Showing papers by "Katholieke Universiteit Leuven published in 1991"

The human leukemia cell line, THP-1: A multifacetted model for the study of monocyte-macrophage differentiation

Abstract: THP-1 is a human monocytic leukemia cell line. After treatment with phorbol esters, THP-1 cells differentiate into macrophage-like cells which mimic native monocyte-derived macrophages in several respects. Compared to other human myeloid cell lines, such as HL-60, U937, KG-1, or HEL cell lines, differentiated THP-1 cells behave more like native monocyte-derived macrophages. Because of these characteristics, the THP-1 cell line provides a valuable model for studying the mechanisms involved in macrophage differentiation, and for exploring the regulation of macrophage-specific genes as they relate to physiological functions displayed by these cells.

Hyper-Rayleigh scattering in solution.

Abstract: Hyper-Rayleigh scattering in solution is used for the determination of the hyperpolarizability of nonlinear optical molecules. Obtaining the first hyperpolarizability \ensuremath{\beta} without having to independently determine the dipole moment \ensuremath{\mu} and the second hyperpolarizability \ensuremath{\gamma} is an advantage over the electric-field-induced second-harmonic generation technique. Values of the first hyperpolarizability \ensuremath{\beta} of 23\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}30}$ esu for para-nitroaniline, 105\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}30}$ esu for 4-methoxy-4'-nitrostilbene, and 95\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}30}$ esu for 4-hydroxy-4'-nitrostilbene dissolved in chloroform have been obtained. The equivalent-internal-field model is shown to hold for small saturated molecules.

The diagnostic performance of computer programs for the interpretation of electrocardiograms.

Abstract: Background. Computer programs for the interpretation of electrocardiograms (ECGs) are now widely used. However, a systematic assessment of various computer programs for the interpretation of ECGs has not been performed. Methods. We undertook a large international study to compare the performance of nine electrocardiographic computer programs with that of eight cardiologists in interpreting ECGs in 1220 clinically validated cases of various cardiac disorders. ECGs from the following groups were included in the sample: control patients (n = 382); patients with left ventricular hypertrophy (n = 183), right ventricular hypertrophy (n = 55), or biventricular hypertrophy (n = 53); patients with anterior myocardial infarction (n = 170), inferior myocardial infarction (n = 273), or combined myocardial infarction (n = 73); and patients with combined infarction and hypertrophy (n = 31). The interpretations of the computer programs and the cardiologists were compared with the clinical diagnoses made independently of the ECGs, and the computer interpretations were compared with those of the cardiologists. Results. The percentage of ECGs correctly classified by the computer programs (median, 91.3 percent) was lower than that for the cardiologists (median, 96.0 percent; P < 0.01). The median sensitivity of the computer programs was also significantly lower than that of the cardiologists in diagnosing left ventricular hypertrophy (56.6 percent vs. 63.9 percent, P < 0.02), right ventricular hypertrophy (31.8 percent vs. 46.6 percent, P < 0.01), anterior myocardial infarction (77.1 percent vs. 84.9 percent, P < 0.001), and inferior myocardial infarction (58.8 percent vs. 71.7 percent, P < 0.0001). The median total accuracy level (the percentage of correct classifications) was 6.6 percent lower for the computer programs (69.7 percent) than for the cardiologists (76.3 percent; P < 0.001). However, the performance of the best programs nearly matched that of the most accurate cardiologists. Conclusions. Our study shows that some but not all computer programs for the interpretation of ECGs perform almost as well as cardiologists in identifying seven major cardiac disorders.

Hevein: an antifungal protein from rubber-tree (Hevea brasiliensis) latex

Abstract: Several chitin-binding proteins were isolated from the “bottom fraction” of Hevea brasiliensis (Mull.) Arg. latex. One of these chitin-binding proteins is hevein, a small monomeric protein which strongly resembles the lectin from stinging nettle (Urtica dioica L.). Like the latter, hevein showed strong antifungal activity against several fungi in vitro. The possible involvement of this protein in the defense against invasion by potentially pathogenic fungi is discussed.

A Mathematica™ Package for Computing Operator Product Expansions

Abstract: A general purpose Mathematica™ package for computing Operator Product Expansions of composite operators in meromorphic conformal field theory is described. Given the OPEs for a set of “basic” fields, OPEs of arbitrarily complicated composites can be computed automatically. Normal ordered products are always reduced to a standard form. Two explicit examples are presented: the conformal anomaly for superstrings and a free field realization for the $\widehat{B_2}$ Kac-Moody-algebra.

Propagation characteristics of Boolean functions

Abstract: The relation between the Walsh-Hadamard transform and the auto-correlation function of Boolean functions is used to study propagation characteristics of these functions. The Strict Avalanche Criterion and the Perfect Nonlinearity Criterion are generalized in a Propagation Criterion of degree k. New properties and constructions for Boolean bent functions are given and also the extension of the definition to odd values of n is discussed. New properties of functions satisfying higher order SAC are derived. Finally a general framework is established to classify functions according to their propagation characteristics if a number of bits is kept constant.

From Localised Social Structures to Localities as Agents

Abstract: The paper is an attempt to clarify the concept of locality for further research by investigating two common meanings of locality: locality as localised social structure and locality as agent. The first is developed through linking local dependence to territorial forms of the division of labour; to enable this a new concept, ‘the scale division of labour’, is introduced. This concept describes what roles in the social division of labour exist at different scales, and hence of what social relations the localised social structure consists. The locality as agent concept is developed from the idea of locally dependent actors with interests in the same locality forming an alliance, acting together to develop and implement strategies to further their interests. This avoids spatial fetishism because locality was first defined not in physical terms, but as localised social structure.

Subspace algorithms for the stochastic identification problem

Abstract: The authors derive a novel algorithm to consistently identify stochastic state space models from given output data without forming the covariance matrix and using only semi-infinite block Hankel matrices. The algorithm is based on the concept of principle angles and directions. The authors describe how these can be calculated with only QR and QSVD decompositions. They also provide an interpretation of the principle directions as states of a non-steady-state Kalman filter. With a couple of examples, it is shown that the proposed algorithm is superior to the classical canonical correlation algorithms. >

Mean and range of the ambulatory pressure in normotensive subjects from a meta-analysis of 23 studies

Abstract: To perform a meta-analysis of published reports in an attempt to determine the mean and range of normal ambulatory blood pressure (BP), 23 studies including a total of 3,476 normal subjects were reviewed. Most studies were compatible with a mean 24-hour BP in the range of 115 to 120/70 to 75 mm Hg, a mean daytime BP of 120 to 125/75 to 80 mm Hg, and a mean nighttime BP of 105 to 110/60 to 65 mm Hg. With weighting for the number of subjects included in the individual studies, the 24-hour BP averaged 118/72 mm Hg, the daytime BP 123/76 mm Hg, and the nighttime BP 106/64 mm Hg. The night/day pressure ratio averaged 0.87 for systolic and 0.83 for diastolic BP, with ranges across the individual studies from 0.79 to 0.92 and from 0.75 to 0.90, respectively. If the mean +/- 2 standard deviation interval in the various studies was considered normal, the range of normality was on average 97 to 139/57 to 87 mm Hg for the 24-hour BP, 101 to 146/61 to 91 mm Hg for the daytime BP, and 86 to 127/48 to 79 mm Hg for the nighttime BP. Until the results of prospective studies on the relation between the ambulatory BP and the incidence of cardiovascular morbidity and mortality become available, the aforementioned intervals, which summarize the experience of 23 investigators, could serve as a temporary reference for clinical practice.

Cytokines and their interactions with other inflammatory mediators in the pathogenesis of sepsis and septic shock.

Abstract: Sepsis and its potentially lethal complication, septic shock, belong to the most frequent causes of mortality in modern clinics and, especially, in intensive care units. Moreover, the incidence of this condition is steadily increasing. Multiple circumstances underlie this increasing trend: increasing longevity in developed countries with attendant susceptibility to infections; increased use of immunosuppressive therapy, e.g. for patients with organ transplants; and increased u-e of extensive and sophisticated surgery that allows survival for patients who would otherwise die of causes such as cancer, extensive trauma, burns, extensive blood loss. etc. The pathogenesis of shock has been a matter of intensive study for many years. The vascular and tissue alterations in shock have of old been recognized to be mainly due to the pharmacological actions of plasmaand tissue-derived mediators. Amongst these mediators, the so-called cytokines have recently received increasing attention of investigators. Not only have ‘older’ members of this molecular family (e.g. the endogenous pyrogens) been fully characterized, but new members have also been discovered. Moreover, the complex of interactions amongst cytokines, the socalled cytokine network, is now being progressively disentangled. Here we wish to review current views on the role of the cytokine network in sepsis. Before doing so, it may be useful to recall that the potentially lethal complications of sepsis always comprise three elements (Fig. 1). Any one of these may act

Control of asymmetrical bimanual movements.

Abstract: When movements are performed together in the upper-limbs, a strong tendency emerges to synchronize the patterns of motor output. This is most apparent when trying to do different things at the same time. The present experiment explored the simultaneous organization and control of spatiotemporally different movements. There were two practice conditions: symmetrical and asymmetrical. In the symmetrical condition, subjects performed a series of unidirectional elbow flexion movements, followed by a series of elbow flexion-extension-flexion (reversal) movements in both limbs simultaneously. In the asymmetrical practice condition, subjects performed the unidirectional movement in the left limb together with the reversal movement in the right limb. Findings revealed a tendency for each limb movement to assimilate the features of its counterpart under the latter condition. This effect was “asymmetrical” in that the unidirectional movement was more attracted to the reversal movement than vice versa. Nevertheless, subjects were able to partly suppress this synchronization tendency as was evident from the moderate cross correlations between the angular acceleration patterns of both limb movements and from an increasingly successful differentiation of the activity levels in the right and left limb muscles. All together, these findings provide evidence for some degree of parallel control of spatiotemporally different actions. The data are discussed in view of the possible suppression of a bilaterally distributed motor control system, that is mainly held responsible for activiting proximal limb musculature.

The effects of the addition of sufentanil to 0.125% bupivacaine on the quality of analgesia during labor and on the incidence of instrumental deliveries.

Abstract: In a double-blinded, randomized, prospective multi-center study of 695 women, we investigated whether epidural injection of sufentanil added to 0.125% bupivacaine with epinephrine (1:800,000) reduces the total amount of local anesthetic required, resulting in less motor blockade and reduced incidence of instrumental deliveries, and improves the quality of analgesia provided by this low concentration of local anesthetic without jeopardizing the safety of the baby. In addition, other potential benefits of sufentanil (such as decrease in the incidence of shivering) and side effects were examined. It was found that adding incremental doses of 10 micrograms sufentanil up to a maximum of 30 micrograms reduced the incidence of instrumental deliveries from 36 to 24% (P less than 0.01) and significantly improved quality and duration of analgesia without depressing the neurobehavioral status of the baby. No other benefits from adding sufentanil were found. The only side effect that occurred more frequently after sufentanil was pruritus. We conclude that epidural injection of 10-30 micrograms sufentanil added to 0.125% bupivacaine with epinephrine (1:800,000) improved the quality of analgesia during labor and reduced the incidence of instrumental deliveries without jeopardizing the safety of the baby.

Operative treatment of ankle fractures in adults: correlation between types of fracture and final results.

Abstract: By means of a simple and easy classification, namely uni, bi- and trimalleolar ankle fractures, and the localization of the fracture at the level of the fibula; all of the 612 ankle fractures that were surgically treated at the Leuven University Hospital were easily classified. In 590 cases the results were collected 1 year after the operation by means of an evaluation system based on symptoms, clinical findings and radiographic findings. The influence of the type of fracture was analysed and led to the following conclusion: 1. Unimalleolar fractures have a better prognosis than trimalleolar fractures. 2. An isolated medial malleolar fracture gives a worse final result than an isolated lateral malleolar fracture. 3. Multimalleolar fractures, including the medial malleolus, have a worse prognosis than multimalleolar fractures without medial malleolar fractures. 4. Even after perfect internal fixation, the presence of a posterior fragment larger than one-third of the articular surface leads to a worse final result than a small unfixed fragment. 5. Weber's classification may not be useful for prognosis.

Fermentable sugars and intracellular acidification as specific activators of the RAS-adenylate cyclase signalling pathway in yeast: the relationship to nutrient-induced cell cycle control.

Abstract: The RAS proteins of the yeast Saccharomyces cerevisiae fulfil a similar control function on yeast adenylate cyclase as the mammalian Gs proteins on mammalian adenylate cyclase. The discovery that glucose and other fermentable sugars act as specific activators of the RAS-adenylate cyclase pathway in yeast appeared to offer a mechanism for the way in which at least one nutrient would control progression over the start point in the G1 phase of the yeast cell cycle by means of this pathway. Recently, however, evidence has been obtained to show that the glucose-activation pathway of adenylate cyclase is a glucose-repressible pathway and therefore not operative during growth on glucose. In addition, mutant strains were obtained which lack the glucose-activation pathway and show normal exponential growth on glucose. This appears to confine the physiological role of this pathway to control of the transition from the derepressed state (growth on respirative carbon sources) to the repressed state (growth on fermentative carbon sources) by means of an already well-documented cAMP-triggered protein phosphorylation cascade. Intracellular acidification also stimulates the RAS-adenylate cyclase pathway, which might constitute a rescue mechanism for cells suffering from stress conditions. The presence of a nitrogen source does not stimulate the RAS-adenylate cyclase pathway. Although other nutrient signals for the pathway might still be discovered, it appears more and more likely that the well-known requirement of cAMP for progression over the start point of the yeast cell cycle is limited to providing a basal cAMP level rather than acting as a second messenger for an extracellular signal.(ABSTRACT TRUNCATED AT 250 WORDS)

Heritability of aerobic power and anaerobic energy generation during exercise

Abstract: Twenty-nine pairs of monozygotic twins and 19 pairs of dizygotic twins, all male, ages 18–31 yr, performed a graded uninterrupted exercise test on the bicycle ergometer to exhaustion. By use of pat...

Weights of exponential sums, intersection cohomology, and Newton polyhedra

Abstract: (1.1) Throughout this paper k always denotes a finite field Fq with q elements, and E a prime number not dividing q. The algebraic closure of a field K is denoted by / ( . Let ~b: k--+ C • be a nontrivial additive character, and ~ , the Qt-sheaf on A~ associated to ~ and the Artin-Schreier covering t q t = x. For a morphism f : X --+ A~, with X a scheme of finite type over k, one considers the exponential sum S(f ) = ~Xtk)~b(f(x)). By Grothendieck's trace formula we have