The effect of short-term fluctuations in pH on NO−3 uptake and intracellular constituents in Skeletonemacostatum (Grev.) Cleve

Measurements of uptake rates, intracellular nitrogen pools, and other key intracellular constituents were made during exponential growth in Skeletonema costatum (Grev.) Cleve under varying pH levels. An understanding of the overall effects of extracellular pH on the above mentioned cellular parameters is crucial in order to ascertain the degree to which pH must be regulated and monitored in laboratory experiments with marine phytoplankton.It was found that uptake rates and intracellular pool sizes of NO^?₃ were directly influenced by the extracellular pH level, whereas, other cellular compounds remained relatively unchanged. Therefore, nitrogen uptake and intracellular nitrogen storage are dependent on key H⁺ and OH_? ion transport mechanisms that are associated with phytoplankton metabolism. These findings reiterate the fact that investigators examining nitrogen uptake and assimilatory mechanisms in marine phytoplankton must be conscious of cellular H ⁺ and OH^? fluxes that contribute to intracellular pH regulation and changes in extracellular pH levels, both of which interact to affect phytoplankton metabolic processes.     

Neuropeptide Y and catecholamine release in the piglet during hypoxia: enhancement by theophylline.

Sympathoadrenal activity was studied in 13 young piglets during hypoxia. The piglets were anaesthetized with chloralose/urethane, tracheostomized, paralyzed with gallamine and artificially ventilated. A femoral artery catheter was inserted and used for blood sampling. The piglets were challenged with 6 min of 6% CO2, 10 min of 12% O2 and 6 min of 6% O2 before and after theophylline (an adenosine receptor antagonist) treatment 20 mg/kg (n = 9) or saline (n = 4). Plasma samples were obtained before, during and after each hypercapnic or hypoxic period and analysed for their content of noradrenaline, adrenaline and neuropeptide Y. Hypercapnia with 6% CO2 and moderate hypoxia with 12% O2 did not lead to any significant increase of either noradrenaline (NA), adrenaline (A) or neuropeptide Y (NPY). However, severe hypoxia with 6% O2 increased the NA level from 30 to 66 nmol/l; the A level from 1 to 28 nmol/l and NPY from 140 to 213 pmol/l. After treatment with theophylline the baseline NA increased from 27 to 40 nmol/l, A rom 1.5 to 4.0 and NPY concentration from 65 to 171 pmol/l. Theophylline moderately enhanced the release of NPY, NA and A during the 12% O2 challenge. However, during the severe hypoxia (6%), the increase of NA (from 49 to 333 nmol/l), A (from 8 to 214 nmol/l) and NPY (from 184 to 385 pmol/l) showed considerably enhancement after the theophylline treatment. The results obtained before and after saline were similar showing that the duration of the experiments per se did not change the baseline levels or the effect of the challenges on NA, A or NPY levels.(ABSTRACT TRUNCATED AT 250 WORDS)     

Are cultured human myotubes far from home?

Satellite cells can be isolated from skeletal muscle biopsies, activated to proliferating myoblasts and differentiated into multinuclear myotubes in culture. These cell cultures represent a model system for intact human skeletal muscle and can be modulated ex vivo. The advantages of this system are that the most relevant genetic background is available for the investigation of human disease (as opposed to rodent cell cultures), the extracellular environment can be precisely controlled and the cells are not immortalized, thereby offering the possibility of studying innate characteristics of the donor. Limitations in differentiation status (fiber type) of the cells and energy metabolism can be improved by proper treatment, such as electrical pulse stimulation to mimic exercise. This review focuses on the way that human myotubes can be employed as a tool for studying metabolism in skeletal muscles, with special attention to changes in muscle energy metabolism in obesity and type 2 diabetes.     

Repeated oral administration of capsaicin increases anxiety-like behaviours with prolonged stress-response in rats

This study was conducted to examine the psycho-emotional effects of repeated oral exposure to capsaicin, the principal active component of chili peppers. Each rat received 1 mL of 0.02% capsaicin into its oral cavity daily, and was subjected to behavioural tests following 10 daily administrations of capsaicin. Stereotypy counts and rostral grooming were significantly increased, and caudal grooming decreased, in capsaicin-treated rats during the ambulatory activity test. In elevated plus maze test, not only the time spent in open arms but also the percent arm entry into open arms was reduced in capsaicin-treated rats compared with control rats. In forced swim test, although swimming duration was decreased, struggling increased in the capsaicin group, immobility duration did not differ between the groups. Repeated oral capsaicin did not affect the basal levels of plasma corticosterone; however, the stress-induced elevation of plasma corticosterone was prolonged in capsaicin treated rats. Oral capsaicin exposure significantly increased c-Fos expression not only in the nucleus tractus of solitarius but also in the paraventricular nucleus. Results suggest that repeated oral exposure to capsaicin increases anxiety-like behaviours in rats, and dysfunction of the hypothalamic-pituitary-adrenal axis may play a role in its pathophysiology.     

Effect of weight loss and exercise on angiogenic factors in the circulation and in adipose tissue in obese subjects

Background:

Vascular growth is a prerequisite for adipose tissue (AT) development and expansion. Some AT cytokines and hormones have effects on vascular development, like vascular endothelial growth factor (VEGF‐A), angiopoietin (ANG‐1), ANG‐2 and angiopoietin‐like protein‐4 (ANGPTL‐4).

Methods:

In this study, the independent and combined effects of diet‐induced weight loss and exercise on AT gene expression and proteins levels of those angiogenic factors were investigated. Seventy‐nine obese males and females were randomized to: 1. Exercise‐only (EXO; 12‐weeks exercise without diet‐restriction), 2. Hypocaloric diet (DIO; 8‐weeks very low energy diet (VLED) + 4‐weeks weight maintenance diet) and 3. Hypocaloric diet and exercise (DEX; 8‐weeks VLED + 4‐weeks weight maintenance diet combined with exercise throughout the 12 weeks). Blood samples and fat biopsies were taken before and after the intervention.

Results:

Weight loss was 3.5 kg in the EXO group and 12.3 kg in the DIO and DEX groups. VEGF‐A protein was non‐significantly reduced in the weight loss groups. ANG‐1 protein levels were significantly reduced 22‐25% after all three interventions (P < 0.01). The ANG‐1/ANG‐2 ratio was also decreased in all three groups (P < 0.05) by 27‐38%. ANGPTL‐4 was increased in the EXO group (15%, P < 0.05) and 9% (P < 0.05) in the DIO group. VEGF‐A, ANG‐1, and ANGPTL‐4 were all expressed in human AT, but only ANGPTL‐4 was influenced by the interventions.

Conclusions:

Our data show that serum VEGF‐A, ANG‐1, ANG‐2, and ANGPTL‐4 levels are influenced by weight changes, indicating the involvement of these factors in the obese state. Moreover, it was found that weight loss generally was associated with a reduced angiogenic activity in the circulation.     

Effect of chronic treatment with Rosiglitazone on Leydig cell steroidogenesis in rats: <Emphasis Type="Italic">In vivo</Emphasis> and <Emphasis Type="Italic">ex vivo</Emphasis> studies

Background  

The present study was designed to examine the effect of chronic treatment with rosiglitazone - thiazolidinedione used in the treatment of type 2 diabetes mellitus for its insulin sensitizing effects - on the Leydig cell steroidogenic capacity and expression of the steroidogenic acute regulatory protein (StAR) and cholesterol side-chain cleavage enzyme (P450scc) in normal adult rats.     

Pap smear screening in women under 30 in the Norwegian Coordinated Cervical Cancer Screening Program, with a comparison of immediate biopsy vs Pap smear triage of moderate dysplasia

OBJECTIVE: Top provide population based estimates of Pap smear screening results among women under 30 and to compare the outcomes of 2 triage options for women under 30 with a moderate dysplastic Pap smear: immediate biopsy vs. Pap smear follow-up. STUDY DESIGN: All Pap smears, histologically verified cervical intraepithelial lesion (CIN) 2/3 and invasive cervical cancer in 1999-2002 from women in Norway under 30 in 2000-2002 were analyzed. Due to different triage recommendations in different laboratories, 836 women under 30 with a moderately dysplastic Pap smear were recommended for immediate biopsy, while 109 were recommended for a Pap smear within 6 months. Risk estimates for triage outcome were estimated by multinominal logistic regression. RESULTS: The prevalence of squamous intraepithelial lesion was highest around 20 years. The first moderate dysplasia was diagnosed at age 16, as was CIN 2/3. Of the women with Pap smear triage, one third were diagnosed with a CIN 2+ lesion, one third had a normal outcome, while the last third were in uncertain state 12 months later. Among those recommended for immediate biopsy, nearly 70% were diagnosed with a CIN 2+, thus having odds of 4.2 (95% CI 2.5-7.1) higher than did women with Pap smear triage of being diagnosed with CIN2+ 12 months later. CONCLUSION: The choice of triage has a profound impact on the proportion of young women diagnosed with CIN 2+ after a moderately dysplastic Pap smear.     

A phosphatidylinositol 3-kinase class III sub-complex containing VPS15, VPS34, Beclin 1, UVRAG and BIF-1 regulates cytokinesis and degradative endocytic traffic

The mammalian class III phosphatidylinositol 3-kinase (PI3K-III) complex regulates fundamental cellular functions, including growth factor receptor degradation, cytokinesis and autophagy. Recent studies suggest the existence of distinct PI3K-III sub-complexes that can potentially confer functional specificity. While a substantial body of work has focused on the roles of individual PI3K-III subunits in autophagy, functional studies on their contribution to endocytic receptor downregulation and cytokinesis are limited. We therefore sought to elucidate the specific nature of the PI3K-III complexes involved in these two processes. High-content microscopy-based assays combined with siRNA-mediated depletion of individual subunits indicated that a specific sub-complex containing VPS15, VPS34, Beclin 1, UVRAG and BIF-1 regulates both receptor degradation and cytokinesis, whereas ATG14L, a PI3K-III subunit involved in autophagy, is not required. The unanticipated role of UVRAG and BIF-1 in cytokinesis was supported by a strong localisation of these proteins to the midbody. Importantly, while the tumour suppressive functions of Beclin 1, UVRAG and BIF-1 have previously been ascribed to their roles in autophagy, these results open the possibility that they may also contribute to tumour suppression via downregulation of mitogenic signalling by growth factor receptors or preclusion of aneuploidy by ensuring faithful completion of cell division.