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At least 577 records · Page 32Linked to original sources

PubMed2001

[A clinical investigation into the effect of comfort denture adhesive on masticatory function with complete dentures].

OBJECTIVE: The purpose of this study was to evaluate the clinical effect of the new developed form of Comfort denture adhesive (Comfort DA). METHODS: 10 edentulous patients with complete dentures were selected for this study. The maximum biting force and masticatory efficiency were recorded before and after application of the adhesive to all the new and old dentures. Subjective test was also used to evaluate this adhesive in enhancing retention and stability of complete denture using the questionnaire way. RESULTS: The data indicated that significantly greater biting forces were generated with old dentures than with the new dentures. The major findings were that the adhesive produced a statistically significant improvement in the masticatory efficiency after application. Subjective views of the patients indicated that this tested product significantly improved denture retention, stability and had other favorable features. The time of adhesion was about 6 8 hours. CONCLUSION: The generally favorable clinical performance of the developed Comfort DA formulation indicated that it might be an efficacious denture adhesive.

English Abstract↗

PubMed1991

Potentiometric and electron nuclear double resonance properties of the two spin forms of the [4Fe-4S]+ cluster in the novel ferredoxin from the hyperthermophilic archaebacterium Pyrococcus furiosus.

Pyrococcus furiosus ferredoxin contains a single [4Fe-4S] that exists in both S = 1/2 (20%) and S = 3/2 (80%) ground states in the reduced protein. We report here on the temperature-dependent potentiometric properties of the two spin forms, their stability, and on the structural features that differentiate them. The midpoint potential (Em) of the cluster in either spin state was determined at -365 mV (30 degrees C, pH 8.0). By rapidly freezing samples for EPR analyses, it was shown that the Em values of both spin states appear to change by -1.7 mV/degrees C over the range 20 degrees-80 degrees C, and by -6 mV/degrees C between 80 and 89 degrees C. The Em values and the relative amounts of the S = 1/2 and S = 3/2 forms of the cluster were unaffected by pH (6.8-10.5), even at 85 degrees C, and were unchanged by the presence of NaCl (1.0 M), sodium dodecyl sulfate (10%, w/v) or ethylene glycol (50%, v/v), even at 80 degrees C. The S = 1/2 form of the [4Fe-4S]+ cluster was found to exhibit a strongly coupled 1H ENDOR resonance (A = 22 MHz) that was exchangeable with the solvent. Such a large coupling has not been observed in any other iron-sulfur protein. Since a unique feature of this 4Fe-ferredoxin is that only 3 cysteinyl residues appear to be coordinated to the [4Fe-4S] cluster, the ENDOR data are consistent with an H2O molecule being a ligand to the unique Fe site. The S = 3/2 form of the [4Fe-4S]+ cluster exhibited a similar, strongly coupled 1H ENDOR resonance, but in this spin state it was not exchangeable with the solvent. This suggests that the [4Fe-4S]+ cluster exhibiting the S = 3/2, but not the S = 1/2 ground state, is "shielded" from the solvent, presumably by neighboring amino acid residues. In view of the pH dependence of the midpoint potential of the two spin states, the fourth ligand to the cluster and the source of the strongly coupled 1H ENDOR resonance is probably an OH- rather than H2O molecule.

Archaea↗

PubMed1990

[Effect of intensification of vocational education on health status of 14-year-old students].

Intensification of the educational-industrial training of turners-to-be under the conditions of an ++inter-school educational-industrial integrated works produces a training effect on the 14-year old pupils (9-th form), evidence of which is the development of features of physiological fatigue and stabilization of adaptational processes of the cardio-vascular system. Early involvement of pupils in the productive labour facilitates activation of professionally significant physiological functions, increase in the motor activity, reduction of the level of acute morbidity with the absence of unfavourable changes in health status and physical development.

Adolescent↗

PubMed1989

Analysis of machine-selected cells with an image analysis system in normal and abnormal cervical specimens.

An analysis has been performed of visual diagnostic criteria used in cervical cytology applied to machine selected cells in relation to automated classification based on variables, which can be recorded in an image system with automated cell search and segmentation, feature extraction and classification. A 98% accuracy could be obtained with the choice of the most ideal statistical methods for discrimination and the use of the most powerful variables recorded in the image system when compared with consensus of the visual diagnoses based on established cytological criteria for diagnosis of cancer and precancer of the cervix uteri. The most powerful discriminatory variables in the image system (of 17 recorded) for discrimination between normal and abnormal epithelial cells were, in addition to nuclear extinction, cytoplasmic extinction and cytoplasmic shape. It is concluded that the visual classification of cervical cells is highly accurate with experienced observers and that imaging microscopes can be trained to nearly equal this accuracy with appropriate statistical methods of discrimination. The problem of creating fully automated systems, however, also requires the inclusion of even more effective discriminatory variables and also the solution of such problems as automatic cell search, segmentation, artifact rejection, feature extraction, classification and electronic stability in order to become cost-effective.

Cervix Uteri↗

PubMed1989

[Photo-degradation of plant-protecting agents].

The photo degradation of some agents of plant-protecting agents is illustrated by survey. The author proves that the photolytic degradation is a relevant process of the total degradation in many agents so that it has in an increasing manner to be taken into consideration with the ecologic-chemical assessment of plant-protecting agents. The photolysis of agents is discussed for the conditions in water, at surfaces of the ground, plants and glass at open grounds and models. The velocity of photolytic degradation of the agent mainly depends on the medium at or within which the agent exists. A correlation between stability of the photolysis and features of the structure of the chemical compound can be realized by means of the quantum efficiency.

Humans↗

PubMedDate not supplied

Proliferation behavior of xenografted human tumors: a flow cytometric study.

The proliferation behavior of three adenocarcinomas derived from the colon rectum, colon sigmoideum and the lung was pursued by flow cytophotometry between 0 h and 38 h after heterotransplantation to athymic mice. On principle, the same pattern of alterations was observed in the case of all three tumors, the time parameters slightly varying in dependence on growth velocity. At first, the number of intact tumor cells markedly decreased during 16-24 h after transplantation, being accompanied by an increase of cellular debris and an immigration of numerous host animal cells; the latter became the quantitatively preponderant portion of cells between days 2 and 8. On day 6, the tumor cell population began to proliferate. At first, the G1 peak rose, followed by the appearance of tumor cells in the S and (G2 + M) phases. Simulataneously, the relative portions of mouse cells and cellular debris diminished. Between days 14 and 30, when maximum rates of macroscopic growth of the heterotransplants were achieved, the cytokinetic features of the xenografts had stabilized and were characterized by the presence of a small portion of mouse cells and a prominent tumor cell population, most cells being in the G1 phase and a smaller number passing through the S and (G2 + M) phases. Beyond day 30, degeneration phenomena again occurred, which were reflected by a decay of mouse and tumor cell populations and a simultaneous increase of cell fragments. By cytokinetic means, the results of the present study reveal a multistep development of human tumors after heterotransplantation into nude mice, and confirm the importance of host-supplied cells for the removal of degenerated tumor cells and the induction of tumor cell proliferation. Moreover, the results show that a stable cytokinetic pattern is found only during the phase of macroscopic tumor growth and the following phase of steady state.

Adenocarcinoma↗

PubMed1986

Thoracolumbar fractures.

Vertebrae from the 11th thoracic to the 2nd lumbar region are particularly vulnerable to fracture. Classification is based academically on the forces involved in the fracturing mechanism, and corresponding radiological features. The determination of the stability of the fracture influences management, which involves two schools of thought: the proponents of a conservative approach and those who believe in open reduction and internal fixation. Diagnosis and management are discussed.

Bone Plates↗

PubMedDate not supplied

[Infectious bovine rhinotracheitis (VHB-1). II. Physico-chemical properties of strain L-114].

The thermal stability, density gradient and morphological features of a recently isolated L-114 strain of infectious bovine rhinotracheitis virus were determined. Morphology studies showed an enveloped virus with 200 nm of total diameter, a core diameter of 90 nm and an icosaedral-type structure; purified preparations contained both complete and empty viral particles. More than 90% of the infectivity was lost after 15 hours at 37 degrees C; at 56 degrees C, inactivation was much faster, with a 3 log titer reduction, in 24 minutes. Density gradient studies in cesium chloride, carried out with virus concentrated on sucrose gradient, gave an estimated density of 1.25 g/ml for the purified virus, which fits with light herpesviruses.

Centrifugation, Density Gradient↗

PubMed1980

Ataranalgesia - an intravenous anesthetic technique. Experience with 978 administrations.

Ataranalgesia, an intravenous anesthetic technique, based on flunitrazepam and ketamine is described. Using balanced combinations of these drugs, with and without the addition of nitrous oxide and oxygen, this technique can cover a wide spectrum of anesthetic practice including pediatric and cardiovascular surgery. Over a period of six months, ataranalgesia with spontaneous respiration was used in 88% of all medium and minor gynecological procedures performed at our hospital for a total of 1194 anesthetics. Seventy percent of these anesthetics were given to outpatients. Cardiovascular stability was the most prominent feature of the technique. Heart rate (HR) and systolic blood pressure (BP) increases were found to be inversely related to pre-operative values. Circulatory effects were not influenced by variation in premedicants.

Adolescent↗

PubMed1983

Indoramin in the treatment of hypertension. A mini-review and update.

The origins, preclinical development and clinical pharmacology of a new antihypertensive agent, indoramin (Baratol; Wyeth), are briefly reviewed. Indoramin is a competitive postsynaptic alpha-adrenoceptor antagonist with a myocardial membrane-stabilizing component of action. These features are believed to be responsible for its antihypertensive efficacy. They may also explain the absence of problems common to older alpha-blockers such as reflex tachycardia and postural hypotension. Clinical evaluation of a new agent such as indoramin in the management of hypertension is discussed in terms of efficacy, dosage regimen, tolerance, adverse effects, interactions, withdrawal syndrome, and long-term influence on the complications of high blood pressure.

Animals↗

PubMed1984

[Properties of phospholipase A2 from the venom of the large hornet Vespa orientalis].

Some properties (catalytic and hemolytic activity, pH and temperature optima, stability, substrate specificity, effects of detergents and metal ions, N-terminal sequence, chemical modification of histidine in the enzyme active center, etc.) of phospholipase A2 from hornet (Vespa orientalis) venom were studied. It was shown that phospholipase A2 from hornet venom differs essentially from other enzymes of this species in terms of stability, catalytic properties and structural features. The active center of the enzyme contains an essential histidine residue, similar to other phospholipases A2 from various sources. Unlike other known forms of phospholipase A2, the enzyme under study exerts a pronounced hemolytic action. The hemolysis is inhibited by Ca2+ at concentrations capable of inducing the activation of the hydrolytic activity of the enzyme.

Amino Acid Sequence↗

PubMed1996

Minimum four-year radiographic and clinical evaluation of results following femoral revision surgery with the S-ROM modular hip system.

Thirty-four patients were reviewed following revision modular cementless reconstruction for proximal femoral deficiency. One patient underwent a Girdlestone conversion for sepsis at 3 years postoperatively, leaving 33 patients with an average follow-up of 51 months (range 48 to 62 months). The average age at surgery was 60 years, and there were 17 right and 16 left hips. Patients were assessed clinically using the Merle d'Aubigné and Postel hip rating system. Radiographic assessment was performed on preoperative and postoperative films. Femoral assessment was performed using the Engh fixation stability score, Gruen zonal system for radiolucencies and observing for the presence or absence of osteolysis. The average pain score was 5.4/6 with 88% having slight or no pain. Only one patient (3%) had thigh pain. Radiographically, the average fixation stability score was 21.7 with features of bony ingrowth present in 97%, and one case with features of stable fibrous ingrowth. There was no evidence of osteolysis.

Adult↗

PubMed1998

Trends in cancer mortality in Argentina, 1966-91.

Trends in death certification rates for 12 major cancer sites and total cancer mortality in Argentina were analysed for the period 1966-91 on the basis of the World Health Organization database. In the late 1960s, total cancer mortality rates in Argentina (184/100,000 men, 117/100,000 women, world standard) were among the highest in the world. Over the 25-year period considered, however, cancer mortality in Argentina declined by 15% in both sexes, to reach 157/100,000 in men and 99/100,000 in women, for 1990-91. These rates were somewhat lower than those of North America and, particularly for women, relatively low on a worldwide scale. The favourable trends, observed mostly between the 1960s and the 1980s, reflect the steady decline in gastric cancer rates in both sexes, together with some decline in oesophageal, lung and other tobacco-related neoplasms, mostly in men, following some decline in tobacco consumption over the last two decades. The fall in oesophageal cancer may be related to decreased consumption of hot maté, too. Colorectal cancer rates were high in the 1960s, but declined by 17% in men and 35% in women. An approximately 50% decline was observed for skin cancer mortality, which was among the lowest in the world in the early 1990s, and some decline was observed also for leukaemias and uterine cancer, while breast and prostate neoplasms showed a general stability. The two major unfavourable features of cancer mortality in Argentina were the persistently high rates for oesophageal in men, and for uterine cancer mortality in women. These are likely a result of hot maté drinking for oesophageal cancer and inadequate screening for cervical cancer.

Age Distribution↗

PubMed1998

The unusually slow unfolding rate causes the high stability of pyrrolidone carboxyl peptidase from a hyperthermophile, Pyrococcus furiosus: equilibrium and kinetic studies of guanidine hydrochloride-induced unfolding and refolding.

To elucidate the energetic features of the anomalously high-level stabilization of a hyperthermophile pyrrolidone carboxyl peptidase (PfPCP) from a hyperthermophilic archaeon, Pyrococcus furiosus, equilibrium and kinetic studies of the guanidine hydrochloride (GuHCl)-induced unfolding and refolding were carried out with CD measurements at 220 nm in comparison with those from the mesophile homologue (BaPCP) from Bacillus amyloliquefaciens. The mutant protein of PfPCP substituted with Ser at both Cys142 and Cys188 (PfC142/188S) was used. The GuHCl unfolding for PfC142/188S and BaPCP was reversible. It was difficult to obtain the equilibrated unfolding curve of the hyperthermophile proteins at temperatures below 50 degreesC and pH 7, because of the remarkably slow rate of the unfolding. The unfolding for PfC142/188S attained equilibrium after 7 days at 60 degreesC, resulting in the coincidence between the unfolding and refolding curves. The Gibbs energy change of unfolding, DeltaGH2O (56.6 kJ/mol), for PfC142/188S at 60 degreesC and pH 7 was dramatically higher than that (7.6 kJ/mol) for BaPCP at 40 degreesC and pH 7. The unfolding and refolding kinetics for PfC142/188S and BaPCP at both 25 and 60 degreesC at pH 7 were approximated as a single exponential. The rate constant in water (kuH2O) of the unfolding reaction for PfC142/188S (1.6 x 10(-)15 s-1) at 25 degreesC and pH 7 was drastically reduced by 7 orders of magnitude compared to that (1.5 x 10(-)8 s-1) for BaPCP, whereas the refolding rates (krH2O) in water for PfC142/188S (9.3 x 10(-)2 s-1) and BaPCP (3.6 x 10(-)1 s-1) at 25 degreesC and pH 7 were similar. These results indicate that the greater stability of the hyperthermophile PCP was characterized by the drastically slow unfolding rate.

Circular Dichroism↗

PubMed1992

Coordination of expression of Zymomonas mobilis glycolytic and fermentative enzymes: a simple hypothesis based on mRNA stability.

Although Zymomonas mobilis is prototrophic, glycolytic and fermentative enzymes (ethanologenic enzymes) constitute over half of the cytoplasmic protein. In this study, transcript stability, functional message pools, and the abundance of cytoplasmic products were compared for genes encoding eight of these essential enzymes. The transcripts of all were very stable, with half-lives ranging from 8 to 18 min. This transcript stability is proposed as an important feature in Z. mobilis that may distinguish highly expressed genes for energy generation from biosynthetic genes, which are required at much lower levels. The evolution of multiple promoters to enhance transcription from single-copy genes, of structural features that alter translational efficiency, and of differences in protein turnover is hypothesized to serve a subordinate role in the regulation of Z. mobilis gene expression. Among the eight ethanologenic genes examined, differences in transcript stability were found to directly correlate with differences in functional message pools and cytoplasmic protein levels. These differences in transcript stability are hypothesized to have evolved as a primary mechanism to balance the levels of individual enzymes within the glycolytic and fermentative pathways.

Bacterial Proteins↗

PubMed1980

Towards a rationale for neural stability: a model of neural computation and network architecture.

Networks of Boolean processing cells with low connectivity are known to be inherently stable, in the sense that they exhibit only limited reverberatory activity among their possible state transitions. This paper discusses the value of such a network as a functional model of a neural system and, in the light of the observed decrease in stability with increasing cell connectivity, seeks to identify the features of network architecture and cell computation which act to protect network stability, thereby providing a framework for an understanding of neural stability.

Cell Communication↗

PubMed2006

Calorimetric study on the induction of interdigitated phase in hydrated DPPC bilayers by bioactive labdanes and correlation to their liposome stability: The role of chemical structure.

Labd-7,13-dien-15-ol (1), labd-13-ene-8alpha,15-diol (2), and labd-14-ene-8,13-diol (sclareol) have been found to exhibit cytotoxic and cytostatic effects. Their partitioning into phospholipid bilayers may induce membrane structure modifications, crucial in the development of liposomes. DSC was used to elucidate the profile of modifications induced in DPPC bilayers by incorporating increasing concentrations of the labdanes. Labdanes 1, 2 and sclareol were incorporated into SUV liposomes composed of DPPC their physicochemical stability was monitored (4 degrees C) and was compared to liposomes incorporating cholesterol. All labdanes strongly affect the bilayer organization in a concentration dependent manner in terms of a decrease of the cooperativity, the fluidization and partially destabilization of the gel phase, the induction of a lateral phase separation and the possible existence of interdigitated domains in the bilayer. The physicochemical stability of liposomes was strongly influenced by the chemical features of the labdanes. The liposomal preparations were found to retain their stability at low labdane concentration (10 mol%), while at higher concentrations up to 30 mol% a profound decrease in intact liposomes occurred, and a possible existence of interdigitated sheets was concluded.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed2000

Purification and characterization of a cold-adapted uracil-DNA glycosylase from Atlantic cod (Gadus morhua).

Uracil-DNA glycosylase (UDG; UNG) has been purified 17000-fold from Atlantic cod liver (Gadus morhua). The enzyme has an apparent molecular mass of 25 kDa, as determined by gel filtration, and an isoelectric point above 9.0. Atlantic cUNG is inhibited by the specific UNG inhibitor (Ugi) from the Bacillus subtilis bacteriophage (PBS2), and has a 2-fold higher activity for single-stranded DNA than for double-stranded DNA. cUNG has an optimum activity between pH 7.0-9.0 and 25-50 mM NaCl, and a temperature optimum of 41 degrees C. Cod UNG was compared with the recombinant human UNG (rhUNG), and was found to have slightly higher relative activity at low temperatures compared with their respective optimum temperatures. Cod UNG is also more pH- and temperature labile than rhUNG. At pH 10.0, the recombinant human UNG had 66% residual activity compared with only 0.4% for the Atlantic cUNG. At 50 degrees C, cUNG had a half-life of 0.5 min compared with 8 min for the rhUNG. These activity and stability experiments reveal cold-adapted features in cUNG.

Adaptation, Physiological↗