bluuebunny/crossref_metadata_2025 huggingface dataset:
Cold-induced heat production preceding shivering
Authors: Ooijen Anne M. J. van , Lichtenbelt Wouter D. van Marken , Steenhoven Anton A. van , Westerterp Klaas R.
Published: May 2005

Individual changes in heat production and body temperature were studied in response to cold exposure, prior to shivering. The subjects ten women (seven men) were of normal weight, had a mean age of 23 (SD 3) years and average BMI 22·2 (SD 1·6) Kg/m2. They were lying supine under thermoneutral conditions for 30 min and were subsequently exposed to air of 15°C until shivering occurred. Heat production was measured with a ventilated hood. Body composition was measured with underwater weighing and 2H dilution. Body temperatures were measured with thermistors. Heat production during cold exposure prior to shivering increased and reached a plateau. Skin temperature decreased and did not reach a plateau during the test period. The non-shivering interval (NSI) ranged from 20 to 148 min, was not related to body composition and was not significantly different between women (81 (sd 15) min) and men (84 (sd 34) min). NSI was negatively related to skin temperature (r2 0·44, P=0·004), and skin temperature was related to heat production (r2 0·39, P=0·007) In conclusion, subjects with a relatively large heat production during cold exposure maintained a relatively high skin temperature but showed a short NSI, independent of differences in body composition.
Simulation of prospective phytosterol intake in Germany by novel functional foods
Authors: Kuhlmann Karolin , Lindtner Oliver , Bauch Almut , Ritter Guido , Woerner Brigitte , Niemann Birgit
Published: May 2005

A blood cholesterol-lowering margarine containing plant sterolesters was the first functional food placed on the European food market pursuant to the regulation (EC) 258/97. In the following years nine further applicants submitted the request to add plant sterol compounds to dairy products, cheeses, bakery products, sausages, plant oils and other products. The European Scientific Committee on Food (SCF) declared a precautionary intake limit of 3 g plant sterols per d by multiple dietary sources. Using the consumption data of the German National Food Consumption Study, carried out from 1985 to 1988 with 23 209 participants, we hypothetically added 0·3–2 g plant sterols to usual daily servings of ten different food products, selected from the novel food applications. We calculated the prospective plant sterol intake regarding each kind of enriched food and by stepwise accumulation of different functional foods in three enrichment scenarios. Within our enrichment context we find a phytosterol intake satiation, if multiple plant sterol-enriched foods are eaten. An enrichment amount of 2 g plant sterols per proposed food serving size results in an intake maximum of 13 g/d.
Lignan contents of Dutch plant foods: a database including lariciresinol, pinoresinol, secoisolariciresinol and matairesinol
Authors: Milder Ivon E. J. , Arts Ilja C. W. , Putte Betty van de , Venema Dini P. , Hollman Peter C. H.
Published: May 2005

Enterolignans (enterodiol and enterolactone) can potentially reduce the risk of certain cancers and cardiovascular diseases. Enterolignans are formed by the intestinal microflora after the consumption of plant lignans. Until recently, only secoisolariciresinol and matairesinol were considered enterolignan precursors, but now several new precursors have been identified, of which lariciresinol and pinoresinol have a high degree of conversion. Quantitative data on the contents in foods of these new enterolignan precursors are not available. Thus, the aim of this study was to compile a lignan database including all four major enterolignan precursors. Liquid chromatography–tandem mass spectrometry was used to quantify lariciresinol, pinoresinol, secoisolariciresinol and matairesinol in eighty-three solid foods and twenty-six beverages commonly consumed in The Netherlands. The richest source of lignans was flaxseed (301 129 μg/100 g), which contained mainly secoisolariciresinol. Also, lignan concentrations in sesame seeds (29 331 μg/100 g, mainly pinoresinol and lariciresinol) were relatively high. For grain products, which are known to be important sources of lignan, lignan concentrations ranged from 7 to 764 μg/100 g. However, many vegetables and fruits had similar concentrations, because of the contribution of lariciresinol and pinoresinol.Brassicavegetables contained unexpectedly high levels of lignans (185–2321 μg/100 g), mainly pinoresinol and lariciresinol. Lignan levels in beverages varied from 0 (cola) to 91 μg/100 ml (red wine). Only four of the 109 foods did not contain a measurable amount of lignans, and in most cases the amount of lariciresinol and pinoresinol was larger than that of secoisolariciresinol and matairesinol. Thus, available databases largely underestimate the amount of enterolignan precursors in foods.
Elements of Mediterranean diet improve oxidative status in blood of kidney graft recipients
Authors: Stachowska Ewa , Wesołowska Teresa , Olszewska Maria , Safranow Krzysztof , Millo Barbara , Domański Leszek , Jakubowska Katarzyna , Ciechanowski Kazimierz , Chlubek Dariusz
Published: May 2005

Patients were fully informed as to the study objectives and benefits, and provided written consent prior to enrolment. The study protocol was approved by the Committee on Human Research at the Pomeranian Medical University, Szczecin, Poland. An intensification of free-radical reactions may contribute to accelerated atherosclerosis in kidney graft recipients. We examined the effect of a Mediterranean-type diet (MD) on the oxidative status of the plasma and erythrocytes of kidney graft recipients. Two patient groups were formed: a study group consuming the MD diet and a control group with a low-fat diet. C-reactive protein levels in plasma, oleic acid C18: 1n-9 and linoleic acid C18: 2n-6 concentrations in triacyloglycerols were determined. To determine the oxidative status, we measured the concentrations of α-tocopherol in plasma, the content of thiobarbituric acid-reactive species (TBARS) in plasma and erythrocytes, and the activities of superoxide dismutase, catalase and glutathione peroxidase in erythrocytes. In the MD group, the activities of erythrocyte enzymes changed significantly: those of superoxide dismutase increased (P<0.001 after 6 months), catalase decreased (P<0.001 after 6 months) and glutathione peroxidase decreased (P<0.05 after 2 months). The oleic acid content of triacylglycerols was increased (P<0.006) whereas that of linoleic acid was decreased (P<0.00005), α-tocopherol levels remaining unchanged. TBARS in plasma were decreased after 6 months of MD (P<0.05). No significant correlations were observed between TBARS, oleic acid, linoleic acid and α-tocopherol levels in plasma. MD appears to protect the erythrocytes against the action of free radicals, as reflected in the modified activities of some enzymes regulating the oxidative status of these blood cells.
Aleurone flour increases red-cell folate and lowers plasma homocyst(e)ine substantially in man
Authors: Fenech Michael , Noakes Manny , Clifton Peter , Topping David
Published: May 2005

Aleurone flour (ALF) is a rich source of natural folate (>500 μg/100 g wet weight). Our objective was to establish whether intake of ALF in man can significantly improve folate status and reduce plasma homocyst(e)ine. We performed a randomised, controlled intervention, of 16 weeks duration, in free-living healthy individuals (mean age 46–52 years). Participants were assigned to one of three groups: ALF, 175 g bread made with ALF and placebo tablet each day; PCS, 175 g bread made with pericarp seed coat (PCS) flour and placebo tablet each day (low-folate control); or FA, 175 g bread made with PCS flour and tablet containing 640 μg folic acid each day (high-folate control). The daily folate intake contributed by the bread and tablet was 233 μg in the PCS group, 615 μg in the ALF group and 819 μg in the FA group. The number of participants completing all phases of the PCS, ALF and FA interventions was twenty-five, twenty-five and eighteen, respectively. Plasma and red-cell folate increased significantly (P<0·0001) and plasma homocyst(e)ine decreased significantly (P<0·0001) in the ALF and FA groups only. Plasma folate and red-cell folate in the ALF group (mean, 95 % CI) increased from baseline values of 12·9 (9·9, 15·7) nmol/l and 509 (434, 584) nmol/l to 27·1 (22·5, 31·7) nmol/l and 768 (676, 860) nmol/l, respectively. Plasma homocyst(e)ine in the ALF group decreased from 9·1 (8·2, 10·0) μmol/l at baseline to 6·8 (6·2, 7·5) μmol/l after 16 weeks. In conclusion, moderate dietary intake of ALF can increase red-cell folate and decrease plasma homocyst(e)ine substantially.
Palliative Care Among Chumash People
Authors: Adams James D. , Garcia Cecilia
Published: May 2005

Chumash Healers used breathing therapy and counseling to keep patients involved in daily life and to avoid depression. Heat therapy, massage and pain medications were used to help with pain. Another primary function of the Healer was to help the patient sleep as normally as possible, possibly using mugwort or momoy. Nutrition was considered by Healers in treating their patients. The overall concern of the Healer was to help maintain the daily routine of village life during the normal process of the death of a village member.
Class 1 Reversibly Glycosylated Polypeptides Are Plasmodesmal-Associated Proteins Delivered to Plasmodesmata via the Golgi Apparatus
Authors: Sagi Guy , Katz Aviva , Guenoune-Gelbart Dana , Epel Bernard L.
Published: May 2005

SE-WAP41, a salt-extractable 41-kD wall-associated protein that is associated with walls of etiolated maize (Zea mays) seedlings and is recognized by an antiserum previously reported to label plasmodesmata and the Golgi, was cloned, sequenced, and found to be a class 1 reversibly glycosylated polypeptide (C1RGP). Protein gel blot analysis of cell fractions with an antiserum against recombinant SE-WAP41 showed it to be enriched in the wall fraction. RNA gel blot analysis along the mesocotyl developmental axis and during deetiolation demonstrates that high SE-WAP41 transcript levels correlate spatially and temporally with primary and secondary plasmodesmata (Pd) formation. All four of the Arabidopsis thaliana  C1RGP proteins, when fused to green fluorescent protein (GFP) and transiently expressed in tobacco (Nicotiana tabacum) epidermal cells, display fluorescence patterns indicating they are Golgi- and plasmodesmal-associated proteins. Localization to the Golgi apparatus was verified by colocalization of transiently expressed AtRGP2 fused to cyan fluorescence protein together with a known Golgi marker, Golgi Nucleotide Sugar Transporter 1 fused to yellow fluorescent protein (GONST1:YFP). In transgenic tobacco, AtRGP2:GFP fluorescence is punctate, is present only in contact walls between cells, and colocalizes with aniline blue–stained callose present around Pd. In plasmolyzed cells, AtRGP2:GFP remains wall embedded, whereas GONST1:YFP cannot be found embedded in cell walls. This result implies that the targeting to Pd is not due to a default pathway for Golgi-localized fusion proteins but is specific to C1RGPs. Treatment with the Golgi disrupting drug Brefeldin A inhibits Pd labeling by AtRGP2:GFP. Integrating these data, we conclude that C1RGPs are plasmodesmal-associated proteins delivered to plasmodesmata via the Golgi apparatus.
Localization of the Microtubule End Binding Protein EB1 Reveals Alternative Pathways of Spindle Development in Arabidopsis Suspension Cells
Authors: Chan Jordi , Calder Grant , Fox Samantha , Lloyd Clive
Published: May 2005

In a previous study on Arabidopsis thaliana suspension cells transiently infected with the microtubule end binding protein AtEB1a–green fluorescent protein (GFP), we reported that interphase microtubules grow from multiple sites dispersed over the cortex, with plus ends forming the characteristic comet-like pattern. In this study, AtEB1a-GFP was used to study the transitions of microtubule arrays throughout the division cycle of cells lacking a defined centrosome. During division, the dispersed origin of microtubules was replaced by a more focused pattern with the plus end comets growing away from sites associated with the nuclear periphery. The mitotic spindle then evolved in two quite distinct ways depending on the presence or absence of the preprophase band (PPB): the cells displaying outside-in as well as inside-out mitotic pathways. In those cells possessing a PPB, the fusion protein labeled material at the nuclear periphery that segregated into two polar caps, perpendicular to the PPB, before nuclear envelope breakdown (NEBD). These polar caps then marked the spindle poles upon NEBD. However, in the population of cells without PPBs, there was no prepolarization of material at the nuclear envelope before NEBD, and the bipolar spindle only emerged clearly after NEBD. Such cells had variable spindle orientations and enhanced phragmoplast mobility, suggesting that the PPB is involved in a polarization event that promotes early spindle pole morphogenesis and subsequent positional stability during division. Astral-like microtubules are not usually prominent in plant cells, but they are clearly seen in these Arabidopsis cells, and we hypothesize that they may be involved in orienting the division plane, particularly where the plane is not determined before division.
Hexokinase II protein content is a determinant of exercise endurance capacity in the mouse
Authors: Fueger Patrick T. , Shearer Jane , Krueger Tess M. , Posey Kelly A. , Bracy Deanna P. , Heikkinen Sami , Laakso Markku , Rottman Jeffrey N. , Wasserman David H.
Published: May 2005

Hexokinase (HK) II content is elevated in fatigue resistant muscle fibres and exercise trained muscle. The aim of this study was to determine if exercise capacity is dependent on muscle HK protein content. C57Bl/6 mice with a 50% HK knockout (HK+/−), no genetic manipulation (wild‐type, WT) and an ∼3‐fold HK overexpression (HKTg) were tested. Mice (n= 12/group) completed both a maximal oxygen consumption test and an endurance capacity test (run at ∼75%) on an enclosed treadmill equipped to measure gas exchange. Arterial and venous catheters were surgically implanted into separate groups of mice (n= 9–11/group) in order to measure an index of muscle glucose uptake (Rg) during 30 min of treadmill exercise. Maximum work rate (0.95 ± 0.05, 1.00 ± 0.04 and 1.06 ± 0.07 kg m min−1), (137 ± 3, 141 ± 4 and 141 ± 5 ml kg−1 min−1) and maximal respiratory exchange ratio (1.04 ± 0.02, 1.00 ± 0.03 and 1.04 ± 0.04) were similar in HK+/−, WT and HKTg, respectively. Exercise endurance capacity (measured as time to exhaustion) increased as HK content increased (55 ± 11, 77 ± 5 and 98 ± 9 min) and this was related to Rg measured in mice during 30 min of exercise (13 ± 2, 24 ± 5 and 42 ± 5 μmol (100 g)−1 min−1). Muscle glycogen in sedentary HK+/− mice and HK+/− mice following 30 min of exercise were significantly lower than in HKTg and WT mice. However, the net exercise‐induced muscle glycogen breakdown was equal in the three genotypes. In summary, HK protein content within the range studied (a) was not associated with a difference in the capacity to perform maximal intensity exercise, (b) was a powerful determinant of the ability to sustain moderate intensity exercise, as reducing HK content impaired endurance and increasing HK content enhanced endurance, and (c) although directly related to exercise endurance, was not a determinant of net muscle glycogen usage during exercise. In conclusion, adaptations that increase HK protein content and/or functional activity such as regular exercise contribute to increased muscular endurance.
Intestinal gluconeogenesis and glucose transport according to body fuel availability in rats
Authors: Habold Caroline , Foltzer‐Jourdainne Charlotte , Le Maho Yvon , Lignot Jean‐Hervé , Oudart Hugues
Published: May 2005

Intestinal hexose absorption and gluconeogenesis have been studied in relation to refeeding after two different fasting phases: a long period of protein sparing during which energy expenditure is derived from lipid oxidation (phase II), and a later phase characterized by a rise in plasma corticosterone triggering protein catabolism (phase III). Such a switch in body fuel uses, leading to changes in body reserves and gluconeogenic precursors, could modulate intestinal gluconeogenesis and glucose transport. The gene and protein levels, and the cellular localization of the sodium–glucose cotransporter SGLT1, and of GLUT5 and GLUT2, as well as that of the key gluconeogenic enzymes phosphoenolpyruvate carboxykinase (PEPCK) and glucose‐6‐phosphatase (Glc6Pase) were measured. PEPCK and Glc6Pase activities were also determined. In phase III fasted rats, SGLT1 was up‐regulated and intestinal glucose uptake rates were higher than in phase II fasted and fed rats. PEPCK and Glc6Pase mRNA, protein levels and activities also increased in phase III. GLUT5 and GLUT2 were down‐regulated throughout the fast, but increased after refeeding, with GLUT2 recruited to the apical membrane. The increase in SGLT1 expression during phase III may allow glucose absorption at low concentrations as soon as food is available. Furthermore, an increased epithelial permeability due to fasting may induce a paracellular movement of glucose. In the absence of intestinal GLUT2 during fasting, Glc6Pase could be involved in glucose release to the bloodstream via membrane trafficking. Finally, refeeding triggered GLUT2 and GLUT5 synthesis and apical recruitment of GLUT2, to absorb larger amounts of hexoses.
Mechanism of riboflavin uptake by cultured human retinal pigment epithelial ARPE‐19 cells: possible regulation by an intracellular Ca2+–calmodulin‐mediated pathway
Authors: Said Hamid M. , Wang Shuling , Ma Thomas Y.
Published: May 2005

In mammalian cells (including those of the ocular system), the water‐soluble vitamin B2 (riboflavin, RF) assumes an essential role in a variety of metabolic reactions and is critical for normal cellular functions, growth and development. Cells of the human retinal pigment epithelium (hRPE) play an important role in providing a sufficient supply of RF to the retina, but nothing is known about the mechanism of the vitamin uptake by these cells and its regulation. Our aim in the present study was to address this issue using the hRPE ARPE‐19 cells as the retinal epithelial model. Our results show RF uptake in the hRPE to be: (1) energy and temperature dependent and occurring without metabolic alteration in the transported substrate, (2) pH but not Na+ dependent, (3) saturable as a function of concentration with an apparent Km of 80 ± 14 nm, (4) trans‐stimulated by unlabelled RF and its structural analogue lumiflavine, (5) cis‐inhibited by the RF structural analogues lumiflavine and lumichrome but not by unrelated compounds, and (6) inhibited by the anion transport inhibitors 4,4′‐diisothiocyanatostilbene‐2,2′‐disulphonic acid (DIDS) and 4‐acetamido‐4′‐isothiocyanatostilbene‐2,2′‐disulphonic acid (SITS) as well as by the Na+–H+ exchange inhibitor amiloride and the sulfhydryl group inhibitor p‐chloromercuriphenylsulphonate (p‐CMPS). Maintaining the hRPE cells in a RF‐deficient medium led to a specific and significant up‐regulation in RF uptake which was mediated via changes in the number and affinity of the RF uptake carriers. While modulating the activities of intracellular protein kinase A (PKA)‐, protein kinase C (PKC)‐, protein tyrosine kinase (PTK)‐, and nitric oxide (NO)‐mediated pathways were found to have no role in regulating RF uptake, a role for the Ca2+–calmodulin‐mediated pathway was observed. These studies demonstrate for the first time the involvement of a specialized carrier‐mediated mechanism for RF uptake by hRPE cells and show that the process is adaptively regulated in RF deficiency, and also appears to be under the regulation of an intracellular Ca2+–calmodulin‐mediated pathway.
Enhancement of calcium‐dependent afterpotentials in oxytocin neurons of the rat supraoptic nucleus during lactation
Authors: Teruyama Ryoichi , Armstrong William E.
Published: May 2005

The firing pattern of oxytocin (OT) hormone synthesizing neurons changes dramatically immediately before each milk ejection, when a brief burst of action potentials is discharged. OT neurons possess intrinsic currents that would modulate this burst. Our previous studies showed the amplitude of the Ca2+‐dependent afterhyperpolarization (AHP) following spike trains is significantly larger during lactation. In the present study we sought to determine which component of the AHP is enhanced, and whether the enhancement could be related to changes in whole‐cell Ca2+ current or the Ca2+ transient in identified OT or vasopressin (VP) neurons during lactation. We confirmed, with whole‐cell current‐clamp recordings, our previous finding from sharp electrodes that the size of the AHP following spike trains increased in OT, but not VP neurons during lactation. We then determined that an apamin‐sensitive medium‐duration AHP (mAHP) and an apamin‐insensitive slow AHP (sAHP) were specifically increased in OT neurons. Simultaneous Ca2+ imaging revealed that the peak change in somatic [Ca2+]i was not altered in either cell type, but the slow decay of the Ca2+ transient was faster in both cell types during lactation. In voltage clamp, the whole‐cell, Ca2+ current was slightly larger during lactation in OT cells only, but current density was unchanged when corrected for somatic hypertrophy. The currents, ImAHP and IsAHP, also were increased in OT neurons only, but only the apamin‐sensitive ImAHP showed an increase in current density after adjusting for somatic hypertrophy. These findings suggest a specific modulation (e.g. increased number) of the small‐conductance Ca2+‐dependent K+ (SK) channels, or their interaction with Ca2+, underlies the increased mAHP/ImAHP during lactation. This larger mAHP may be necessary to limit the explosive bursts during milk ejection.
Gain modulation by serotonin in pyramidal neurones of the rat prefrontal cortex
Authors: Zhang Zhong‐wei , Arsenault Dany
Published: May 2005

Serotonin (5‐HT) is widely implicated in brain functions and diseases. The vertebrate brain is extensively innervated by 5‐HT fibres originating from the brain stem, and 5‐HT axon terminals interact with other neurones in complex ways. The cellular mechanisms underlying 5‐HT function in the brain are not well understood. The present study examined the effect of 5‐HT on the responsiveness of neurones in the neocortex. Using patch‐clamp recording in acute slices, we showed that 5‐HT substantially increased the slope (gain) of the firing rate‐current curve in layer 5 pyramidal neurones of the rat prefrontal cortex. The effect of 5‐HT on gain is confined to the range of firing rate (0–10 Hz) that is known to be behaviourally relevant. 5‐HT also changed current threshold for spike train generation, but this effect was inconsistent, and was independent of the effect on gain. The gain modulation by 5‐HT was mediated by 5‐HT2 receptors, and involved postsynaptic mechanisms. 5‐HT2‐mediated gain increase could not be attributed to changes in the membrane potential, the input resistance or the properties of action potentials, but was associated with a reduction of the afterhyperpolarization and an induction of the slow afterdepolarization. Blocking Ca2+ entry with Cd2+ increased the gain by itself and blocked 5‐HT2‐mediated gain increase. Buffering [Ca2+]i with 25 mm EGTA also substantially reduced 5‐HT2‐mediated gain increase. Noradrenaline, which blocked the afterhyperpolarization, also induced a moderate increase in gain. Together, our results suggest that 5‐HT may regulate the dynamics of cortical circuits through multiplicative scaling.
Hypoxic activation of arterial chemoreceptors inhibits sympathetic outflow to brown adipose tissue in rats
Authors: Madden C. J. , Morrison S. F.
Published: May 2005

In urethane–chloralose anaesthetized, neuromuscularly blocked, artificially ventilated rats, we demonstrated that activation of carotid chemoreceptors inhibits the elevated levels of brown adipose tissue (BAT) sympathetic nerve activity (SNA) evoked by hypothermia, by microinjection of prostaglandin E2 into the medial preoptic area or by disinhibition of neurones in the raphe pallidus area (RPa). Peripheral chemoreceptor stimulation with systemic administration of NaCN (50 μg in 0.1 ml) or with hypoxic ventilation (8% O2–92% N2, 30 s) completely inhibited BAT SNA. Arterial chemoreceptor‐evoked inhibition of BAT SNA was eliminated by prior bilateral transections of the carotid sinus nerves or by prior inhibition of neurones within the commissural nucleus tractus solitarii (commNTS) with glycine (40 nmol/80 nl) or with the GABAA receptor agonist muscimol (160 pmol/80 nl; 77 ± 10% attenuation), or by prior blockade of ionotropic excitatory amino acid receptors in the commNTS with kynurenate (8 nmol/80 nl; 82 ± 10% attenuation). Furthermore, activation of commNTS neurones following local microinjection of bicuculline (30 pmol/60 nl) completely inhibited the elevated level of BAT SNA resulting from disinhibition of neurones in the RPa. These results demonstrate that hypoxic stimulation of arterial chemoreceptor afferents leads to an inhibition of BAT SNA and BAT thermogenesis through an EAA‐mediated activation of second‐order, arterial chemoreceptor neurones in the commNTS. Peripheral chemoreceptor‐evoked inhibition of BAT SNA could directly contribute to (or be permissive for) the hypoxia‐evoked reductions in body temperature and oxygen consumption that serve as an adaptive response to decreased oxygen availability.
Resetting of the arterial baroreflex increases orthostatic sympathetic activation and prevents postural hypotension in rabbits
Authors: Kamiya Atsunori , Kawada Toru , Yamamoto Kenta , Michikami Daisaku , Ariumi Hideto , Uemura Kazunori , Zheng Can , Shimizu Syuji , Aiba Takeshi , Miyamoto Tadayoshi , Sugimachi Masaru , Sunagawa Kenji
Published: May 2005

Since humans are under ceaseless orthostatic stress, the mechanism to maintain arterial pressure (AP) under orthostatic stress against gravitational fluid shift is of great importance. We hypothesized that (1) orthostatic stress resets the arterial baroreflex control of sympathetic nerve activity (SNA) to a higher SNA, and (2) resetting of the arterial baroreflex contributes to preventing postural hypotension. Renal SNA and AP were recorded in eight anaesthetized, vagotomized and aortic‐denervated rabbits. Isolated intracarotid sinus pressure (CSP) was increased stepwise from 40 to 160 mmHg with increments of 20 mmHg (60 s for each CSP level) while the animal was placed supine and at 60 deg upright tilt. Upright tilt shifted the CSP–SNA relationship (the baroreflex neural arc) to a higher SNA, shifted the SNA–AP relationship (the baroreflex peripheral arc) to a lower AP, and consequently moved the operating point to marked high SNA while maintaining AP. A simulation study suggests that resetting in the neural arc would double the orthostatic activation of SNA and increase the operating AP in upright tilt by 10 mmHg, compared with the absence of resetting. In addition, upright tilt did not change the CSP–AP relationship (the baroreflex total arc). A simulation study suggests that although a downward shift of the peripheral arc could shift the total arc downward, resetting in the neural arc would compensate this fall and prevent the total arc from shifting downward to a lower AP. In conclusion, upright tilt increases SNA by resetting the baroreflex neural arc. This resetting may compensate for the reduced pressor responses to SNA in the peripheral cardiovascular system and contribute to preventing postural hypotension.
Facilitating efferent inhibition of inner hair cells in the cochlea of the neonatal rat
Authors: Goutman Juan Diego , Fuchs Paul Albert , Glowatzki Elisabeth
Published: May 2005

Cholinergic brainstem neurones make inhibitory synapses on outer hair cells (OHCs) in the mature mammalian cochlea and on inner hair cells (IHCs) prior to the onset of hearing. We used electrical stimulation in an excised organ of Corti preparation to examine evoked release of acetylcholine (ACh) onto neonatal IHCs from these efferent fibres. Whole‐cell voltage‐clamp recording revealed that low frequency (0.25–1 Hz) electrical stimulation produced evoked inhibitory postsynaptic currents (IPSCs) at a relatively high fraction of failures (65%) and with mean amplitudes of about −20 pA at −90 mV, corresponding to a quantum content of ∼1. Evoked IPSCs had biphasic waveforms at −60 mV, were blocked reversibly by α‐bungarotoxin and strychnine and are most likely mediated by the α9/α10 acetylcholine receptor, with subsequent activation of calcium‐dependent potassium (SK2) channels. Paired pulse stimulation with intervals of 10–100 ms caused facilitation of 200–300% in the mean IPSC amplitude. A train of 10 pulses with an interpulse interval of 25 ms produced increasingly larger IPSCs with maximum amplitudes greater than −100 pA due to facilitation and summation throughout the train. Repetitive efferent stimulation at 5 Hz or higher hyperpolarized IHCs by 5–10 mV and could completely prevent the generation of calcium action potentials normally evoked by depolarizing current injection.
Gating of TRP channels: a voltage connection?
Authors: Nilius Bernd , Talavera Karel , Owsianik Grzegorz , Prenen Jean , Droogmans Guy , Voets Thomas
Published: May 2005

TRP channels represent the main pathways for cation influx in non‐excitable cells. Although TRP channels were for a long time considered to be voltage independent, several TRP channels now appear to be weakly voltage dependent with an activation curve extending mainly into the non‐physiological positive voltage range. In connection with this voltage dependence, there is now abundant evidence that physical stimuli, such as temperature (TRPV1, TRPM8, TRPV3), or the binding of various ligands (TRPV1, TRPV3, TRPM8, TRPM4), shift this voltage dependence towards physiologically relevant potentials, a mechanism that may represent the main functional hallmark of these TRP channels. This review discusses some features of voltage‐dependent gating of TRPV1, TRPM4 and TRPM8. A thermodynamic principle is elaborated, which predicts that the small gating charge of TRP channels is a crucial factor for the large voltage shifts induced by various stimuli. Some structural considerations will be given indicating that, although the voltage sensor is not yet known, the C‐terminus may substantially change the voltage dependence of these channels.
A Mutation in the
TRPC6
Cation Channel Causes Familial Focal Segmental Glomerulosclerosis
Authors: Winn Michelle P. , Conlon Peter J. , Lynn Kelvin L. , Farrington Merry Kay , Creazzo Tony , Hawkins April F. , Daskalakis Nikki , Kwan Shu Ying , Ebersviller Seth , Burchette James L. , Pericak-Vance Margaret A. , Howell David N. , Vance Jeffery M. , Rosenberg Paul B.
Published: May 2005

Focal and segmental glomerulosclerosis (FSGS) is a kidney disorder of unknown etiology, and up to 20% of patients on dialysis have been diagnosed with it. Here we show that a large family with hereditary FSGS carries a missense mutation in the
TRPC6
gene on chromosome 11q, encoding the ion-channel protein transient receptor potential cation channel 6 (TRPC6). The proline-to-glutamine substitution at position 112, which occurs in a highly conserved region of the protein, enhances TRPC6-mediated calcium signals in response to agonists such as angiotensin II and appears to alter the intracellular distribution of TRPC6 protein. Previous work has emphasized the importance of cytoskeletal and structural proteins in proteinuric kidney diseases. Our findings suggest an alternative mechanism for the pathogenesis of glomerular disease.
Extension of Murine Life Span by Overexpression of Catalase Targeted to Mitochondria
Authors: Schriner Samuel E. , Linford Nancy J. , Martin George M. , Treuting Piper , Ogburn Charles E. , Emond Mary , Coskun Pinar E. , Ladiges Warren , Wolf Norman , Van Remmen Holly , Wallace Douglas C. , Rabinovitch Peter S.
Published: May 2005

To determine the role of reactive oxygen species in mammalian longevity, we generated transgenic mice that overexpress human catalase localized to the peroxisome, the nucleus, or mitochondria (MCAT). Median and maximum life spans were maximally increased (averages of 5 months and 5.5 months, respectively) in MCAT animals. Cardiac pathology and cataract development were delayed, oxidative damage was reduced, H
2
O
2
production and H
2
O
2
-induced aconitase inactivation were attenuated, and the development of mitochondrial deletions was reduced. These results support the free radical theory of aging and reinforce the importance of mitochondria as a source of these radicals.
REGULATION OF PROTEIN ACTIVITIES BY PHOSPHOINOSITIDE PHOSPHATES
Authors: Niggli Verena
Published: May 2005

Phosphoinositide phosphates (PIPs) correspond to phosphorylated derivatives of phosphatidylinositol (PI). Despite their relatively low abundance in the plasma membrane, PIPs play a crucial role as precursors of second messengers and are themselves important signaling and targeting molecules. Indeed, modulation of levels of PIPs affects, for example, cortical actin organization, membrane dynamics, and cell migration. The focus of this review is on selected interesting targets of PIPs. Those proteins that bind PIPs and are involved in regulation of actin assembly, actin membrane linkage, and actin contractility are discussed, as well as those that are involved in signaling, such as small GTPases, protein kinases, and phosphatases, or in regulation of membrane dynamics.
Glutamine inhibits cytokine-induced apoptosis in human colonic epithelial cells via the pyrimidine pathway
Authors: Evans Mary E. , Jones Dean P. , Ziegler Thomas R.
Published: May 2005

Glutamine (Gln) prevents apoptosis in intestinal epithelial cells, but the mechanism(s) remain unknown. Gln-derived metabolites include ammonia, glutamate (Glu), glutathione (GSH), and nucleotides. We previously showed that Gln potently inhibited apoptosis in cytokine-treated human colonic HT-29 cells; this effect was specific to Gln, unaffected by Glu, and unrelated to intracellular GSH. The current research examines mechanism(s) for Gln-induced antiapoptotic effects in HT-29 cells treated with TNF-α-related apoptosis-inducing ligand (TRAIL). Proliferating cells were treated with Gln or selected Gln metabolites for 24 h. Cells were then treated with TRAIL and Gln or its downstream metabolites, and apoptosis was assessed at 8 h after treatment. The purine and pyrimidine precursors inosine and orotate inhibited TRAIL-induced apoptosis. However, inhibition of purine synthesis with azaserine did not alter the potent antiapoptotic effect of Gln. In contrast, the pyrimidine synthesis inhibitor, acivicin, completely prevented this response. Supplementation with the pyrimidine uracil or the pyrimidine precursor orotate rescued the acivicin-induced blockade of Gln antiapoptotic action. Removal of bicarbonate, a substrate for pyrimidine synthesis, also inhibited the antiapoptotic effects of Gln. Uracil and thymine alone also significantly decreased TRAIL-induced apoptosis. The antiapoptotic effects of Gln were independent of DNA/RNA synthesis as measured by flow cytometry and bromodeoxyuridine incorporation. In conclusion, Gln prevents TRAIL-induced apoptosis in HT-29 cells through a mechanism involving the pyrimidine pathway. Our data also demonstrate the novel antiapoptotic effects of pyrimidine bases and their precursor orotate in these human intestinal cells.
Toll-like receptor-4 regulation of hepaticCyp3a11metabolism in a mouse model of LPS-induced CNS inflammation
Authors: Goralski Kerry B. , Abdulla Dalya , Sinal Christopher J. , Arsenault Andre , Renton Kenneth W.
Published: May 2005

Central nervous system (CNS) infection and inflammation severely reduce the capacity of cytochrome P-450 metabolism in the liver. We developed a mouse model to examine the effects of CNS inflammation on hepatic cytochrome P-450 metabolism. FVB, C57BL/6, and C3H/HeouJ mice were given Escherichia coli LPS (2.5 μg) by intracerebroventricular (ICV) injection. The CNS inflammatory response was confirmed by the elevation of TNF-α and/or IL-1β proteins in the brain. In all mouse strains, LPS produced a 60–70% loss in hepatic Cyp3a11 expression and activity compared with saline-injected controls. Adrenalectomy did not prevent the loss in Cyp3a11 expression or activity, thereby precluding the involvement of the hypothalamic-adrenal-pituitary axis. Endotoxin was detectable (1–10 ng/ml) in serum between 15 and 120 min after ICV dosing of 2.5 μg LPS. Peripheral administration of 2.5 μg LPS by intraperitoneal injection produced similar serum endotoxin levels and a similar loss (60%) in Cyp3a11 expression and activity in the liver. The loss of Cyp3a11 in response to centrally or peripherally administered LPS could not be evoked in Toll-like receptor-4 (TLR4)-mutant (C3H/HeJ) mice, indicating that TLR4 signaling pathways are directly involved in the enzyme loss. In summary, we conclude that LPS is transferred from the brain to the circulation in significant quantities in a model of CNS infection or inflammation. Subsequently, LPS that has reached the circulation stimulates a TLR4-dependent mechanism in the periphery, evoking a reduction in Cyp3a11 expression and metabolism in the liver.
Olmesartan, a novel AT1 antagonist, suppresses cytotoxic myocardial injury in autoimmune heart failure
Authors: Yuan Zuyi , Nimata Masaomi , Okabe Taka-aki , Shioji Keisuke , Hasegawa Koji , Kita Toru , Kishimoto Chiharu
Published: May 2005

Some ANG II receptor type 1 (AT1) antagonists are reported to inhibit proinflammatory cytokine production in vitro and in vivo. However, the effects of the drugs on autoimmune diseases are unknown. We tested the hypothesis that olmesartan, a novel AT1 antagonist, ameliorated experimental autoimmune myocarditis (EAM) in rats attributed to the suppression of inflammatory cytokines as well as to the immunomodulatory action of the heart. We administered olmesartan orally at does of 1, 3, and 10 mg·kg−1·day−1 to rats with EAM for 3 wk. The results showed that olmesartan decreased blood pressure significantly compared with the untreated group and markedly reduced the severity of myocarditis associated with the decrease of myocardial macrophage, CD4+, and CD8+ T-cell expression by comparison of heart wt-to-body wt ratios, pericardial effusion scores, and macroscopic and microscopic scores. Numbers of myocardial interleukin-1β (IL-1β)-positive-staining cells (obtained by immunohistochemistry) and quantities of IL-1β expression (obtained by Western blotting) were significantly lower in rats with EAM given olmesartan treatment compared with rats given vehicle. Cardiac myosin-specific, delayed-type hypersensitivity was significantly lower in olmesartan-treated rats than in control rats. The cytotoxic activities of lymphocytes in rats with EAM treated with olmesartan were reduced compared with untreated control rats. In vitro study showed that both olmesartan and its active metabolite RNH-6270 suppressed IL-1β production in U-937 cells and cultured myocytes. Olmesartan ameliorates acute EAM in rats. The cardioprotection of olmesartan may be due to suppression of inflammatory cytokines as well as to suppressive effects of cytotoxic myocardial injury in addition to hemodynamic modifications.
Effects of cytokine treatment on angiotensin II type 1A receptor transcription and splicing in rat cardiac fibroblasts
Authors: Cowling Randy T. , Zhang Xiaowei , Reese Vanessa C. , Iwata Michikado , Gurantz Devorah , Dillmann Wolfgang H. , Greenberg Barry H.
Published: May 2005

Angiotensin II (ANG II) plays important roles in cardiac extracellular matrix remodeling via its type 1A (AT1A) receptor. The cytokines tumor necrosis factor-α and interleukin-1β (IL-1β) were shown previously to upregulate AT1Areceptor mRNA and protein, thereby increasing the profibrotic response to ANG II in cardiac fibroblasts. The present experiments implicate increased nuclear factor-κB (NF-κB)-dependent transcription and also, to a lesser extent, altered mRNA splicing in the mechanism of receptor upregulation. Cytokine stimulation was found to increase AT1Aheterogeneous nuclear RNA levels, which strongly suggests that mRNA upregulation occurs transcriptionally. The transcription factor NF-κB was previously deemed necessary for cytokine-induced AT1Areceptor mRNA upregulation. Computer analysis of upstream DNA sequences revealed putative NF-κB elements at −365 and −2540 bp. Both isolated elements were shown to bind NF-κB (using gel-shift assays) and to transactivate a minimal promoter (using reporter assays), although the element at −365 bp appeared stronger. Three splice variants of AT1Areceptor mRNA that have different 5′ untranslated regions were detected in rat tissues, namely, exons 1-2-3 (predominant), 1-2-3+6, and 1-3. Cytokine treatment of fibroblasts upregulated all splice variants, but exon 1-3 increased more than the others. This differential upregulation, albeit of modest magnitude, was statistically significant with IL-1β treatment. Exon 2 contains an inhibitory minicistron and a predicted inhibitory hairpin structure. Luciferase reporter assays indicated that each splice variant translates at a different efficiency, with exon 1-2-3+6 (both minicistron and hairpin) < exon 1-2-3 (minicistron only) < exon 1-3 (neither minicistron or hairpin). These results provide evidence that cytokines increase AT1protein levels by altering both transcription and splicing.
Transmural sheet strains in the lateral wall of the ovine left ventricle
Authors: Cheng Allen , Langer Frank , Rodriguez Filiberto , Criscione John C. , Daughters George T. , Miller D. Craig , Ingels Neil B.
Published: May 2005

In an attempt to provide a better understanding of our finding that regions with contracting left ventricular myofibers need not develop a significant transmural systolic wall thickening gradient, the analytic approach of Costa et al. ( Am J Physiol Heart Circ Physiol 276: H595–H607, 1999) was applied to the four-dimensional dynamic data obtained 1 and 8 wk after surgical implantation of transmural radiopaque beads in the lateral equatorial left ventricular wall in seven ovine hearts. Quantitative histology of tissue blocks demonstrated that fiber angles varied linearly across the wall in this region from −37° in the subepicardium to +18° in the subendocardium. Sheet angles exhibited a pleated-sheet behavior, alternating sign from subepicardium to subendocardium. From end diastole (reference configuration) to end systole (deformed configuration), fiber strain was uniformly negative, sheet extension and sheet thickening were uniformly positive, and sheet-normal shear contributed to wall thickening at all wall depths. Subepicardial radial wall thickening increased significantly from week 1 to week 8, with significant increases in the contributions from subepicardial sheet extension and sheet-normal shear. At 1 and 8 wk, the contribution of sheet-normal shear to wall thickening was substantial at all transmural depths; the contribution of sheet extension to wall thickening was greatest in the subepicardium and least in the subendocardium, and the contribution of sheet thickening to wall thickening was greatest in the subendocardium and least in the subepicardium. A mechanistic model is proposed that provides a working hypothesis that a selective decrease in subepicardial intercellular matrix stiffness is responsible for elimination of the transmural wall thickening gradient 1–8 wk after marker implantation surgery.
Acute exercise increases the ventricular arrhythmia threshold via the intrinsic adenosine receptor system in conscious hypertensive rats
Authors: Collins Heidi L. , DiCarlo Stephen E.
Published: May 2005

Coronary artery occlusion-induced tachyarrhythmias that culminate in ventricular fibrillation are the leading cause of death in developed countries. The intrinsic adenosine receptor system protects the heart from an ischemic insult. Thus the increased functional demands made on the heart during exercise may produce protective adaptations mediated by endogenous adenosine. Therefore, we tested the hypothesis that a single bout of dynamic exercise increases the ventricular arrhythmia threshold (VAT) induced by coronary artery occlusion in conscious hypertensive rats via the intrinsic adenosine receptor system. To test this hypothesis, we recorded the VAT before and on an alternate day after a single bout of dynamic treadmill exercise (12 m/min, 10% grade for 40 min). A single bout of dynamic exercise significantly reduced postexercise arterial pressure (Δ−24 ± 4 mmHg) and increased VAT (Δ+1.95 ± 0.31 min). Adenosine receptor blockade with the nonselective adenosine receptor antagonists theophylline or aminophylline (10 mg/kg) attenuated the cardioprotective effects of a single bout of dynamic exercise. Results suggest that strategies that increase myocardial ATP requirements leading to adenosine production provide protection against coronary artery occlusion.
Endothelial microparticles affect angiogenesis in vitro: role of oxidative stress
Authors: Mezentsev Alexandre , Merks Roeland M. H. , O'Riordan Edmond , Chen Jun , Mendelev Natalia , Goligorsky Michael S. , Brodsky Sergey V.
Published: May 2005

Endothelium-derived microparticles have recently been described as a new marker of endothelial cell dysfunction. Increased levels of circulating microparticles have been documented in inflammatory disorders, diabetes mellitus, and many cardiovascular diseases. Perturbations of angiogenesis play an important role in the pathogenesis of these disorders. We demonstrated previously that isolated endothelial microparticles (EMPs) impair endothelial function in vitro, diminishing acetylcholine-induced vasorelaxation and nitric oxide production by rat aortic rings and simultaneously increasing superoxide production. Herein, using the Matrigel assay of angiogenesis in vitro and a topological analysis of the capillary-like network by human umbilical vein endothelial cells (HUVECs), we investigated the effects of EMPs on formation of the vascular network. All parameters of angiogenesis were affected by treatment for 48 h with isolated EMPs in a concentration of 105 but not 103 or 104 EMPs/ml. The effects included decreases in total capillary length (24%), number of meshes (45%), and branching points (36%) and an increase in mesh area (38%). The positional and topological order indicated that EMPs affect angiogenic parameters uniformly over the capillary network. Treatment with the cell-permeable SOD mimetic Mn(III)tetrakis(4-benzoic acid) porphyrin chloride (Mn-TBAP) partially or completely restored all parameters of angiogenesis affected by EMPs. EMPs reduced cell proliferation rate and increased apoptosis rate in time- and dose-dependent manners, and this phenomenon was also prevented by Mn-TBAP treatment. Our data demonstrate that EMPs have considerable impact on angiogenesis in vitro and may be an important contributor to the pathogenesis of diseases that are accompanied by impaired angiogenesis.