Increased acetylcholine and glutamate efflux in the prefrontal cortex following intranasal orexin‐A (hypocretin‐1)

Orexin/hypocretin neurons of the lateral hypothalamus and perifornical area are integrators of physiological function. Previous work from our laboratory and others has shown the importance of orexin transmission in cognition. Age‐related reductions in markers of orexin function further suggest that this neuropeptide may be a useful target for the treatment of age‐related cognitive dysfunction. Intranasal administration of orexin‐A (OxA) has shown promise as a therapeutic option for cognitive dysfunction. However, the neurochemical mechanisms of intranasal OxA administration are not fully understood. Here, we use immunohistochemistry and in vivo microdialysis to define the effects of acute intranasal OxA administration on: (i) activation of neuronal populations in the cortex, basal forebrain, and brainstem and (ii) acetylcholine (AC h) and glutamate efflux in the prefrontal cortex (PFC ) of Fischer 344/Brown Norway F1 rats. Acute intranasal administration of OxA significantly increased c‐Fos expression, a marker for neuronal activation, in the PFC and in subpopulations of basal forebrain cholinergic neurons. Subsequently, we investigated the effects of acute intranasal OxA on neurotransmitter efflux in the PFC and found that intranasal OxA significantly increased both AC h and glutamate efflux in this region. These findings were independent from any changes in c‐Fos expression in orexin neurons, suggesting that these effects are not resultant from direct activation of orexin neurons. In total, these data indicate that intranasal OxA may enhance cognition through activation of distinct neuronal populations in the cortex and basal forebrain and through increased neurotransmission of AC h and glutamate in the PFC .

     

Plant community structure,connectance, niche limitation and species guilds within a dune slack grassland

Species phytomass in 40 mm×40 mm quadrats was used to examine community structure in four homogeneous areas of vegetation in sand dune slacks. There were from 9 to 16 common species in the samples, and most parameters of community structure were found to relate consistently to species number. We used covariance between all species at increasing dimensions of aggregations of quadrats to suggest that sociological interaction between species existed at scales of around 200 mm diameter. Generalised variance was of no help in this enquiry. We show that a connectance estimation arrived at from these parameters is, although a real feature of the analysis, apparently unrelated to connectance as understood in the food web literature. There is strong evidence that guild structure, sociological interaction and niche limitation increase with increasing number of species present, so that most diverse assemblage can be said to have a definite community structure.     

Optimization of pectin extraction from lemon by-product with acidified date juice using response surface methodology

Response surface methodology was used to optimize pectin recovery from lemon by-product using an acidified date juice as extraction solution. When enriched in pectin, this latter can be useful for preparation of date-lemon jelly. The effects of three parameters namely temperature, pH and extraction time, on pectin extraction were studied. The fitted mathematical model allowed us to plot response surfaces as well as isoresponse curves and to determine optimal extraction conditions. Results clearly indicated that the temperature was the main factor influencing the pectin yield which increased with temperature and time or decreasing pH. The selected optimal conditions were: temperature 84.34 °C; extraction time 3 h 34 min and pH 2.8. These conditions yielded about 11.21% of pectin versus 10.89% for the predicted value.     

Restitution of defective glucose-stimulated insulin release of sulfonylurea type 1 receptor knockout mice by acetylcholine

Inhibition of ATP-sensitive K+ (K(ATP)) channels by an increase in the ATP/ADP ratio and the resultant membrane depolarization are considered essential in the process leading to insulin release (IR) from pancreatic beta-cells stimulated by glucose. It is therefore surprising that mice lacking the sulfonylurea type 1 receptor (SUR1-/-) in beta-cells remain euglycemic even though the knockout is expected to cause hypoglycemia. To complicate matters, isolated islets of SUR1-/- mice secrete little insulin in response to high glucose, which extrapolates to hyperglycemia in the intact animal. It remains thus unexplained how euglycemia is maintained. In recognition of the essential role of neural and endocrine regulation of IR, we evaluated the effects of acetylcholine (ACh) and glucagon-like peptide-1 (GLP-1) on IR and free intracellular Ca2+ concentration ([Ca2+]i) of freshly isolated or cultured islets of SUR1-/- mice and B6D2F1 controls (SUR1+/+). IBMX, a phosphodiesterase inhibitor, was also used to explore cAMP-dependent signaling in IR. Most striking, and in contrast to controls, SUR1-/-) islets are hypersensitive to ACh and IBMX, as demonstrated by a marked increase of IR even in the absence of glucose. The hypersensitivity to ACh was reproduced in control islets by depolarization with the SUR1 inhibitor glyburide. Pretreatment of perifused SUR1-/- islets with ACh or IBMX restored glucose stimulation of IR, an effect expectedly insensitive to diazoxide. The calcium channel blocker verapamil reduced but did not abolish ACh-stimulated IR, supporting a role for intracellular Ca2+ stores in stimulus-secretion coupling. The effect of ACh on IR was greatly potentiated by GLP-1 (10 nM). ACh caused a dose-dependent increase in [Ca2+]i at 0.1-1 microM or biphasic changes (an initial sharp increase in [Ca2+]i followed by a sustained phase of low [Ca2+]i) at 1-100 microM. The latter effects were observed in substrate-free medium or in the presence of 16.7 mM glucose. We conclude that SUR1 deletion depolarizes the beta-cells and markedly elevates basal [Ca2+]i. Elevated [Ca2+]i in turn sensitizes the beta-cells to the secretory effects of ACh and IBMX. Priming by the combination of high [Ca2+]i, ACh, and GLP-1 restores the defective glucose responsiveness, precluding the development of diabetes but not effectively enough to cause hyperinsulinemic hypoglycemia.     

A functional classification for predicting the dynamics of landscapes

Abstract. Functional classifications have been derived for various purposes using subjective, objective and deductive approaches. Most of the classifications were derived to describe a static state of a region or landscape rather than to predict the dynamics of the system. Here, we suggest a simple, but comprehensive functional classification based on life history parameters that can predict the dynamics of plant communities subject to recurrent disturbances. The predicted dynamics are described in terms of survival and local extinction of the functional groups. The groups derived from the classification are probably largely independent of functional groupings that may be derived for other aspects of community composition (e.g. structure, phenology) and community interactions (roughness, albedo etc.). We emphasize that functional classification is context-dependent and we should not expect to find a useful, universal classification into functional groups. Software has been developed to help classify the species into functional groups, to derive successional sequences and to predict community composition under different disturbance regimes both in point and landscape models.     

Breast cancer in young women in southern Tunisia: Anatomical study and clinical prognostic factors: About a series of 83 patients

Purpose

To define epidemiological, clinical, therapeutic and prognostic factors influencing survival of breast cancer in young women younger than 35 in southern Tunisia.

Material and methods

This is a retrospective study of 83 patients younger than 35 years and treated within tumors mammary committee of Sfax.

Results

The mean age was 31.7 years. T2 stage, high grade with positive node tumors were frequent. Breast surgery was performed for 73 patients. Chemotherapy was neo-adjuvant, adjuvant and palliative for respectively 10, 62 and 13 patients. Radiotherapy was delivered for 65 patients with curative intent and for 8 metastatic patients. Endocrine therapy was adjuvant in 38 patients and palliative in 6 cases. The overall survival (OS) at 5 years was 66.8%. Pejorative prognostic factors in uni-variate analysis were clinical T stage (T3, T4), and the number of involved lymph nodes.

Conclusion

Despite adequate treatment, the prognosis of breast cancer in young women remains worse. Early diagnosis is necessary to promote outcome.     

Obesity and Association with Area of Residence,Gender and Socio-Economic Factors in Algerian and Tunisian Adults

Introduction

The epidemiological transition has resulted in a major increase in the prevalence of obesity in North Africa. This study investigated differences in obesity and its association with area of residence, gender and socio-economic position among adults in Algeria and Tunisia, two countries with socio-economic and socio-cultural similarities.

Methods

Cross-sectional studies used stratified, three-level, clustered samples of 35–70 year old adults in Algeria, (women n = 2741, men n = 2004) and Tunisia (women n = 2964, men n = 2379). Thinness was defined as Body Mass Index (BMI) = weight/height <18.5 kg/m², obesity as BMI ≥30, and abdominal obesity as waist circumference/height ≥0.6. Associations with area of residence, gender, age, education, profession and household welfare were assessed.

Results

Prevalence of thinness was very low except among men in Algeria (7.3% C.I.[5.9–8.7]). Prevalence of obesity among women was high in Algeria (30.1% C.I.[27.8–32.4]) and Tunisia (37.0% C.I.[34.4–39.6]). It was less so among men (9.1% C.I.[7.1–11.0] and 13.3% C.I.[11.2–15.4]).The results were similar for abdominal obesity. In both countries women were much more obesity-prone than men: the women versus men obesity Odds-Ratio was 4.3 C.I.[3.4–5.5] in Algeria and 3.8 C.I.[3.1–4.7] in Tunisia. Obesity was more prevalent in urban versus rural areas in Tunisia, but not in Algeria (e.g. for women, urban versus rural Odds-Ratio was 2.4 C.I.[1.9–3.1] in Tunisia and only 1.2 C.I.[1.0–5.5] in Algeria). Obesity increased with household welfare, but more markedly in Tunisia, especially among women. Nevertheless, in both countries, even in the lowest quintile of welfare, a fifth of the women were obese.

Conclusion

The prevention of obesity, especially in women, is a public health issue in both countries, but there were differences in the patterning of obesity according to area of residence and socio-economic position. These specificities must be taken into account in the management of obesity inequalities.     

Life history,excystment features,and growth characteristics of the Mediterranean harmful dinoflagellate Alexandrium pseudogonyaulax

Studies considering the biology and ecology of the toxic bloom‐forming species, Alexandrium pseudogonyaulax, are rare. Our results highlight five features not described before in A. pseudogonyaulax life cycle: (i) A. pseudogonyaulax gametes showed two modes of conjugation, anisogamy and isogamy, (ii) sexual conjugation occurs either in the dark or in the light phase by engulfment or a fusion process, (iii) the presence of planozygote and newly formed cysts in monoclonal culture suggests homothallism, (iv) newly formed cysts have very dark vesicular content and are mostly unparatabulated when observed under light microscope and (v) natural resting cysts are able to give either a planomeiocyte or two vegetative cells. Cyst viability was enhanced after 5 months of cold storage (4°C), with excystment rate reaching 97% after 3 d of incubation. Excystment rate was highest (43%–79%) in Enriched Natural Sea Water diluted culture medium, whereas few germling cells were able to survive without the culture medium (0%–13%). Salinity‐irradiance experiments revealed that the highest cell concentrations occur at high irradiances for all the tested salinities. Vegetative growth rates generally increased with increasing irradiance, and were less dependent on salinity variations. The relatively low growth rate, low cell densities in the laboratory, and the notable capacity of producing cysts along growth phases of A. pseudogonyaulax could explain the occurrence of high resting cysts densities in the sediment of Bizerte lagoon and the relatively low abundances of vegetative cells in the water column.     

The effect of post-lunch napping on mood,reaction time,and antioxidant defense during repeated sprint exercice

To compare the effects of two nap opportunities (20 and 90 min) to countermeasure the transient naturally occurring increased sleepiness and decreased performances during the post-lunch dip (PLD). Fourteen highly trained judokas completed in a counterbalanced and randomized order three test sessions (control (No-nap), 20- (N20) and 90-min (N90) nap opportunities). Test sessions consisted of the running-based anaerobic sprint test (RAST), simple and multiple-choice reaction times (MCRT) and the Epworth sleepiness scale (ESS). From the RAST, the maximum (P_max), mean (P_mean) and minimum (P_min) powers were calculated. Blood samples were taken before and after the RAST to measure the effect of pre-exercise napping on energetic and muscle damage biomarkers and antioxidant defense. N20 increased P_max and P_mean compared to No-nap (p < 0.001, d = 0.59; d = 0.66) and N90 (p < 0.001, d = 0.98; d = 0.72), respectively. Besides, plasma lactate and creatinine increased only when the exercise was performed after N20. Both N20 (p < 0.001, d = 1.18) and N90 (p < 0.01, d = 0.78) enhanced post-exercise superoxide dismutase activity compared to No-nap. However, only N20 enhanced post-exercise glutathione peroxidase activity (p < 0.001, d = 1.01) compared to pre-nap. Further, MCRT performance was higher after N20 compared to No-nap and N90 (p < 0.001, d = 1.15; d = 0.81, respectively). Subjective sleepiness was lower after N20 compared to No-nap (p < 0.05, d = 0.92) and N90 (p < 0.01, d = 0.89). The opportunity to nap for 20 min in the PLD enhanced RAST, MCRT performances, and antioxidant defense, and decreased sleepiness. However, the opportunity of 90 min nap was associated with decreased repeated sprint performances and increased sleepiness, probably because of the sleep inertia.     

The effect of spatial scale on evenness

Abstract. The effect of spatial scale on species evenness has not previously been investigated. As the area of each sample of vegetation (i.e. the spatial grain) increases, evenness could in theory increase, decrease, or stay the same, though the simplest model predicts an increase. We use biomass data from four dune slack sites and two semi-arid grasslands, sampled to allow calculation of evenness at a range of spatial grains. In all six sites, evenness decreases as grain size increases, almost monotonically. It is hypothesized that such a pattern is a result of a general feature of plant species abundance distributions and of vegetation response to environmental microheterogeneity.