the SCN by light.

OBJECTIVES

The review assesses the efficacy of bright light therapy (BLT) in managing sleep, behaviour, mood, and cognitive disturbances associated with dementia.

SEARCH STRATEGY

The trials were identified from a search of the Specialized Register of the Cochrane Dementia and Cognitive Improvement Group on 27 January 2004 using the terms "bright light*", "light box*", "light visor*", "dawn-dusk*", phototherapy (MESH), phototherapy, "photo therapy", "light therapy" "light treatment", light*.

SELECTION CRITERIA

All relevant, randomized controlled trials in which BLT, at any intensity and duration, was compared with a control group for the effect on managing sleep, behavioural, mood, and cognitive disturbances (as well as changes in institutionalization rates and cost of care) on people with dementia of any degree of severity.

DATA COLLECTION AND ANALYSIS

Three reviewers independently assessed the retrieved articles for relevance, methodological quality, and extracted data from the selected studies. The statistically significant differences in changes in outcomes from baseline to end of treatment and from baseline to follow-up between the light therapy and control groups were examined. Each study was summarized using a measure of effect (e.g. mean difference). Owing to lack of homogeneity between studies, their results were not combined.

MAIN RESULTS

Five studies met the inclusion criteria. However, only three were included in the analyses because of inappropriate analyses reported or inability to retrieve the required data from the investigators. This review revealed no adequate evidence of the effectiveness of BLT in managing sleep, behaviour, and mood disturbances associated with dementia.

REVIEWERS' CONCLUSIONS

There is insufficient evidence to assess the value of BLT for people with dementia. The available studies are of poor quality and further research is required.

Validating two methods for monitoring population size of the European rabbit (Oryctolagus cuniculus)

Two methods commonly used to monitor population sizes of the wild European rabbit (Oryctolagus cuniculus) are spotlight transect counts and active burrow-entrance counts. The accuracy and precision of these techniques were assessed by comparing monitoring data with population estimates derived from intensive observation of a tagged rabbit population near Melbourne, Australia. Both monitoring methods proved capable of yielding population indices linearly related to population density and robust to seasonal changes in population dynamics. The influence of environmental and temporal variables on rabbit emergence, and hence on spotlight transect data, was also investigated. By using data collected over a wide range of weather conditions, 55% of the variation in evening emergence behaviour of rabbits could be predicted by environmental and temporal factors, with solar time, precipitation, air temperature and wind speed accounting for most of this. However, the precision of spotlight transect count data, which are routinely collected at a fixed time of night under mild weather conditions, was not improved by attempting to correct for the effects of weather and time on emergence; continuing to conduct counts under such conditions was supported as a reliable practice.

Duration and specificity of humoral immune responses in mice vaccinated with the Alzheimer's disease-associated beta-amyloid 1-42 peptide

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by overproduction of beta-amyloid (Abeta), which is formed from amyloid precursor protein (APP), with the subsequent pathologic deposition of Abeta in regions of the brain important for memory and cognition. Recently, vaccination of murine models of AD that exhibit Abeta deposition has halted or delayed the usual progression of the pathology of AD. Our group has demonstrated that vaccination of a doubly transgenic mouse model (expressing mutant APP and presenilin-1) with the Abeta 1-42 peptide protects these mice from the memory deficits they would ordinarily develop. This report further characterizes the Abeta 1-42 peptide vaccine in mice. Anti-Abeta response time course analysis indicated that at least three vaccinations (each 100 microg) were necessary to elicit a significant anti-Abeta titer. Subsequent vaccinations resulted in half-maximal antibody titers of at least 10,000, and these titers were maintained for at least 5 months after the final boost. Peptide binding competition studies indicated that the highest humoral responses are generated against the N terminus of the Abeta peptide. Also, measurement of specific murine Ig isotypes in Abeta-vaccinated mice demonstrated a predominant IgG(1) and IgG(2b) response, suggesting a type 2 (Th2) T-helper cell immune response, which drives humoral immunity. Finally, lymphocyte proliferation assay experiments using Abeta peptides and splenocytes from vaccinated mice demonstrated that the vaccine specifically stimulates T-cell epitopes present within the Abeta peptide.

Structures of bacterial flagellar motors from two FliF-FliG gene fusion mutants

Flagella purified from Salmonella enterica serovar Typhimurium contain FliG, FliM, and FliN, cytoplasmic proteins that are important in torque generation and switching, and FliF, a transmembrane structural protein. The motor portion of the flagellum (the basal body complex) has a cytoplasmic C ring and a transmembrane M ring. Incubation of purified basal bodies at pH 4.5 removed FliM and FliN but not FliG or FliF. These basal bodies lacked C rings but had intact M rings, suggesting that FliM and FliN are part of the C ring but not a detectable part of the M ring. Incubation of basal bodies at pH 2.5 removed FliG, FliM, and FliN but not FliF. These basal bodies lacked the C ring, and the cytoplasmic face of the M ring was altered, suggesting that FliG makes up at least part of the cytoplasmic face of the M ring. Further insights into FliG were obtained from cells expressing a fusion protein of FliF and FliG. Flagella from these mutants still rotated but cells were not chemotactic. One mutant is a full-length fusion of FliF and FliG; the second mutant has a deletion lacking the last 56 residues of FliF and the first 94 residues of FliG. In the former, C rings appeared complete, but a portion of the M ring was shifted to higher radius. The C-ring-M-ring interaction appeared to be altered. In basal bodies with the fusion-deletion protein, the C ring was smaller in diameter, and one of its domains occupied space vacated by missing portions of FliF and FliG.

Pathology and pathophysiology of drug-induced arterial injury in laboratory animals and its implications on the evaluation of novel chemical entities for human clinical trials

In toxicology studies, drug-induced arterial injury in laboratory animals continues to be a pressing issue of concern, particularly to those engaged in the discovery and development of novel therapies intended for human use. The concern is justifiably magnified because, currently, there is no unequivocal biochemical marker of arterial injury and/or toxicity in animals or man. Therefore, in laboratory animals used for toxicology studies a precise description of arterial lesions in terms of location, distribution and morphologic character is necessary so that a correlation can be drawn between structural damage and derangement of specific cardiovascular functions. The critical nature of the latter cannot be over-emphasized because this will provide a basis for understanding the mechanism of toxicity, the pathogenesis of the lesion and assessment of human risk. However, in the decision making process, utilization of pattern recognition must be supported by rigorous scientific investigations aimed at establishing a link, where possible, between the deranged cardiovascular function and alterations in cellular, biochemical and molecular events. Conceivably, engagement of the molecular pharmacology target initiates a series of interactive cascades among cellular and non-cellular arterial components that culminate in organ damage. Therefore, any investigative mechanistic studies aimed at understanding the initiation and development of arterial lesions in laboratory animals must make a conscientious attempt to identify and characterize the molecular target of toxicity.

Evidence of an orexigenic role for cocaine- and amphetamine-regulated transcript after administration into discrete hypothalamic nuclei

Cocaine- and amphetamine-regulated transcript is expressed in hypothalamic regions involved in the central control of food intake. Previous data have implicated cocaine- and amphetamine-regulated transcript as an anorectic peptide. We studied the effect of the active fragment of cocaine- and amphetamine-regulated transcript, cocaine- and amphetamine-regulated transcript-(55-102), on feeding when injected into discrete nuclei of the hypothalamus. Cocaine- and amphetamine-regulated transcript-(55-102) (0.04 nmol) elicited a delayed, but significant, increase in feeding in 24-h fasted rats after injection into the ventromedial nucleus (1-2 h, 261 +/- 60% of control; P < 0.05) and arcuate nucleus (1-2 h, 225 +/- 38% of control; P < 0.05) of the hypothalamus. Administration of a higher dose of cocaine- and amphetamine-regulated transcript-(55-102) (0.2 nmol) elicited a significant increase in feeding after injection into the ventromedial nucleus (1-2 h, 1253 +/- 179% of control; P < 0.001), arcuate nucleus (1-2 h, 265 +/- 43% of control; P < 0.05), paraventricular nucleus (2-4 h food intake, 186 +/- 29% of control; P < 0.05), lateral hypothalamic area (2-4 h, 280 +/- 34% of control; P < 0.001), anterior hypothalamic area (2-4 h, 252 +/- 42% of control; P < 0.01), dorsomedial nucleus (2-4 h, 368 +/- 29% of control;P < 0.001) and supraoptic nucleus (2-4 h, 212 +/- 34% of control; P < 0.05) of the hypothalamus. Administration of cocaine- and amphetamine-regulated transcript-(55-102) into the third ventricle of the hypothalamus resulted in an inhibition in feeding [0-4 h (0.4 nmol), 33 +/- 13% control; P < 0.001], but was associated with marked abnormalities in behavior, which may have interfered with feeding. These behavioral abnormalities were not observed after the administration of cocaine- and amphetamine-regulated transcript-(55-102) directly into the arcuate nucleus. These data suggest that cocaine- and amphetamine-regulated transcript may play an orexigenic role in the hypothalamic feeding circuitry.

The central effects of orexin-A in the hypothalamic-pituitary-adrenal axis in vivo and in vitro in male rats

Orexin-A is synthesized in the posterolateral hypothalamus and immunoreactive fibres project to many central nervous system structures, including the paraventricular nucleus, which is rich in corticotropin releasing factor (CRF) neurones and neuropeptide Y (NPY) innervation. We investigated the central effects of orexin-A on the hypothalamic-pituitary-adrenal (HPA) axis by measuring plasma concentrations of corticosterone and adrenocorticotropic hormone (ACTH) in vivo. We explored the potential neuropeptide pathways involved by investigating the effects of orexin-A on CRF, NPY, arginine vasopressin (AVP) and noradrenaline release from hypothalamic explants in vitro. Intracerebroventricular (i.c.v.) injection of orexin-A (3 nmol) in male rats stimulated increases in plasma concentrations of corticosterone between 10 and 40 min after injection, and of plasma ACTH at 20 and 90 min after injection. Orexin-A significantly stimulated CRF and NPY release from hypothalamic explants in vitro. Orexin-A did not stimulate CRF release in the presence of the selective NPY Y1 receptor antagonist, BIBP3226. BIBP3226 alone did not alter CRF release from hypothalamic explants. Orexin-A had no effect in vitro on the release of other neuropeptides, AVP and noradrenaline, involved in the central regulation of the HPA axis. These results suggest that orexin-A is involved in activation of the HPA axis, and that these effects could be mediated via the release of NPY.

Actions of cocaine- and amphetamine-regulated transcript (CART) peptide on regulation of appetite and hypothalamo-pituitary axes in vitro and in vivo in male rats

Cocaine- and amphetamine-regulated transcript (CART) and CART peptide are abundant in hypothalamic nuclei controlling anterior pituitary function. Intracerebroventricular (ICV) injection of CART peptide results in neuronal activation in the paraventricular nucleus (PVN), rich in corticotrophin-releasing factor (CRH) and thyrotrophin-releasing factor (TRH) immunoreactive neurons. The aims of this study were three-fold. Firstly, to examine the effects of CART peptide on hypothalamic releasing factors in vitro, secondly, to examine the effect of ICV injection of CART peptide on plasma pituitary hormones and finally to examine the effect of PVN injection of CART peptide on food intake and circulating pituitary hormones. CART(55-102) (100 nM) peptide significantly stimulated the release of CRH, TRH and neuropeptide Y from hypothalamic explants but significantly reduced alpha melanocyte stimulating hormone release in vitro. Following ICV injection of 0.2 nmol CART(55-102), a dose which significantly reduces food intake, plasma prolactin (PRL), growth hormone (GH) and adrenocorticotrophin hormone (ACTH) and corticosterone increased significantly. Following PVN injection of CART(55-102), food intake was significantly reduced only at 0.2 and 0.6 nmol. However, PVN injection of 0.02 nmol CART(55-102) produced a significant increase in plasma ACTH. ICV injection of CART peptide significantly reduces food intake. Unlike many anorexigenic peptides, there is no increased sensitivity to PVN injection of CART(55-102). In contrast, both ICV and PVN injection of CART(55-102) significantly increased plasma ACTH and release of hypothalamic CRH is significantly increased by CART peptide in vitro. This suggests that CART peptide may play a role in the control of pituitary function and in particular the hypothalamo-pituitary adrenal axis.

Effects of chronic central nervous system administration of agouti-related protein in pair-fed animals

The melanocortin receptor (MC3-R and MC4-R) antagonist, agouti-related protein (AGRP), is a potent stimulant of food intake. We examined the effect of chronic intracerebroventricular (ICV) AGRP treatment on energy metabolism and pituitary function in ad libitum fed rats and rats administered AGRP and then pair-fed to a saline control group. Chronic ICV AGRP (83-132) administration (1 nmol/day for 7 days) significantly increased food intake and body weight in ad libitum fed animals compared with saline-treated controls (body weight on day 7: 272 +/- 6 [saline] vs. 319 +/- 8 g [AGRP ad libitum fed]; P < 0.001). A significant increase in the epididymal fat pad weight, interscapular brown adipose tissue (BAT) weight, and plasma leptin was also observed in the ad libitum fed group. In the AGRP pair-fed group, a significant increase in the epididymal fat pad weight, BAT weight, and plasma leptin was again observed, suggesting that AGRP caused metabolic changes independent of increased food intake. BAT uncoupling protein 1 (UCP-1) content was significantly decreased compared with saline controls in both the AGRP ad libitum fed (21 +/- 8% of saline control; P < 0.01) and AGRP pair-fed groups (24 +/- 7% of saline control; P < 0.01). Plasma thyroid-stimulating hormone (TSH) was significantly suppressed compared with saline controls in both the AGRP ad libitum fed and AGRP pair-fed groups (3.5 +/- 0.3 [saline] vs. 2.7 +/- 0.4 [AGRP ad libitum fed] vs. 2.1 +/- 0.2 ng/ml [AGRP pair-fed]; P < 0.01). This study demonstrates that independent of its orexigenic effects, chronic AGRP treatment decreased BAT UCP-1, suppressed plasma TSH, and increased fat mass and plasma leptin, suggesting that it may play a role in energy expenditure.

The bacterial flagellar cap as the rotary promoter of flagellin self-assembly

The growth of the bacterial flagellar filament occurs at its distal end by self-assembly of flagellin transported from the cytoplasm through the narrow central channel. The cap at the growing end is essential for its growth, remaining stably attached while permitting the flagellin insertion. In order to understand the assembly mechanism, we used electron microscopy to study the structures of the cap-filament complex and isolated cap dimer. Five leg-like anchor domains of the pentameric cap flexibly adjusted their conformations to keep just one flagellin binding site open, indicating a cap rotation mechanism to promote the flagellin self-assembly. This represents one of the most dynamic movements in protein structures.

Central administration of orexin A suppresses basal and domperidone stimulated plasma prolactin

Orexin immunoreactive fibres are abundant in the hypothalamus suggesting a neuroendocrine regulatory role. Intracerebroventricular (ICV) administration of orexin A suppressed plasma prolactin in male rats by 71% at 20 min post-injection and 83% at 90 min post-injection (P < 0.005 vs saline at both time points). To investigate whether this effect was through the tuberoinfundibular dopaminergic (TIDA) system, a supra-maximal dose of domperidone, a dopamine receptor antagonist, was injected intraperitoneally (i.p.) prior to ICV injection of orexin A. ICV orexin A significantly suppressed domperidone (9 mg/kg)-stimulated plasma prolactin levels, by up to 40% (i.p. domperidone + ICV orexin A 3 nmol 34.5 +/- 7.4 ng/ml and i.p. domperidone + ICV orexin A 20 nmol 43.5 +/- 4.3 ng/ml, both P < 0.005 vs i.p. domperidone + ICV saline 57.9 +/- 2.7 ng/ml). Orexin A, 100 nM, significantly stimulated release of neurotensin, vasoactive intestinal polypeptide, somatostatin, corticotropin releasing factor and luteinizing hormone releasing hormone, but had no effect on release of dopamine, thyrotropin releasing hormone (TRH), vasopressin or melanin-concentrating hormone from hypothalamic explants in vitro. Orexin A did not alter basal or TRH stimulated prolactin release in dispersed pituitary cells harvested from male rats. The data suggest that ICV administration of orexin A suppresses plasma prolactin in part through a pathway independent of the dopaminergic system.

The novel hypothalamic peptide ghrelin stimulates food intake and growth hormone secretion

Ghrelin, a novel 28 amino acid peptide found in hypothalamus and stomach, was recently identified as the endogenous ligand for the growth hormone secretagogue receptor (GHS-R). We have now found that both intracerebroventricular (i.c.v.) and intraperitoneal (i.p.) administration of ghrelin in freely feeding rats stimulated food intake. The onset of increased feeding was rapid and after i.c.v. administration was sustained for 24 hours. Following i.c.v. administration of 3 nmol ghrelin, the duration and magnitude of the feeding stimulation was similar to that following 5 nmol neuropeptide Y (NPY). Plasma growth hormone (GH) concentration increased following both i.c.v. and i.p. administration of ghrelin. Release of adrenocorticotrophic hormone (ACTH) was stimulated and thyroid stimulating hormone (TSH) inhibited following i.c.v. administration of ghrelin. These data suggest a possible role for the newly identified endogenous hypothalamic peptide, ghrelin, in stimulation of feeding and growth hormone secretion.

The structure of ribosome-channel complexes engaged in protein translocation

Cotranslational translocation of proteins requires ribosome binding to the Sec61p channel at the endoplasmic reticulum (ER) membrane. We have used electron cryomicroscopy to determine the structures of ribosome-channel complexes in the absence or presence of translocating polypeptide chains. Surprisingly, the structures are similar and contain 3-4 connections between the ribosome and channel that leave a lateral opening into the cytosol. Therefore, the ribosome-channel junction may allow the direct transfer of polypeptides into the channel and provide a path for the egress of some nascent chains into the cytosol. Moreover, complexes solubilized from mammalian ER membranes contain an additional membrane protein that has a large, lumenal protrusion and is intercalated into the wall of the Sec61p channel. Thus, the native channel contains a component that is not essential for translocation.

A strategy for primary high throughput cytotoxicity screening in pharmaceutical toxicology

PURPOSE

Recent advances in combinatorial chemistry and high throughput screens for pharmacologic activity have created an increasing demand for in vitro high throughput screens for toxicological evaluation in the early phases of drug discovery.

METHODS

To develop a strategy for such a screen, we have conducted a data mining study of the National Cancer Institute's Developmental Therapeutics Program (DTP) cytotoxicity database.

RESULTS

Using hierarchical cluster analysis, we confirmed that the different tissues of origin and individual cell lines showed differential sensitivity to compounds in the DTP Standard Agents database. Surprisingly, however, approaching the data globally, linear regression analysis showed that the differences were relatively minor. Comparison with the literature on acute toxicity in mice showed that the predictive power of growth inhibition was marginally superior to that of cell death.

CONCLUSIONS

This datamining study suggests that in designing a strategy for high throughput cytotoxicity screening: a single cell line, the choice of which may not be critical, can be used as a primary screen; a single end point may be an adequate measure and a cut off value for 50% growth inhibition between 10(-6) and 10(-8) M may be a reasonable starting point for accepting a cytotoxic compound for scale up and further study.

A comparison of the yeast and rabbit 80 S ribosome reveals the topology of the nascent chain exit tunnel, inter-subunit bridges and mammalian rRNA expansion segments

Protein synthesis in eukaryotes is mediated by both cytoplasmic and membrane-bound ribosomes. During the co-translational translocation of secretory and membrane proteins, eukaryotic ribosomes dock with the protein conducting channel of the endoplasmic reticulum. An understanding of these processes will require the detailed structure of a eukaryotic ribosome. To this end, we have compared the three-dimensional structures of yeast and rabbit ribosomes at 24 A resolution. In general, we find that the active sites for protein synthesis and translocation have been highly conserved. It is interesting that a channel was visualized in the neck of the small subunit whose entrance is formed by a deep groove. By analogy with the prokaryotic small subunit, this channel may provide a conserved portal through which mRNA is threaded into the decoding center. In addition, both the small and large subunits are built around a dense tubular network. Our analysis further suggests that the nascent chain exit tunnel and the docking surface for the endoplasmic reticulum channel are formed by this network. We surmise that many of these features correspond to rRNA, based on biochemical and structural data. Ribosomal function is critically dependent on the specific association of small and large subunits. Our analysis of eukaryotic ribosomes reveals four conserved inter-subunit bridges with a geometry similar to that found in prokaryotes. In particular, a double-bridge connects the small subunit platform with the interface canyon on the large subunit. Moreover, a novel bridge is formed between the platform and the base of the L1 domain. Finally, size differences between mammalian and yeast large subunit rRNAs have been correlated with five expansion segments that form two large spines and three extended fingers. Overall, we find that expansion segments within the large subunit rRNA have been incorporated at positions distinct from the active sites for protein synthesis and translocation.

Case of enantiomer impurity identification by normal-phase chiral high-performance liquid chromatography with optical rotation and mass spectrometric detection

An impurity produced in the synthesis of compound I is separated and identified as its enantiomer II using normal-phase chiral high-performance liquid chromatography (HPLC) with UV absorbance, optical rotation (OR) and mass spectrometric (MS) detection. The results show that the impurity II and compound I have equal and opposite specific rotations, identical MS spectra and the same MS-MS fragmentation pattern, as required for enantiomers. The procedures presented demonstrate a novel combination of methods for enantiomer identification and characterization that do not require the preparation of individual enantiomer markers or even the racemic mixture, thus reducing the need for additional synthetic work.

The central melanocortin system affects the hypothalamo-pituitary thyroid axis and may mediate the effect of leptin

Prolonged fasting is associated with a downregulation of the hypothalamo-pituitary thyroid (H-P-T) axis, which is reversed by administration of leptin. The hypothalamic melanocortin system regulates energy balance and mediates a number of central effects of leptin. In this study, we show that hypothalamic melanocortins can stimulate the thyroid axis and that their antagonist, agouti-related peptide (Agrp), can inhibit it. Intracerebroventricular (ICV) administration of Agrp (83-132) decreased plasma thyroid stimulating hormone (TSH) in fed male rats. Intraparaventricular nuclear administration of Agrp (83-132) produced a long-lasting suppression of plasma TSH, and plasma T4. ICV administration of a stable alpha-MSH analogue increased plasma TSH in 24-hour-fasted rats. In vitro, alpha-MSH increased thyrotropin releasing hormone (TRH) release from hypothalamic explants. Agrp (83-132) alone caused no change in TRH release but antagonized the effect of alpha-MSH on TRH release. Leptin increased TRH release from hypothalami harvested from 48-hour-fasted rats. Agrp (83-132) blocked this effect. These data suggest a role for the hypothalamic melanocortin system in the fasting-induced suppression of the H-P-T axis.

Preclinical development of keliximab, a Primatized anti-CD4 monoclonal antibody, in human CD4 transgenic mice: characterization of the model and safety studies

The preclinical safety assessment of biopharmaceuticals necessitates that studies be conducted in species in which the products are pharmacologically active. Monoclonal antibodies are a promising class of biopharmaceuticals for many disease indications; however, by design, these agents tend to have limited species cross-reactivity and tend to only be active in primates. Keliximab is a human-cynomolgus monkey chimeric (Primatized) monoclonal antibody with specificity for human and chimpanzee CD4. In order to conduct a comprehensive preclinical safety assessment of this antibody to support chronic treatment of rheumatoid arthritis in patients, a human CD4 transgenic mouse was used for chronic and reproductive toxicity studies and for genotoxic studies. In addition, immunotoxicity studies were conducted in these mice with Candida albicans, Pneumocystis carinii and B16 melanoma cells to assess the effects of keliximab on host resistance to infection and immunosurveillance to neoplasia. The results of these studies found keliximab to be well tolerated with the only effects observed being related to its pharmacologic activity on CD4+ T lymphocytes. The use of transgenic mice expressing human proteins provides a useful alternative to studies in chimpanzees with biopharmaceutical agents having limited species cross-reactivity.

Effect of leptin on hypothalamic GLP-1 peptide and brain-stem pre-proglucagon mRNA

Leptin, the adipocyte-derived plasma hormone, and CNS GLP-1 neurons reduce food intake and body weight. GLP-1 is produced in the CNS by post-translational processing of pre-proglucagon. ICV leptin administration prevented the reduction in hypothalamic GLP-1 peptide content seen in pair-fed food-restricted rats (P < 0.05). There was a significant overall positive correlation between pre-proglucagon mRNA expression in the NTS and hypothalamic GLP-1 peptide content (r = +0.34, P < 0.05). Intraperitoneal leptin administration also increased hypothalamic GLP-1 peptide in food-restricted mice (P < 0. 05). This supports the hypothesis that the anorectic actions of leptin are in part due to stimulation of GLP-1 neurons. Reduced CNS GLP-1 neuronal activity during food deprivation may act to stimulate feeding behaviour, and perhaps also inhibit hypothalamic LHRH neurons, as part of the neuroendocrine response to starvation.

Hypothalamic localization of the feeding effect of agouti-related peptide and alpha-melanocyte-stimulating hormone

The melanocortin-4 receptor (MC4R) in the hypothalamus is thought to be important in physiological regulation of food intake. We investigated which hypothalamic areas known to express MC4R are involved in the regulation of feeding by using alpha-melanocyte-stimulating hormone (alpha-MSH), an endogenous MC4R agonist, and agouti-related peptide (Agrp), an endogenous MC4R antagonist. Cannulae were inserted into the rat hypothalamic paraventricular (PVN), arcuate (Arc), dorsomedial (DMN), and ventromedial (VMN) nuclei; the medial preoptic (MPO), anterior hypothalamic (AHA), and lateral hypothalamic (LHA) areas; and the extrahypothalamic central nucleus of the amygdala (CeA). Agrp (83-132) (0.1 nmol) and [Nle4, D-Phe7]alpha(-MSH (NDP-MSH) (0.1 nmol), a stable alpha-MSH analog, were administered to fed and fasted rats, respectively. The PVN, DMN, and MPO were the areas with the greatest response to Agrp and NDP-MSH. At 8 h postinjection, Agrp increased feeding in the PVN by 218 +/- 23% (P < 0.005), in the DMN by 268 +/- 42% (P < 0.005), and in the MPO by 236 +/- 31% (P < 0.01) compared with a saline control group for each nucleus. NDP-MSH decreased food intake in the PVN by 52 +/- 6% (P < 0.005), in the DMN by 44 +/- 6% (P < 0.0001), and in the MPO by 55 +/- 6% (P < 0.0001) at 1 h postinjection. Injection into the AHA and CeA resulted in smaller alterations in food intake. No changes in feeding were seen after the administration of Agrp into the Arc, LHA, or VMN, but NDP-MSH suppressed food intake in the Arc and LHA. This study indicates that the hypothalamic nuclei expressing MC4R vary in their sensitivity to Agrp and alpha-MSH with regard to their effect on feeding.

A beta and perlecan in rat brain: glial activation, gradual clearance and limited neurotoxicity

A beta1-40 and perlecan (A beta + perlecan) were infused into rat hippocampus for 1 week via osmotic pumps. At the end of the infusion a deposit of A beta immunoreactive material was found surrounding the infusion site. No neurons could be identified within this A beta deposit. The neuron-free area resulting from A beta + perlecan was significantly larger than that found after infusions of A beta40-1 and perlecan (reverse A beta + perlecan), perlecan alone or phosphate-buffered saline vehicle. Following infusion of A beta + perlecan, the glial cells segregated in a manner similar to that associated with compacted amyloid plaques in Alzheimer's disease (AD). Activated microglia/macrophages were prevalent within the A beta deposit while the perimeter of the deposit was delimited by reactive astrocytes. Thioflavin S and Congo red staining indicated a beta-pleated sheet conformation of the A beta deposits, implying formation of fibrils. Intact, apparently healthy neurons were found immediately adjacent to the A beta + perlecan deposit. In contrast, reverse A beta peptide did not form congophilic deposits despite the presence of perlecan. Apoptotic profiles visualized with bisbenzamide or TUNEL staining of fragmented DNA were not seen at any of the infusion sites, yet were readily seen in hippocampal sections from animals treated with kainic acid. At 8 weeks, A beta immunoreactivity, Thioflavin S and Congo red staining was reduced, indicating that A beta was being cleared. There also was no evidence of neuron loss by Nissl or TUNEL staining. The zone of apparent necrosis did not expand between 1 and 8 weeks, and in some instances appeared to contract. The consistency of the A beta + perlecan infusion method in producing reliable A beta amyloid deposits permits estimates of the rate at which fibrillar A beta amyloid can be removed from the brain, and may provide a useful model to study this process in vivo. However, the absence of clearly identifiable degenerating/dying neurons at the 1 or 8 week survival times suggests that either fibrillar A beta + perlecan slowly displaced the brain parenchyma during infusion, or neurons were killed very gradually during the process of clearing the A beta.

Investigation of the feeding effects of melanin concentrating hormone on food intake--action independent of galanin and the melanocortin receptors

Melanin concentrating hormone (MCH) is recognised as a hypothalamic appetite stimulant. The mechanism of action of MCH is undetermined largely due to lack of identification of hypothalamic MCH receptors. We designed in vivo and in vitro studies to further characterise the feeding effects of MCH in the rat. MCH was injected directly into the paraventricular nucleus (PVN) at the beginning of the light phase. PVN MCH (0.5 microg) produced an increase in 2 h food intake of 272+/-60% vs. saline control (0.7+/-0.2 g), p<0.05. The time course of the effect of intracerebroventricular (i.c.v.) administration of 5 microg MCH on food intake was investigated. An increase in feeding was observed within 15 min from the time of injection and was not sustained beyond half an hour following administration. To investigate a possible interaction with galanin, 5 microg of MCH was injected i.c.v. with or without 10 microg of galanin. The two peptides together increased 1 h feeding above that of either peptide alone, 768+/-62% (compared with the saline group, 0.47+/-0.2 g), p<0.05 vs. 585+/-36%, galanin alone and 317+/-72%, MCH alone. Finally, to investigate if MCH bound to the brain melanocortin receptors, receptor autoradiography was performed on rat brain sections with the stable analogue of alpha MSH, [125I] Nle(4), D-Phe(7)-alphaMSH and unlabeled MCH. MCH did not compete with [125I] Nle(4), D-Phe(7)-alphaMSH binding. Results demonstrate that MCH stimulates feeding via the PVN, has a short onset and duration of action and activates feeding by mechanisms independent to galanin and the melanocortin receptors.

Primary biliary cirrhosis and type II autoimmune polyglandular syndrome

A 45-year-old female was diagnosed with Hashimoto's thyroiditis in 1976 and Addison's disease in 1979. At that time, her antimitochondrial antibody (AMA) level was elevated at 1:32. She subsequently developed premature ovarian failure and type I diabetes mellitus. In 1996, she became jaundiced with a cholestatic enzyme pattern. AMA was positive at a titre of 1:256. A liver biopsy confirmed the diagnosis of primary biliary cirrhosis (PBC). She underwent a liver transplantation in January 1998. This is the first report of PBC in association with type II autoimmune polyglandular syndrome. The association of PBC with other organ-specific autoimmune diseases supports an immune-mediated pathogenesis and may have implications in further studies of PBC.

Healthcare utilization associated with dyspepsia in patients with arthritis

OBJECTIVE

To compare gastrointestinal-related healthcare resource utilization in arthritis patients with and without dyspepsia.

STUDY DESIGN

A historical cohort study based on a claims database.

PATIENTS AND METHODS

Data were obtained from the MarketScan database. Adult patients with a diagnosis of arthritis (International Classification of Diseases, 9th Revision [ICD-9] codes 714.0-715.9) during 1992 and 1993 were included; individuals with a diagnosis of dyspepsia within the first 3 months of their arthritis diagnosis were considered study case patients. Each case patient was matched with 4 nondyspeptic arthritis patients based on age, gender, employment status, and type of insurance plan. Healthcare resource utilization in terms of outpatient services and inpatient admissions during the first year after the initial arthritis diagnosis was compared between the case and control groups.

RESULTS

A total of 503 case and 2146 control patients were identified. There were no significant differences in demographic characteristics between the 2 groups. Dyspeptic patients (cases) had a significantly higher rate of claims for endoscopic procedures (odds ratio [OR] = 10.0, P < .01) than nondyspeptic patients (controls). Patients with dyspepsia also had a significantly higher claim rate of gastrointestinal ulcer or bleeding (OR = 4.2, P < .01) and were more likely to be hospitalized at least once (OR = 1.4, P < .01). Dyspeptic patients had overall higher frequencies of use of outpatient services (53.9 vs 32.5 claims per patient, P < .001) and higher costs for both inpatient admission and outpatient services than nondyspeptic patients.

CONCLUSION

Dyspeptic arthritis patients have higher healthcare resource utilization and associated costs than nondyspeptic arthritis patients.

Development and psychometric evaluation of the Environment-Behavior Interaction Code (EBIC)

BACKGROUND

Although the behavioral changes with progressive dementia are seen to increasingly depend on the environmental context until late stage disease, measurement has not reflected this interaction in real time to allow examination of antecedents to disruptive behavior.

OBJECTIVES

To develop and evaluate the psychometric properties of the Environment-Behavior Interaction Code (EBIC) for use in dementia care research with either sequential or nonsequential analyses of behavioral data.

METHOD

Development of the computer-based (sequential event format) EBIC provided an observational coding system to classify all behavior and environmental context in real time, so that the probability of social environmental antecedents to resident disruptive behavior could be estimated. A checklist (interval format) EBIC, based on the same behavioral taxonomy, was developed for clinical outcome research. A total of 158 elderly residents of dementia care units were purposively selected from three large long-term care facilities for the psychometric study components.

RESULTS

Psychometric results indicated significant (p < 0.01) known-groups validity for the disruptive behavior construct, which was defined as a composite of aversive, harmful, and high intensity neutral behavior. Interrater agreement for the event format of the EBIC was estimated by average kappa (0.65) and percentage agreement (78%). For the interval format, the mean interrater kappa was 0.80 with 96% agreement. Stability of the event format using a 2-week retest interval ranged from r= .50 (positive behavior) to r = 0.73 (negative behavior, defined as aversive + harmful). On replication with a new sample, stability was higher for positive (r = 0.92) and negative (r = 0.95) components, and for composite scores of nondisruptive (positive + low intensity neutral; r = 0.65) and disruptive (r= 0.85) behavior.

CONCLUSION

This research provided support for the reliability and validity of both event and interval EBIC formats. Measurement using the EBIC taxonomy has applicability to dementia care research questions that call for either sequential analysis of social interactions or nonsequential analysis of behavioral outcomes in intervention studies.

Rotational symmetry of the C ring and a mechanism for the flagellar rotary motor

FliG, FliM, and FliN, key proteins for torque generation, are located in two rings. The first protein is in the M ring and the last two are in the C ring. The rotational symmetries of the C and M rings have been determined to be about 34 (this paper) and 26 (previous work), respectively. The mechanism proposed here depends on the symmetry mismatch between the rings: the C ring extends 34 levers, of which 26 can bind to the 26 equivalent sites on the M ring. The remaining 8 levers bind to proton-pore complexes (studs) to form 8 torque generators. Movement results from the swapping of stud-bound levers with M ring-bound levers. The model predicts that both the M and C rings rotate in the same direction but at different speeds.

Mice transgenic for a human amyloid precursor protein promoter-lacZ reporter construct

Transgenic mouse lines were generated that expressed a 2-kb amyloid precursor protein (APP) promoter/beta-galactosidase reporter gene construction. In brain, hippocampal pyramidal neurons, neurons in the deeper layers of cerebral cortex, and neurons in several thalamic nuclei were heavily labeled by beta-galactosidase histochemistry. In general, molecular layers and white matter regions did not express the reporter gene. When compared with in situ hybridization for endogenous murine APP RNA, the striatum and outer layers of cerebral cortex had little reporter expression. Thus, the match between reporter expression and endogenous APP expression in brain was not perfect. A similar mismatch between the relative expression of the reporter gene and endogenous APP RNA distribution was found in homogenates from several organs. Although prior work in transgenic mice found similar mismatches in reporter gene distribution, none had tested the APP promoter construct in response to neuronal injury. Kainic acid injections successfully increased murine APP expression in the transgenic mice, but had no effect on the reporter gene expression. Based on these data and those collected by others, we conclude that the 2-kb region upstream of the APP transcription initiation site contains some elements responsible for the tissue-specific expression of this gene, but does not contain all the cis-acting elements sufficient for either the differential tissue distribution of this gene or the regulation of this gene subsequent to neural damage.

'Please see and advise': a qualitative study of patients' experiences of psychiatric outpatient care

BACKGROUND

Patient evaluations have become a sensitive indicator of service delivery and the quality of care. In this study they point to a lack of clarity surrounding the role of outpatient psychiatry in relation to primary care, raising questions about the effective integration of services for patients whose needs straddle the boundaries of primary and specialist care.

METHODS

Interviews with a consecutive series of 100 new referrals to two outpatient clinics compared their expectations of treatment with their subsequent experiences of psychiatric care. Patients' perception of progress was compared with clinical assessments. Follow-up interviews explored the reasons why patients tended to lapse from care.

RESULTS

The majority of patients (74%) hoped for more effective responses to often long-standing problems which had previously been treated with limited success. In approximately one-third of cases this expectation was met; the remainder reported psychiatric intervention was less than helpful (20%), or were unable to say whether it had helped or not. Most of these patients perceived little difference between psychiatric supervision and treatment offered by their GP. Seemingly impersonal consultations and failure to engage with underlying problems contributed to the high drop-out rate.

CONCLUSION

The findings indicate a relatively poor fit between the role of the outpatient service and the circumstances that commonly lead to psychiatric referral. The implications are considered in relation to alternative options for managing psychosocial problems within primary care.

Oral versus transdermal selegiline: antidepressant-like activity in rats

These studies compared the dose-response effects of oral vs. transdermal selegiline on antidepressant-like activity and brain monoamine oxidase (MAO) activities in rats. Rats received selegiline by gavage (0-100 mg/kg) or via transdermal patches (0-4.8 cm2, 0-8.7 mg/kg) daily for 7 days; antidepressant-like activity was determined using the forced-swim test. Following behavioral testing, cerebral cortices were assayed for MAO-A and MAO-B activities. Doses of selegiline that selectively inhibited MAO-B (3 and 10 mg/kg/day by gavage and 0.4 mg/kg/day via patch) did not alter either immobility or latency time. However, the oral administration of 30 or 100 mg/kg/day or the transdermal administration of 8.7 mg/kg/day, doses that led to greater than 70% inhibition of MAO-A, decreased immobility time significantly. The IC50s for inhibition of MAO-A following oral and transdermal administration for 7 days were 19.8 and 1.1 mg/kg, respectively. Results indicate that both oral and transdermal selegiline have antidepressant-like activity as assessed by the forced-swim test, and that transdermal administration, which bypasses first-pass metabolism, allows for using lower doses than oral administration.

Induction of presenilins in the rat brain after middle cerebral arterial occlusion

In the present study, we have examined the expression of both presenilins in the rat hippocampus, cortex, striatum, and cerebellum after middle cerebral artery occlusion (MCA-O), an animal model of ischemia. The cortex showed the greatest increase in PS mRNA levels (7-10-fold) at 4 and 8 days posttreatment. Presenilin-1 (PS-1) levels in the contralateral cortex were significantly increased 1 day after MCA-O. In comparison, PS mRNA content was only modestly elevated in the hippocampus and striatum at 4 and 8 days after MCA-O (30-100% changes). Other Alzheimer's disease (AD)-related genes, amyloid precursor protein and apolipoprotein E, are induced in brain injury suggesting that these AD-related genes may well be components of a brain-injury response. Thus, a breakdown in this response via cerebrovascular disease and/or genetic mutation may contribute to AD pathology.

The physical environment of special care units: needs of residents with dementia from the perspective of staff and family caregivers

To manage the care of increasing numbers of residents with dementia, many long-term care facilities have created special care units (SCUs) designed to meet the unique needs of this group. This article describes results of the qualitative component of a larger research project examining environment-behavior relationships in dementia care settings. Eighteen indepth interviews were conducted with 9 staff and 9 family members of SCU residents. Thematic analysis was conducted using grounded theory techniques. Participants described residents' needs in relation to both the physical and social environments. This article focuses on the five areas of need identified by participants in relation to the physical environment: safety, homelike setting, optimal stimulation, cues, and options for privacy and social interaction.

Inhibition of glucose stimulated insulin secretion by neuropeptide Y is mediated via the Y1 receptor and inhibition of adenylyl cyclase in RIN 5AH rat insulinoma cells

Neuropeptide Y (NPY) has been shown to inhibit insulin secretion from the islets of Langerhans. We show that insulin secretion in the insulinoma cell line RIN 5AH is inhibited by NPY. 125I-Peptide YY (PYY) saturation and competition-binding studies using NPY fragments and analogues on membranes prepared from this cell line show the presence of a single class of NPY receptor with a Y1 receptor subtype-like profile. Inhibition of insulin secretion in this cell line by NPY fragments and analogues also shows a Y1 receptor-like profile. Both receptor binding and inhibition of insulin secretion showed the same orders of potency with NPY > [Pro34]-NPY > NPY 3-36 >> NPY 13-36. The Y1 receptor antagonist, BIBP 3226, blocks NPY inhibition of insulin secretion from, and inhibits 125I-PYY binding to, RIN 5AH cells. Northern blot analysis using a Y1-receptor specific probe shows that NPY Y1 receptors are expressed by RIN 5AH cells. Y5 receptors are not expressed in this cell line. Neuropeptide Y inhibition of insulin secretion is blocked by incubation with pertussis toxin, implying that the effect is via a G-protein (Gi or Go) coupled receptor. Neuropeptide Y inhibits the activation of adenylyl cyclase by isoprenaline in RIN 5AH cell lysates, and the stimulation of cAMP by glucagon-like peptide-1 (7-36) amide (GLP-1). It also blocks insulin secretion stimulated by GLP-1, but not by dibutyryl cyclic AMP. Hence, we suggest that NPY inhibits insulin secretion from RIN 5AH cells via a Y1 receptor linked through Gi to the inhibition of adenylyl cyclase.

A C-terminal fragment of Agouti-related protein increases feeding and antagonizes the effect of alpha-melanocyte stimulating hormone in vivo

Agouti-related protein (Agrp) is present in rat and human hypothalamus and is structurally related to agouti protein. Overexpression of either of these proteins results in obesity. However the effect of exogenous Agrp and its in vivo interaction with alpha-melanocyte stimulating hormone (alphaMSH), the likely endogenous melanocortin 3 and 4 receptor (MC3-R and MC4-R) agonist, have not been demonstrated. We report that 1 nmol of Agrp(83-132), a C-terminal fragment of Agrp, when administered intracerebroventricularly (ICV) into rats, increased food intake over a 24-h period (23.0+/-1.4 g saline vs 32.9+/-2.3 g Agrp, p<0.05). The hyperphagia was similar to that seen when 1 nmol of the synthetic MC3-R and MC4-R antagonist SHU9119 was given i.c.v. (19.6+/-1.8 g saline vs 32.5+/-1.7 g SHU9119, p<0.001). Both Agrp(83-132) and SHU9119 blocked the reduction in 1-h food intake of i.c.v. alphaMSH at the beginning of the dark phase. This effect occurred independently of whether the antagonists were administered simultaneously, or nine hours prior, to the alphaMSH. We have also shown Agrp(83-132) is an antagonist at the MC3-R and MC4-R, with similar inhibition of cAMP activation to that previously reported for the full length peptide. In conclusion, Agrp(83-132) administered i.c.v. increases feeding with long lasting effects and is able to inhibit the action of alphaMSH. This interaction may be mediated by the MC3-R and/or MC4-R.

The NPY Y1 receptor antagonist BIBP 3226 blocks NPY induced feeding via a non-specific mechanism

We have previously shown that intracerebroventricular BIBP 3226 inhibits NPY induced feeding in rats. However, this was associated with abnormal behaviour, likely to be due to interaction with Y1 receptors involved in mechanisms other than the control of food intake. In order to minimise such interactions we investigated the effects of paraventricular nucleus (PVN) injections of BIBP 3226 and its inactive enantiomer BIBP 3435. Intra-PVN injection of NPY (0.1-2.5 nmol/animal) increased food intake, with an EC50 of approximately 0.15 nmol/animal. Injections of BIBP 3226 and BIBP 3435 (0.25-25 nmol) reduced NPY-induced food intake in a dose responsive manner, with BIBP 3226 reducing food intake by 95%, and BIBP 3435 by 65% at the highest dose tested. The reversibility of the effect of BIBP 3226 was investigated by measuring the feeding response to NPY (0.5 nmol) in animals 1 week after BIBP 3226 injection. The response to NPY was less in animals which had received high doses of BIBP 3226. Animals previously injected with saline vehicle alone showed a normal NPY feeding response. These results suggest that BIBP 3226 may be inhibiting NPY-induced food intake in a non-specific manner, not secondary to inhibition of the Y1 receptor. This does not, however rule out a role for the Y1 receptor in the control of food intake by NPY.

Glucagon-like peptide-1 stimulates luteinizing hormone-releasing hormone secretion in a rodent hypothalamic neuronal cell line

To examine the influence of the putative satiety factor (GLP-1) on the hypothalamo-pituitary-gonadal axis, we used GT1-7 cells as a model of neuronal luteinizing hormone- releasing hormone (LHRH) release. GLP-1 caused a concentration-dependent increase in LHRH release from GT1-7 cells. Specific, saturable GLP-1 binding sites were demonstrated on these cells. The binding of [125I]GLP-1 was time-dependent and consistent with a single binding site (Kd = 0.07+/-0.016 nM; binding capacity = 160+/-11 fmol/mg protein). The specific GLP-1 receptor agonists, exendin-3 and exendin-4, also showed high affinity (Ki = 0.3+/-0.05 and 0.32+/-0.06 nM, respectively) as did the antagonist exendin-(9-39) (Ki = 0.98+/-0.24 nM). At concentrations that increased LHRH release, GLP-1 (0.5-10 nM) also caused an increase in intracellular cAMP in GT1-7 cells (10 nM GLP-1: 7.66+/-0.4 vs. control: 0.23+/-0.02 nmol/mg protein; P < 0.001). Intracerebroventricular injection of GLP-1 at a single concentration (10 microg) produced a prompt increase in the plasma luteinizing hormone concentration in male rats (GLP-1: 1.09+/-0.11 vs. saline: 0.69+/-0.06 ng/ml; P < 0.005). GLP-1 levels in the hypothalami of 48-h-fasted male rats showed a decrease, indicating a possible association of the satiety factor with the low luteinizing hormone levels in animals with a negative energy balance.

Exaggerated astrocyte reactivity after nigrostriatal deafferentation in the aged rat

Although clinical experience suggests that brain injury in the aged is associated with a poor prognosis, little research has examined this phenomenon at a cellular or molecular level. Unilateral 6-hydroxydopamine lesions of the nigrostriatal system were produced in 6-, 15- or 24-month-old rats. In the deafferented neostriatum, the time-dependent induction of glial fibrillary acidic protein (GFAP) was larger and persisted longer in the aged rats. The response of middle-aged rats was intermediate. In contrast, no induction of S-100 or glutamine synthetase was observed in any age group. In a second series of rats with stab wounds in the neostriatum, there were substantially larger GFAP inductions than after deafferentation, but fewer effects of age. However, in both lesion paradigms, GFAP staining increased in the contralateral striatum of old rats, but not in young rats. These data support and extend our earlier work describing larger GFAP RNA inductions after fornix transections in aged mouse hippocampus. The consistency of this exaggerated glial reactivity in the aged brain after modest injury suggests the following: 1) aged astrocytes are more sensitive to gliotrophic factors released by terminal degeneration, 2) larger quantities of such factors are produced after injury, 3) clearance of these factors is delayed in old rodents, and/or 4) aged astrocytes are less able to terminate GFAP inductions after activation. Given the potential role of inflammatory reactions as pathogenic mechanisms in Alzheimer's dementia, these data suggest that age-related glial hypersensitivity may independently increase the risk for some degenerative diseases.

Peptide analogue studies of the hypothalamic neuropeptide Y receptor mediating pituitary adrenocorticotrophic hormone release

Hypothalamic neuropeptide Y (NPY) is thought to be important in the regulation of feeding and also in the release of Adrenocorticotrophic hormone (ACTH). Intracerebroventricular administration of NPY to male rats significantly increased plasma ACTH 10 min after injection and stimulated 2-h food intake. A series of analogues of NPY that have a greatly reduced affinity for the Y1 [human pancreatic polypeptide (human PP), NPY(3-36)], the Y2 ([Pro34]NPY, human PP), the Y3 (peptide YY), and the Y6 (human PP) receptor, all markedly stimulated ACTH release. Rat PP, which binds with high affinity to the Y4 receptor, was unable to stimulate ACTH release. A novel analogue fragment [Pro34]NPY(13-36) was synthesized as a ligand with low Y1 and Y2 receptor affinity. Interestingly, neither [Pro34]NPY(13-36) nor the selective Y5 receptor agonist [D-Trp32]NPY stimulated food intake, whereas both significantly increased plasma ACTH. Thus the hypothalamic NPY receptor mediating increases in plasma ACTH has a fragment activation profile unlike the Y1-Y4 or Y6 receptors and appears distinct from the NPY receptor controlling food intake.

Regional and cellular localization of presenilin-2 RNA in rat and human brain

In situ hybridization probes selective for presenilin-2 (PS-2) were used to determine the regional and cellular expression pattern of PS-2 mRNA in rat and human brain. In rat brain, the greatest expression of PS-2 mRNA is in the granule cell layers of the dentate gyrus and cerebellum. Molecular layers within these structures are virtually devoid of signal. Cortical expression of PS-2 message is restricted to neuronal layers, while the hybridization signal is weak or absent in molecular layers and white matter. Kidney, liver, and spleen display moderate levels of PS-2 message. A PS-2 sense strand probe produced no specific signals in any tissue. In human brain, the greatest hybridization signal for PS-2 is present in the granule cells of the cerebellum. Within hippocampus, the granule cell layer of dentate is strongly labeled, with CA3 pyramidal neurons also clearly visible. A laminar expression pattern is seen in the neuronal layers of human frontal and temporal cortex, with the deeper laminae having the strongest signals. These data are consistent with a primarily neuronal localization of PS-2 mRNA within the brains of both rat and human. Within the limitations of the analysis, it appears that virtually every neuron is labeled, and differences in the intensity of labeling are associated with both neuron size/density and brain region. The distribution of PS-2 RNA is not restricted to those regions having the greatest pathology in Alzheimer's disease. However, one unusual pathological feature of PS-2 mutations causing AD is the presence of cerebellar amyloid plaques in some cases. It is intriguing, in this context, that PS-2 RNA is enriched in the cerebellum, especially in human specimens.

Neuropeptide Y induced feeding in the rat is mediated by a novel receptor

There are now six recognized neuropeptide Y (NPY) receptor subtypes (Y1-Y4 and two recently cloned distinct receptors labeled Y5), of which Y1 and one of the Y5's have been suggested could mediate the effect of NPY on feeding. The fragments NPY(2-36) and NPY(3-36), which bind Y1 only poorly, were injected intracerebroventricularly (icv) and found to have similar dose-response relationships to NPY in the stimulation of feeding. However NPY (13-36), which stimulates both Y2 and Y5, caused no increase in food intake, even at high doses. Maximal stimulation with the classical Y1 agonist [Pro34]-NPY produced only 50% of the maximum effect of NPY itself despite fully inhibiting adenylyl cyclase activity in vitro in a Y1 system. The novel fragment [Pro34]-NPY(3-36) is as effective at stimulating food intake as the classical Y1 analogue [Pro34]-NPY but bound to the Y1 receptor with only 1/20th of the affinity of NPY and failed to inhibit adenylyl cyclase through this receptor. [Pro34]-NPY(3-36) is therefore a relatively appetite-selective ligand. Coadministration of high dose NPY(13-36) and [Pro34]NPY did not enhance feeding compared with [Pro34]-NPY alone. In addition, the NPY Y1 receptor antagonist BIBP-3226, which does not bind Y2, Y4, or Y5 receptors, significantly reduced NPY induced feeding. These results indicate that the feeding effect of icv NPY involves a novel receptor and that it is functionally distinct from the recognized receptor subtypes.