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At least 379 records · Page 21Linked to original sources
PubMed2004

Characterization of the aroma of a wine from maccabeo. Key role played by compounds with low odor activity values.

An extract from a dry young wine from Maccabeo was studied by aroma extract dilution analysis (AEDA), quantitative gas chromatography, and different sensory studies. In a first study, 53 different aroma compounds were quantified and used to prepare aroma models. 2-Methyl-3-furanthiol (FD = 16) and 4-methyl-4-mercaptopentan-2-one (FD = 2), could not be quantified and were not included in those models, which were not very similar to the original wine. Omission tests did not show the existence of impact compounds. In another set of experiments, selected aroma chemicals were added to the original wine, but in only in two cases (isoamyl acetate and gamma-nonalactone) was a positive effect noted, on banana and citric notes, respectively. After these discouraging results, 4-methyl-4-mercaptopentan-2-one and 2-methyl-3-furanthiol were quantified and included in the models. The concentration of the former was as low as 5 ng x L(-)(1) (odor threshold = 0.8 ng x L(-)(1)); however, its inclusion in the synthetic mixture had a significant effect, making it very close to the original wine. Its role was confirmed by omission tests. Results are briefly discussed.

Adult↗
PubMed1982

The role played by hormonal factors in the rapid activation of liver glycogen phosphorylase in traumatized rats.

In adult male SPF rats anaesthetized with pentobarbital and subjected to traumatization in revolving Noble-Collip drums for 2 min (= 120 revolutions) maximal increases of liver glycogen phosphorylase activity were observed. In experiments on rats with permanent arterial catheters for blood sampling no posttraumatic increase of plasma norepinephrine and an only slight increase of plasma epinephrine was observed if the animals were traumatized under anaesthesia, in contrast to the considerable increases in the plasma level of both hormones in rats subjected to the injury without anaesthesia. Time and extent of the phosphorylase response of anaesthetized rats after trauma were compared with changes in enzyme activity after i.v. administration of exogenous epinephrine or glucagon. A nearly maximal response after 1 microgram kg-1 epinephrine was present within 1 min, whereas after 0.1 micrograms kg-1 of glucagon there was comparable phosphorylase activation 2 min after administration of the hormone. The plasma renin-angiotensin activity was not increased after injury for 2 min under anaesthesia so that only the increase in plasma vasopressin fitted in with the criteria for possible activators of phosphorylase. An additional role of glucagon also cannot be excluded on the basis of data obtained by the present authors. The increase of phosphorylase activity in this type of stress is ensured by several mechanisms. Moreover, the high effectivity of these hormonal factors in evoking the phosphorylase response even without major activation of the sympathicoadrenal system is underlined.

Anesthesia↗
PubMed1994

Plasma antiproteinase screen and neutrophil-mediated platelet activation. A major role played by alpha 1 antitrypsin.

Upon activation, human polymorphonuclear neutrophils (PMN) release two serine proteinases, cathepsin G (Cat.G) and elastase (HLE), which in turn synergize to activate nearby platelets. We looked for the inhibitory effect of plasma and the involvement of alpha 1 antichymotrypsin (alpha 1 ACT) and alpha 1 antitrypsin (alpha 1 AT), on this cell-to-cell cooperation. It was observed that inhibition by plasma of PMN-mediated platelet activation was rather correlated with an effect on HLE (r = 0.95) than on Cat.G (r = 0.65) enzymatic activity. Purified alpha 1 AT suppressed in a concentration-dependent manner HLE activity present in the supernatant of activated PMN. When HLE was fully blocked, alpha 1 AT started to inhibit Cat.G activity. By contrast and as expected, purified alpha 1 ACT inhibited only Cat.G activity. Using specific blocking polyclonal antibodies against alpha 1 AT and alpha 1 ACT, it was demonstrated that the inhibitory effect of plasma vs. HLE was entirely mediated by alpha 1 AT. By contrast, blockade of Cat.G activity was only partly due to plasma alpha 1 ACT and around 50% was attributable to alpha 1 AT. When plasma from patients with an acute inflammatory state was used in place of plasma from normal subjects, the inhibitory effect was more pronounced, while plasma depleted in alpha 1 AT and alpha 1 ACT was less effective. These data indicate a predominant role of alpha 1 AT in the inhibition by plasma of the PMN-mediated platelet activation.

Amino Acid Sequence↗
PubMed2001

New insights in the regulation of leukocytosis and the role played by leukocytes in septic shock.

Leukocytosis is the result of white blood cell production in the bone marrow, margination onto the blood and lymph vessels and elimination of leukocytes in the peripheral tissues and the spleen. The regulation of the exit of leukocytes from the circulation at peripheral inflammatory sites is well known as the four-step paradigm of rolling, adhesion, diapedesis and chemotaxis. The entry of white blood cells into the circulation is less well studied. In the bone marrow, immature myeloid cells adhere to the stromal network by means of interactions between oligosaccharides and lectins and between adhesion molecules. During the maturation process, cell surface molecules are altered and the possibilities for multivalent binding to stroma components or cells are gradually lost. Mature cells produce matrix metalloproteinases (MMPs) that solubilise the basement membranes of the bone marrow sinuses. Hematogenic signals of inflammation activate mature granulocytes in the bone marrow and cause an increase in the circulating pool of leukocytes. The so-called shift-to-the-left, i.e. the presence of precursor forms of differentiating neutrophils, appears during full blown reactions. In the latter situation, immature cells, positive for the CD34 cell surface marker, enter the circulation. The activities of gelatinase B and integrin interactions are indispensable to induce leukocytosis and stem cell mobilization. Indeed, with the use of neutralizing antibodies against gelatinase B and against lymphocyte-associated functional antigen-1 (LFA-1), experimentally induced leukocytosis and stem cell mobilization were blocked. What is the role of adhesion molecules and proteases in septic shock syndromes? In the early phase of endotoxinaemia or bacteraemia, the bone marrow will be activated, which leads to leukocytosis. Neutrophils secrete considerable amounts of latent MMPs, including neutrophil procollagenase (MMP-8) and progelatinase B (MMP-9). In addition, these granulocytes activate the enzymes chemically and these cells are not able to produce tissue inhibitors of metalloproteinases (TIMPs). As a result, an intensive degradation of endothelial basement membranes occurs and results in vascular leakage and shock. These observations raise the hope that inhibition of proteases might constitute a new strategy for the treatment of septic shock.

Cell Adhesion↗
PubMed2001

The modulatory role played by TNF-alpha and IL-1 beta in the inflammatory responses induced by carrageenan in the mouse model of pleurisy.

We describe here the modulation caused by intrapleural (i.pl.) injection of the cytokines TNF-alpha and IL-1beta and their specific antibodies in the early (4 h) and late (48 h) inflammatory responses caused by injection of carrageenan (Cg) into the mouse pleural cavity. The antibodies against TNF-alpha and IL-1beta, when injected 30 min prior to Cg, reduced, in a graded and significant manner, both exudation and cell migration in the early (4 h) phase, while they potentiated or had no effect in the late (48 h) phase of Cg response. The natural IL-1 receptor antagonist IL-1RA, given 30 min prior to Cg, reduced the exudation by about 50% and abolished the total and differential cell migration in the early (4 h) and late (48 h) phases of the Cg responses. The i.pl. injection of TNF-alpha or IL-1beta, 5 min prior to Cg, caused graded increase in the exudation of the early (4 h) and late (48 h) phases of the Cg-induced inflammatory responses. In contrast, these treatments markedly reduced the total and differential cell migration at 4 h, while having little or no effect on the late (48 h) phase of the Cg pleurisy. These findings extend previous results and demonstrate that the pro-inflammatory cytokines TNF-alpha and IL-1beta have a critical role in controlling both cell migration and exudation caused by injection of Cg in the mouse pleural cavity. Together, these findings may be relevant to the understanding of the mechanisms involved in airway inflammatory responses.

Animals↗
PubMed2006

Key role played by RhoA in the balance between planar and apico-basal cell divisions in the chick neuroepithelium.

The cell division axis determines the position of daughter cells and is therefore critical for cell fate. During vertebrate neurogenesis, most cell divisions take place within the plane of the neuroepithelium (Das, T., Payer, B., Cayouette, M., and Harris, W.A. (2003). In vivo time-lapse imaging of cell divisions during neurogenesis in the developing zebrafish retina. Neuron 37, 597-609. Haydar, T.F., Ang, E., Jr., and Rakic, P. (2003). Mitotic spindle rotation and mode of cell division in the developing telencephalon. Proc Natl Acad Sci U S A 100, 2890-5. Kosodo, Y., Roper, K., Haubensak, W., Marzesco, A. M., Corbeil, D., and Huttner, W. B. (2004). Asymmetric distribution of the apical plasma membrane during neurogenic divisions of mammalian neuroepithelial cells. EMBO J. 23, 2314-24). The cellular constraints responsible for this preferential orientation are poorly understood. Combining electroporation and time-lapse confocal imaging of chick neural progenitors, the events responsible for positioning the mitotic spindle and their dependence on RhoA were investigated. The results indicate that the spindle forms with a random orientation. However, the final orientation of cell divisions is dependent on two main factors: (i) an early rotation of the spindle that aligns it within the plane of the neuroepithelium, and (ii) a specific limitation of spindle oscillations, despite free rotation around the apico-basal axis. Expressing a dominant-negative RhoA leads to apico-basal cell divisions after a correct initial rotation of the spindle. Our data reveal a specific role for RhoA in the maintenance of spindle orientation, prior to anaphase. Thus, RhoA could be a key player potentially regulated by the neurogenic program or by the neural stem cell environment to control the balance between planar and apico-basal divisions, during normal or pathological development.

Animals↗
PubMed1979

Effect of leukocyte hydrolases on bacteria. XIII. Role played by leukocyte extracts, lysolecithin, phospholipase a2, lysozyme, cationic proteins, and detergents in the solubilization of lipids from Staphylococcus aureus and group A streptococci: relation to bactericidal and bacteriolytic reactions in inflammatory sites.

The bactericidal and bacteriolytic effects of lysolecithin (LL) and egg-white lysozyme (LYZ) on Staph. aureus and group A streptococci and the solubilization of phospholipids from the bacterial membranes by these agents was studied. Low concentrations of lysolecithin (1--10 microgrames/ml) are highly bactericidal for Steph. aureus and group A streptococci, but induce neither bacteriolysis nor solubilization of a substantial amount of membrane phospholipids. On the other hand, while LL at greater than 50 micrograms/ml causes substantial lipid release, a combination of LL and LYZ is absolutely needed to solubilize lipids from streptococci. This combination is, however, not bacteriolytic for this microrganism. The solubilization of lipids from staphylococci by LL is much faster than that induced in streptococci by LL + LYZ. The solubilization of the bulk of membrane lipids from staphylococci can also be achieved by Triton X-100 and by sodium lauryl sulfate and from group A streptococci by Triton X-100 plus LYZ. A variety of other detergents (e.g., Cetavlon, sodium taurocholate, cetyl pyrdinium chloride) have no lipid-releasing properties even in the presence of LYZ. The release of lipids by LYZ (in the presence of LL) from group A streptococci is related to its enzymatic activity, on a still unknown substrate, but not to its cationic nature as this muramidase cannot be replaced by a variety of cation substances (histone, polylysin, leukocyte cationic proteins, polymyxin B, and spermidine). The release of lipids from staphylococci by LL is not inhibited by a variety of anionic and cationic polyelectrocytes (heparin, liquoid, chondroitin sulfate, DNA histone, and polylysine) which markedly inhibit the release of lipids from group A streptococci by LL and LYZ. Streptococci that had been cultivated in the presence of subinhibitory concentrations of penicillin G lose their membrane phospholipids to a larger extent and by much smaller concentrations of LL and LYZ, as compared to controls, suggesting that the interference with the synthesis of the peptidoglycan increases the accessibility of the cell membrane to the lipid-releasing agents. The mechanism by which LL collaborates with LYZ in lipid release is still not known. The possible role of bacterial lipids and lyso compounds in the control of bacterial survival in inflammatory sites is briefly discussed.

Cell Membrane↗
PubMed1998

[Gynecologic examination, a role-playing for two].

Although pelvic examination (PE) is a common procedure in gynaecological practice, there is little discussion among gynaecologists about the decision-making process and the possible indications and contraindications. Moreover, examiners need to be aware that their approach and body language during PE will inevitably reflect their attitude toward women. At PE, there is tacit agreement between the examiner and the patient involving a cognitive restructuring of the situation. However, if memories of earlier experiences bearing some resemblance to the PE situation are aroused in the patient, and the emotions connected with them reactivated, she may become overwhelmed by the intensive reactions triggered. In such cases, the examiner needs to be able to recognise what is happening and provide the support the patient needs. Other responsibilities of the examiner at PE include recognising symptoms of post-traumatic stress reactions and vaginismus. In performing a young woman's first PE, the examiner's primary aim should be provide the experience; that PE is a benign procedure, unconnected with pain or distress; as the patient's experience at her first PE will inevitably influence all future examinations. Learning to perform a PE in such a way that it is beneficial to the patient in all these respects is an intricate and challenging task. However, experience with students and gynaecological teaching associates suggests that such skills can be taught and learned. The PE situation is charged with latent salubrious potential, which is usually insufficiently exploited.

Attitude of Health Personnel↗
PubMed1998

Effects of differentiation on the transcriptional regulation of the FGF-4 gene: critical roles played by a distal enhancer.

Embryonal carcinoma (EC) cells are used widely as a model system for studying the expression of developmentally regulated genes, in particular genes that are regulated at the transcriptional level when EC cells differentiate. This review focuses on the molecular mechanisms that govern the transcription of the fibroblast growth factor-4 (FGF-4) gene, which appears to be the first FGF expressed during mammalian development. Interest in this gene has increased considerably with the finding that FGF-4 is essential for mammalian embryogenesis. The FGF-4 gene has also generated considerable interest because it is inhibited at the transcriptional level when EC cells undergo differentiation and because this gene is regulated by a powerful distal enhancer located 3 kb downstream of the transcription start site in the last exon of the gene. Hence, study of the FGF-4 gene is likely to shed light on the molecular mechanisms by which distal enhancers regulate gene expression. In addition to being regulated by the downstream enhancer, the expression of this gene is influenced by a regulatory region located just upstream of the transcription start site, which contains two Sp1 motifs and a CCAAT box motif. Examination of the downstream enhancer has identified three functional cis-regulatory elements: a high mobility group (HMG) protein binding motif, an octamer binding motif, and an Sp1 motif, which are likely to bind Sox-2, Oct-3, and Sp1/Sp3, respectively, in vivo. Interestingly, Sox-2 and Oct-3 expression, like FGF-4 expression, decreases when EC cells differentiate, which suggests that the loss of these transcription factors is responsible, at least in part, for the transcriptional turn-off of the FGF-4 gene. In view of these and other findings, we present a model for the differential expression of the FGF-4 gene that includes not only the contributions of specific transcription factors, but also the contribution of chromatin structure before and after differentiation.

Animals↗
PubMed1975

A preliminary investigation into the roles played by the rectal gland and kidneys in the osmoregulation of the striped dogfish Poroderma africanum.

Presented here are the results of a preliminary investigation into ionic and osmotic regulation by the kidneys and rectal gland of the striped dogfish, Poroderma africanum. Fish with ligated rectal glands showed an increase in blood concentration of sodium and chloride within a short time period, reaching a maximum after four days. The blood concentration of the two ions then decreased over the following ten days. Control animals showed relatively unchanged blood-sodium and chloride levels, over the entire 14-day period. After salt loading, both control animals and those with ligated rectal glands showed initial rise in blood sodium and chloride levels, but these returned towards initial values within seven hours of injection. Comparison of the two groups indicates that the rectal gland may control blood-chloride levels more so than -sodium, although its action as a salt regulator does not seem very pronounced in either case. Urine and rectal gland fluid, were collected as a compound fluid, from normal fish, and the estimated cloacal salt loss is discussed. Urine from normal fish was also collected separately and was analysed for its contribution to salt loss. Results are discussed and compared with previous relevant findings.

Animals↗
PubMed1987

A stage-dependent effect of ethanol on 9.5-day rat embryos grown in culture and the role played by the concomitant rise in osmolality.

The effects of ethanol on the rat embryo undergoing organogenesis in vitro have been studied. We have shown that embryopathy is dependent on the stage of development at which explanted embryos were treated. The early neural plate (presomite) stage was highly sensitive to a 4-hour exposure of 300 mg/% ethanol, whereas embryos explanted 5 hours later, at the late head-fold (two to six somites) stage grew normally under the same conditions. We have also established that raised serum osmolality, associated with ethanol in serum, is responsible for some but not all of the teratogenic effect. This was shown by mimicking the rise in osmolality with hyperosmotic serum, containing glycerol, NaCl, or concentrated Hanks' salts. Dilution of this osmotic effect by the addition of distilled water in part reversed these embryopathic effects.

Abnormalities, Drug-Induced↗
PubMed2003

Tumouricidal activity of gilthead seabream (Sparus aurata L.) natural cytotoxic cells: the role played in vitro and in vivo by retinol acetate.

The natural cytotoxic activity of gilthead seabream head-kidney leucocytes was evaluated after in vitro incubation with retinol acetate as vitamin A source, and in samples taken from specimens receiving an intraperitoneal injection or a diet supplemented with this vitamin. Isolated leucocytes were incubated with 0 to 10(-10)m all-trans-retinol acetate-supplemented culture medium for 0, 6 or 24h and assayed for their tumouricidal activity which was found to increase for all the assayed concentrations and incubation times. Seabream specimens were intraperitoneally injected with 0 (control), 1.75 or 5.25 micro g retinol acetate 100 g(-1) biomass and sampled 1, 3 or 5 days post-injection. Leucocyte natural cytotoxic activity increased in a dose-dependent manner 1 and 3 days post-injection. When fish were fed a commercial diet supplemented with 0 (control), 50, 150 or 300 mg retinol acetate kg(-1) diet for 1, 2, 4 or 6 weeks, only fish which had been fed the highest supplement for 2 weeks showed any increase in head-kidney leucocyte cytotoxic activity. Serum was isolated and analysed for all-trans-retinol concentration by reverse-phase high-pressure-liquid-chromatography. The normal level was about 0.4 micro g ml(-1) serum, while treatment for 1 to 4 weeks with vitamin A increased this level. In conclusion, retinol acetate increases gilthead seabream head-kidney leucocyte cytotoxic activity both in vitro and in vivo.

Adjuvants, Immunologic↗
PubMed1997

Initiation of SV40 DNA replication in vitro: analysis of the role played by sequences flanking the core origin on initial synthesis events.

Replication initiation events are suppressed over the SV40 core origin in vitro; they are also greatly reduced over sequences flanking the origin which contain binding sites for several transcription factors. To address the biochemical basis for the gap in initiation events over the flanking sequences, initial synthesis events have been characterized on templates lacking these sequences. Herein, it is demonstrated that previously functional initiation sites are nearly inactive when moved to positions that are proximal to the core origin. Thus, the gap in initiation events depends, in part, on the proximity of the initiation sites to the SV40 core origin. Additional experiments demonstrate that removal of the flanking sequences had little or no effect on DNA unwinding or on the efficiency of initiation of DNA synthesis in vitro. These results indicate that, under our in vitro conditions, initiation of SV40 DNA synthesis is not enhanced by binding of transcription factors to the flanking sequences.

Antigens, Viral, Tumor↗