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At least 883 records · Page 49Linked to original sources
PubMed2005

Real-time measurements of membrane surface dynamics on macrophages and the phagocytosis of Leishmania parasites.

Defocusing microscopy was used for real-time observation and quantification of membrane surface dynamics in murine bone marrow macrophages. Small random membrane fluctuations (SRMF), possibly metabolic driven, were detected uniformly over all membrane surface. Morphological and dynamical parameters of ruffles, such as shape, dimensions, and velocity of propagation, were analyzed. Optical tweezers were used to promote phagocytosis of single Leishmania amazonensis amastigotes by selected macrophages. Analysis of ruffling activity on the macrophages before and during phagocytosis of the parasites indicated that increased ruffling response near forming phagosomes, most likely induced by the parasite, accelerates phagocytosis. The effects of temperature decrease on the dynamics of membrane surface fluctuations and on the phagocytosis of parasites were used to determine the overall activation energies involved in these processes. The values obtained support the existence of strong correlation between membrane motility and phagocytic capacity.

Animals↗
PubMed2005

High docosahexaenoic acid levels in both neutral and polar lipids of a highly migratory fish: Thunnus tonggol (Bleeker).

The lipid and FA compositions of various organs (light muscle, dark muscle, liver, pyloric cecum, and the orbital region) and of the stomach contents of a highly migratory fish species Thunnus tonggol (Bleeker) were analyzed. TAG and phospholipids (PE and PC) were the major lipid classes in the total lipids of T. tonggol. DHA was characteristically the major FA of all the major classes of all its organs except for only one case of liver TAG. The mean DHA contents of the various organs accounted for more than 20% of the total FA (TFA), even though it is a neutral depot lipid. However, DHA in the stomach contents, originating from their prey, fluctuated and was generally low. DHA levels were generally higher in a year (2000) when water temperatures were colder than in one when it was warmer (1998). Furthermore, DHA levels in muscle TAG were consistently high in spite of the fluctuation of those in the visceral TAG, which might be directly influenced by the prey lipids. This phenomenon suggests the physiological selective accumulation of DHA in the muscle, after the migration of the digested FA in the vascular system and absorption of the prey lipids in the intestine. In contrast, the FA composition of other species is generally variable and their DHA contents of TAG are usually less than 20% of TFA.

Animal Migration↗
PubMed2003

Mechanism for electron transfer within and between proteins.

Examination of a growing range of electron transfer proteins is clarifying what design elements are and are not naturally selected. Intraprotein electron transfer between natural redox centers is generally engineered to be robust and resistant to mutational changes and thermal fluctuations, by using chains of redox centers connected by electron tunneling distances of 14 A or less. This assures that tunneling rates are faster than the typical millisecond bond-breaking at catalytic sites. Interprotein electron transfer addresses the potential problem of slow diffusion by designing attractive docking sites that permit a conformational search for short tunneling distances.

Animals↗
PubMed2004

Evaluation of levo-alpha-acetylmethdol (LAAM) as an alternative treatment for methadone maintenance patients who regularly experience withdrawal: a pharmacokinetic and pharmacodynamic analysis.

The aim of this study was to determine if substitution of daily methadone with second daily levo-alpha-acetylmethadol (LAAM) would convert non-holders on methadone into holders on LAAM, and to compare plasma concentration-time profiles of (R)-methadone with LAAM and its two metabolites. Sixteen stable methadone maintenance treatment participants (non-holders, n = 8) were randomly allocated to continue methadone for 3 months or switch to LAAM for 3 months, and then crossed over to the alternative drug for 3 months. At steady state, there were two testing sessions (24 h for methadone and 48 h for LAAM), during which opioid withdrawal severity, respiration rate and pupil diameter were measured 10-11 times and venous blood was collected 13-15 times. Ten age- and gender-matched controls underwent one 48-h test session. Areas under the withdrawal severity score versus time curve (AUC(0-47) hours for LAAM and controls; AUC(0-24) x 2 for methadone) were similar in holders on methadone and LAAM (P = 0.62), but were greater in non-holders when they were taking methadone than LAAM (P < 0.001). Respiratory depression and pupillary constriction were similar for LAAM and methadone. In comparison to (R)-methadone, plasma nor- and dinor-LAAM concentrations fluctuated little over the dosing interval. LAAM converted methadone non-holders into LAAM holders. LAAM may therefore be useful in selected MMT non-holders and improve retention in opioid treatment programs.

Adult↗
PubMed2002

Evidence for a tonic GABA-ergic inhibition of excitatory respiratory-related afferents to presympathetic neurons in the rostral ventrolateral medulla.

The effect of blockade of ionotropic GABA and glutamate receptors in the rostral ventrolateral medulla (RVLM) on the relationship between phrenic nerve, splanchnic sympathetic nerve and lumbar sympathetic nerve activities was examined in urethane anesthetized, paralyzed and vagotomized Sprague-Dawley rats. Bilateral microinjection of the GABA-A receptor antagonist, bicuculline (4 mM, 100 nl), into the RVLM dramatically, and almost exclusively, increased the post-inspiratory related discharge in both splanchnic sympathetic nerve and lumbar sympathetic nerve activities and elicited hypertension with fluctuations of arterial pressure phase locked to the discharge of the phrenic nerve. Subsequent bilateral microinjection of kynurenate, a non-selective ionotropic excitatory amino acid receptor antagonist (50 mM, 100 nl), into the RVLM significantly attenuated the sympathoexcitation and hypertension evoked by injection of bicuculline. This was accompanied by an abolition of the post-inspiratory related burst discharge of splanchnic sympathetic nerve and lumbar sympathetic nerve activities. These data suggest that the GABAergic inputs to RVLM tonically inhibit glutamatergic inputs from central respiratory neurons that normally act to increase the firing of presympathetic neurons in the RVLM. Inputs from post-inspiratory neurons appear to be an especially potent excitatory synaptic drive to the presympathetic neurons in the absence of the GABAergic inhibition.

Action Potentials↗
PubMed1998

The assessment of menstrual synchrony: comment on Weller and Weller (1997)

A. Weller and L. Weller (1997) claimed to report "the definitive study of menstrual synchrony" (p. 148). To allow for cycle variability, they used the following criterion for synchrony: It occurred in 2 out of 3 months. The underlying assumption of the state of menstrual synchrony is that cycle length variability is minimal. The present article uses a random selection of cycle lengths from a distribution described by R. F. Vollman (1977) to illustrate how variable cycle lengths cause a fluctuation from synchrony to a synchrony. A. Weller and L. Weller's (1997) study is not, therefore, conclusive, and future studies of menstrual synchrony should include an assessment of cycle variability as well as onset difference.

Female↗
PubMed1975

Polymorphisms in cyclically-varying environments.

We analysed both continuous and discrete two-allele models of cyclically-varying environments with an arbitrary degree of dominance. In continuous models, the gene frequency fluctuates with the period of the environmental oscillation. For the discrete case, the calculations were carried out to second order in selection. In contrast to the continuous models, and depending on the amount of dominance and the intitial gene frequency, fixation is possible as well as polymorphism.

Environment↗
PubMed2003

Early stage kinetics in a unified model of shear-induced demixing and mechanical shear banding instabilities.

We present a unified model of shear-induced demixing and "mechanical" shear banding instabilities in polymeric and surfactant solutions, by combining a simple flow instability with a two-fluid approach to concentration fluctuations. Within this model, we calculate the "spinodal" limit of stability of initially homogeneous shear states to demixing/banding, and predict the selected length and time scales at which inhomogeneity first emerges after a shear start-up "quench" into the unstable region, finding qualitative agreement with experiment. Our analysis is the counterpart, for this driven phase transition, of the Cahn-Hilliard calculation for unsheared fluid-fluid demixing.

Journal Article↗
PubMed1998

Polymorphisms and fluctuations in copy number of amplified esterase genes in Culex pipiens mosquitoes.

In Culex pipiens mosquitoes, A2 esterase alleles are co-amplified with B2 esterase alleles in response to selection with organophosphate insecticides. In this study the amplified A2 and B2 sequences were compared between twelve strains from four continents by restriction mapping. The restriction maps were almost identical in each strain throughout 22 kb surrounding the genes, suggesting that this represents a constant core sequence. A polymorphism was found in two strains collected from Egypt and Kenya in the mid 1980s. This polymorphism was present in all copies of the amplicon, which suggests that a mechanism of sequence homogenization was operating, i.e. concerted evolution. These two strains were almost certainly descendants from the same population and migration probably occurred along the River Nile. Although the maps were almost identical in each strain, dot blotting demonstrated that amplification levels differed by up to 13-fold between strains. Thus the presence of the A2-B2 haplotype cannot be used to indicate the level of amplification or any particular degree of resistance.

Animals↗
PubMed2005

Effect of intermittent fasting and refeeding on insulin action in healthy men.

Insulin resistance is currently a major health problem. This may be because of a marked decrease in daily physical activity during recent decades combined with constant food abundance. This lifestyle collides with our genome, which was most likely selected in the late Paleolithic era (50,000-10,000 BC) by criteria that favored survival in an environment characterized by fluctuations between periods of feast and famine. The theory of thrifty genes states that these fluctuations are required for optimal metabolic function. We mimicked the fluctuations in eight healthy young men [25.0 +/- 0.1 yr (mean +/- SE); body mass index: 25.7 +/- 0.4 kg/m(2)] by subjecting them to intermittent fasting every second day for 20 h for 15 days. Euglycemic hyperinsulinemic (40 mU.min(-1).m(-2)) clamps were performed before and after the intervention period. Subjects maintained body weight (86.4 +/- 2.3 kg; coefficient of variation: 0.8 +/- 0.1%). Plasma free fatty acid and beta-hydroxybutyrate concentrations were 347 +/- 18 and 0.06 +/- 0.02 mM, respectively, after overnight fast but increased (P < 0.05) to 423 +/- 86 and 0.10 +/- 0.04 mM after 20-h fasting, confirming that the subjects were fasting. Insulin-mediated whole body glucose uptake rates increased from 6.3 +/- 0.6 to 7.3 +/- 0.3 mg.kg(-1).min(-1) (P = 0.03), and insulin-induced inhibition of adipose tissue lipolysis was more prominent after than before the intervention (P = 0.05). After the 20-h fasting periods, plasma adiponectin was increased compared with the basal levels before and after the intervention (5,922 +/- 991 vs. 3,860 +/- 784 ng/ml, P = 0.02). This experiment is the first in humans to show that intermittent fasting increases insulin-mediated glucose uptake rates, and the findings are compatible with the thrifty gene concept.

Adult↗
PubMed2003

Resolution enhancement of pHe+ atomic line profiles measured with a pulsed dye laser and a Fizeau wavelength meter.

A Fizeau wavelength meter was used to compensate for fluctuations in the longitudinal mode structure and wavelength of a pulsed dye laser. The average laser linewidth was effectively narrowed by selection of laser pulses with a single longitudinal mode. These techniques were recently employed to measure some atomic transition wavelengths in pHe+ to fractional precisions greater than 1 part in 10(7). The wavelengths were absolutely calibrated against iodine or tellurium lines by absorption spectroscopy or against neon or argon lines by optogalvanic spectroscopy.

Journal Article↗
PubMed2004

Insulin gene profile cycles with season of birth of future diabetic children and their relatives.

BACKGROUND: HLA class II gene pattern and IA-2A antibody positivity, revealing selected risks for prediction of type 1 diabetes mellitus (DM1), were previously shown to be cycling roughly in parallel with seasonally fluctuating frequencies of births of future diabetic children. Is this also true for insulin genotyping? Is this also true for births of the healthy close relatives of children with DM1? PATIENTS AND METHODS: In 98 Slovak children with DM1 and in 60 healthy parents and siblings, two single nucleotide polymorphisms of the insulin gene (-23 Hph I; +1127 Pst I) were typed. Results were expressed as score 0 (maximal risk) up to 2 (minimal risk or protection), or 0-4 for the sum of both scores. Birth seasonality of these risk scores was tested by Halberg cosinor regression. RESULTS: Results were similar for the two alleles; therefore, the summed risk score was evaluated. The DM1 risk from the insulin gene pattern in births of future diabetics cycled significantly semi-annually, with maxima around the spring and autumn equinoxes. In the relatives, a significant annual and extremely pronounced quarterly peaking rhythm was found, with maximum risk in births around the autumn equinox and shortly after the winter solstice. Significant protection peaks are present in late winter, spring and summer. CONCLUSION: The highest frequency of Coxsackie infections in the Slovakian child population, and of 'diabetic' births and manifestations, found earlier together with maximal risks from HLA II and IA-2A antibodies in late summer and early autumn, is now confirmed also for the insulin gene pattern in diabetic children and even also for their healthy close relatives.

Adult↗
PubMed2000

[Interdependency between titers of aniretinal antibodies and selected immune system parameters in serum of patients with endogenous posterior uveitis].

PURPOSE: To evaluate serum antiretinal antibodies and selected immune system activity parameters in patients with endogenous posterior uveitis. MATERIAL AND METHODS: 50 patients--29 women (58%) and 21 men (42%)--aged 15-70 with idiopathic posterior uveitis were examined. Intraocular inflammation intensity was scored on standard uveitis grading system prepared by BenEzra et al. In all cases selected parameters of serum immune system activity--immunoglobulins: IgA, IgG, IgM, IgE, complement proteins: C3c, C4, circulating immune complexes (CIC) and autoantibodies: ANA, ANCA, ACA, were detected. The serum levels of ARA were determined by indirect immunofluorescence test on normal monkey retina as a substrate and FITC-labelled anti-human IgA, IgG, IgM serum (Euroimmun, Germany). All immune system parameters were assessed in active stage of the disease and 1, 3, 6, 12 months after the beginning of immunosuppressive therapy. RESULTS: In 38 patients (76%) non specific abnormalities of serum immune system activity parameters were found. During the follow-up period the changes in serum concentrations of immune system parameters were not statistically significant. Before treatment ARA were present in serum of 40 patients (80%). The distinct decreasing of serum ARA levels was present during the whole time of observation. The statistical analysis did not show any correlation between the serum concentration of selected immune system parameters and ARA. However, the presence of two various tendencies between ARA and CIC serum levels co-fluctuations were observed. In subjects with absence or low CIC serum concentrations, high serum ARA levels were found and the uveitis was severe. In cases with high CIC serum concentrations, low ARA levels were present and the disease course was mild. CONCLUSION: The interdependency between CIC and ARA has probably an essential role in the pathogenesis of idiopathic posterior uveitis.

Adolescent↗
PubMed2001

[Guidelines for antibiotic agents in the field of respiratory tract surgery].

This paper provides information on the use of antibiotic agents during the postoperative period from three aspects. 1) It is important to evaluate the risk factors of postoperative infection based on the patient's preoperative condition. Diseases treated with respiratory tract surgery are frequently caused by heavy smoking. Therefore it must be remembered that the patients may have low respiratory function. 2) In the prevention of postoperative infection, the special circumstances after respiratory surgery (e.g., the disintegration of the clearance system in the airway caused by the dissection of lymph nodes, the suppression of respiration, and cough caused by thoracotomy accompanied by resection of the ribs) must be considered. Therefore we usually administer antibiotic agents for 3 to 4 days. In general, we select second-generation cephalosporins, be cause gram-negative rod infection frequently occurs. 3) Postoperative infection is diagnosed based on fluctuations in fever, laboratory data (number of white blood cells and C-reactive protein), chest X-ray findings, and properties of drainage fluid. When bacteria are not identified, we must consider MRSA as a gram-positive bacterium and Pseudomonas aeruginosa as a gram-negative bacterium. After the identification of bacteria causing the infection, the antibiotic agents may be changed based on the results of sensitivity tests. The appropriate usage of antibiotic agents in the field of respiratory tract surgery is discussed based on actual clinical experience in our department.

Anti-Bacterial Agents↗
PubMed2001

Semiology of typical and atypical Rolandic epilepsy: a video-EEG analysis.

Since the first descriptions of Rolandic Epilepsy or benign epilepsy with centrotemporal spikes (BECTS), typical and atypical forms have been reported. Indeed, classical focal seizures are sometimes associated with various atypical ictal symptoms and cognitive or behavioural disorders. In an effort to define early clinical and EEG criteria allowing early distinction between typical and atypical forms, we recently conducted a prospective study in a cohort of children with Rolandic Epilepsy. The results of this study have been reported elsewhere. We now discuss the semiological characteristics, and comment on the video-EEG data collected during this study. Symptoms were classified into three major categories: "classical focal seizures"; "spike and wave related symptoms"; and "paraictal symptoms". Classical focal seizures constitute the electroclinical expression of the development and the propagation of a focal cortical neuronal discharge. "Spike and wave related symptoms" are brief neurological or neuropsychological phenomena having a relatively strict temporal relation with individual components of isolated focal or generalized spikes and waves. "Paraictal symptoms" consist of acquired progressive and fluctuating motor or cognitive deficits and are not directly correlated with Todd paralysis. We present detailed video-EEG material of selected cases and discuss the usefulness of such distinctions in terminology. We suggest that variability in clinical expression probably reflects the implication of different pathophysiological mechanisms, which in turn could explain differences in sensitivity to treatment. (Published with videosequences.)

Arm↗
PubMed1953

Some ecological observations on houseflies in Egypt.

Observations were made over a three-year period (1949-51) on the occurrence of peaks and depressions in the housefly population of Talbia, a small village in a rural district near Cairo. The results, illustrated by eight figures, are based on counts of flies collected on wooden grids placed at selected sites.Two peaks and two depressions occur annually-in spring and autumn, and at midsummer and in winter, respectively. These fluctuations in fly population appear to be associated with changes in temperature, although a certain irregularity in the findings suggests that some other factor-such as the number of manure heaps accumulated at various times of the year-may be involved. Temperature also affects the concentration of flies at indoor and outdoor haunts; an increase above 23.5 degrees C tends to drive them indoors. There is no indication that humidity influences the density of fly populations.

Animals↗
PubMed2005

A study of fragment-based protein structure prediction: biased fragment replacement for searching low-energy conformation.

A novel fragment replacement strategy for the fragment-based protein structure prediction is proposed. Despite the recent advance of de novo prediction of protein tertiary structure, intricate protein topologies still exist at unsatisfactory prediction quality. Although this difficulty is in part due to the accuracy of energy functions, it also relates to the search ability of sampling methods. To enhance the global optimization method that finds low-energy conformations, this study tests a biased sampling approach. The proposed approach is inspired by the fact that local structures of a protein have geometrical rigidity and flexibility. For capturing the pivotal local structures to generate various topologies, this approach first measures the energetic fluctuation of target fragments on dihedral angles of a protein, and then the quantity is converted to probability used by probabilistic selection of fragment replacement. Due to the requirement of the dihedral angles, a Genetic Algorithm implements the proposed idea, and experimental results show that the GA is capable of providing the dihedral angles as template-like proteins. The results suggest that the proposed approach can reach low-energy conformations with comparable prediction quality to that of an existing method. Interestingly, the low-energy states were associated with the frequent replacement of fragments in natively-coil regions. However, unfavorable compactification of the predicted models was observed. All experimental data are available at http://www.proteinsilico.org/PRO/.

Algorithms↗
PubMed1987

[Synthesis and metabolism of estriol conjugates].

As an indicator of fetal well being, the urinary estriol value is widely utilized. But the discrepancy between the results of NST and urinary estriol value has recently been pointed out. The estimation of plasma estriol is also recommended as a more reliable means of fetal assessment than that of urinary estriol. The purpose of the study is to clarify the patterns of estriol conjugates in maternal blood, retroplacental blood and cord blood, and further to elucidate the metabolism and secretion of each conjugate in organs and to determine the most useful conjugate as a source of fetal information. In normal pregnancy urine, estriol glucosiduronate is the dominant component of urinary estriol. In preeclampsia, the percentage of G decreased and that of G-S increased. In retroplacental blood, G-S is the main conjugate. On the other hand in cord blood, S is the dominant conjugate. The placental perfusion experiment revealed that the placenta hydrolyzed each conjugate to a free form and did not convert one conjugate to another. Periodical determination of plasma estriol conjugates in pregnant women revealed that the G-S fraction fluctuated most during parturition. The importance of liver as a possible site for estriol conjugation and the role of kidney in selective clearance of estriol conjugates are discussed.

Estriol↗