Copper carbonate as a solid-bed reactor for spectrophotometric determination of doxycycline and oxytetracycline in an unsegmented continuous flow ass…

1993

The FIA-spectrophotometric determination of doxycycline was carried out by reaction of the drug with cupric ions entrapped in a polymeric material in a packed-bed reactor: the complex formed was then injected into a manifold with an alkaline solution as carrier. The developed colour was monitored at 395.0 nm. The method was applied to the determination of doxycycline in different pharmaceutical formulations. The calibration graph for doxycycline hyclate was linear over the range 10.0-80.0 mg ml-1 (n = 8) with a relative standard deviation of 1.4% (at 25 mg ml-1) and a sample throughput of 128 h-1. The proposed procedure was also applied to the determination of oxytetracycline in pharmaceuti…

An ab initio study of the tautomeric equilibria of the N-oxides of hydroxypyridines in the vapour phase

1993

Abstract An ab initio self-consistent field molecular orbital study of the N-oxides of hydroxypyridines has been carried out. The optimized structures have been obtained at the 6-31G ∗ level, and the energy values have been computed at the 6-31G ∗ and MP2-6-31G ∗ //6-31G ∗ levels. The tautomerization energies for the three couples of systems in the vapour phase have been evaluated.

Divergent in vivo and in vitro antileukemic activity of recombinant interferon beta in patients with chronic-phase chronic myelogenous leukemia

1993

It was the aim of this study to investigate the antileukemic activities of recombinant interferon beta (rIFN beta) in chronic-phase CML in vitro and in vivo. Nine patients in the early chronic-phase of CML were treated in a phase-II trial with escalating doses of rIFN beta. In parallel, antiproliferative and immunomodulatory activities of rIFN beta and rIFN alpha 2b were studied in vitro. rIFN beta exhibited a significantly higher antiproliferative activity on hematopoietic progenitor cells of CML patients in vitro than rIFN alpha 2b. In contrast, only very limited clinical antileukemic efficacy of rIFN beta was observed. None of the patients achieved a complete or partial hematologic respo…

Expression of intercellular adhesion molecule 1 (ICAM-1, CD54) in colonic epithelial cells.

1993

The expression of intercellular adhesion molecule-1 (ICAM-1, CD54) was examined in 16 surgically removed colonic tumours and two colonic carcinoma cell lines. Immunohistochemistry showed a varying percentage of ICAM-1 positive colonic carcinoma cells in 9/16 tissue specimens, while normal colonic tissue (apart from a slight reactivity of endothelial cells) was not stained. The presence of the ICAM-1 molecule on the cell surface and the expression of ICAM-1 mRNA were investigated for two colonic carcinoma cell lines. It was possible to enhance the expression of ICAM-1 considerably by incubating the cells in the presence of inflammatory cytokines in HT-29 and CaCo-2 cells. The responsiveness …

Linear chain surfactants at a planar interface: a comparative Monte Carlo study of several lattice models

1993

Linear chain surfactants in a densely packed arrangement (such as alkane chains in lipid monolayers in the “uniform tilt” structures) are described by a crude coarse-grained model where the endgroups grafted on the interface form a regular lattice and the chains are described by the bond fluctuation model with chains containing N = 4 effective monomers only. Square-well interactions between the monomers are studied for both the attractive and repulsive case for three choices of the interaction range. None of these models exhibits a structure with uniform tilt. For attractive interactions the last bond has a strong tendency to fold back thus leading to a very high density close to the interf…

A statistical approach towards a regionalization of daily rainfall in Sri Lanka

1993

Regionalization of daily rainfall in Sri Lanka was examined using orthogonal factor analysis (OFA) based on daily rainfall data of 42 stations for a 15-year period (1971–1985). The number of potential rainy days was computed from the original data matrix and subjected to S-mode OFA. The first 10 orthogonal factors were shown as highly significant, explaining 65.1 per cent of the total variance of the whole data matrix, where the level of eigenvalues represented was > 1.0. Noticeably, the 10 orthogonal factors clearly revealed the different homogeneous daily rainfall regions in Sri Lanka (labelled as A to J), according to the orthogonal factor high loadings matrix. Delimitation of the daily …

FIGARO IV: Large-area balloon-borne telescope to study rapid time variabilities in the gamma-ray sources at energies above 50 MeV

1993

We present a new γ-ray telescope based on the Limited Streamer Tube technology, used as tracking chambers to detect photons above 100 MeV. This technique allows to obtain very large sensitive areas (16 m2 in our experiment), together with a good angular resolution for payloads embarcable in high-altitude balloon flights. The capability to collect a large signal in a short exposure time makes the telescope particularly suitable and competitive with respect to satellite-based detectors for studying both periodic and random time variabilities on galactic and extragalactic γ-ray sources.

Actions of alpha-adrenoceptor blocking agents on two types of intracellular calcium stores mobilized by noradrenaline in rat aorta.

1993

In isolated rat aortic strips noradrenaline induces a biphasic contractile response in Ca-free medium, associated with two different intracellular calcium pools, one of which is common to caffeine. We analyzed the mechanisms involved in the depletion and repletion of both intracellular Ca pools sensitive to noradrenaline in different experimental procedures in presence of prazosin, phentolamine and yohimbine. At 37 degrees C the alpha-adrenergic blocking agents inhibited contractile responses to noradrenaline in Ca-free medium, with prazosin being highly selective. alpha 2-adrenoceptors probably do not participate in the release of Ca from internal stores, as no contractile response was obs…

A Phase II Study of Levofolinic Acid and 5-Fluorouracil Plus Cisplatin in Patients with Advanced Head and Neck Squamous Cell Carcinoma

1993

Forty patients with advanced squamous cell carcinoma of the head and neck (SCHNC) were treated with a combination of levofolinic acid 100 mg/m2+5-fluorouracil 375 mg/m2 in a 4-hour infusion plus cisplatin 20 mg/m2 in a 2-hour infusion for 5 consecutive days, repeated every 21-28 days. In the group of 20 previously untreated patients, a 90% overall response rate (ORR) with a 30% complete response rate (CRR) was obtained. In the group of 20 pretreated patients with recurrent and/or metastatic SCHNC, a 55% ORR with 15% CRR was achieved. This treatment was given on an outpatient basis and was generally very well tolerated with only 2 patients requiring hospitalization. Grade 1-2 gastrointestina…

AIDS and the Central Nervous System: Examining Pathobiology and Testing Therapeutic Strategies in the SIV-Infected Rhesus Monkey

1993

Oldest Homo and Pliocene biogeography of the Malawi Rift

1993

The Malawi Rift and Pliocene palaeofaunas, which include a hominid mandible attributed to Homo rudolfensis, provide a biogeographical link between the better known Plio-Pleistocene faunal records of East and Southern Africa. The Malawi Rift is in a latitudinal position suitable for recording any hominid and faunal dispersion towards the Equator that was brought on by increased aridity of the Late Pliocene African landscape. The evidence suggests that Pliocene hominids originated in the eastern African tropical domain and dispersed to southern Africa only during more favourable ecological circumstances.

Ising model universality for two-dimensional lattices

1993

We use the single-cluster Monte Carlo update algorithm to simulate the Ising model on two-dimensional Poissonian random lattices of Delaunay type with up to 80\,000 sites. By applying reweighting techniques and finite-size scaling analyses to time-series data near criticality, we obtain unambiguous support that the critical exponents for the random lattice agree with the exactly known exponents for regular lattices, i.e., that (lattice) universality holds for the two-dimensional Ising model.

<title>Studies of the activation background in CsI(Tl) detectors</title>

1993

CsI scintillation crystals are widely used as detection in (gamma) -ray astronomy observations. In the MeV energy region, one of the most important background sources in CsI is the (beta) decays induced in the crystal by cosmic ray protons and their secondaries. One recent idea for reducing this background is to use discrete detector arrays to reject the large amount of localized (beta) decay events. Two experiments were carried out with 1 cm3 CsI crystals bombarded with energetic proton beams and fast/thermal neutrons, with the aim of evaluating the effectiveness of this method in pixelated (1 cm3) CsI detectors. The ratio of the number of decays resulting in single site and multiple site …

Mise au point d'un modèle aromatique de fromage à pâte molle application au camembert

1993

National audience

Caroténoïdes et cancérogénèse : influence de caroténoïdes alimentaires sur l'initiation de la cancérogénèse chimique

1993

National audience

Etude de la coopération entre Geotrichum candidum et Penicillium camenberti. Impact sur le profil aromatique et sur les qualités organoleptiques d'un…

1993

National audience

Optical determination of pH on surfaces using immobilized Fluorescent dyes.

1993

The attachment of pH-sensitive Fluorescent dyes on to hydroxylapatite for measuring the pH of small volumes is described. Fluorescein and acridine were used, both activated with reactive functions, such as isothiocyanate or succinimidyl ester groups, to enhance the possibility of a covalent linkage to the surface. First investigations were carried out on synthetic hydroxylapatite as the surface material. After the preparation of a particular surface with the fluorescent dye, steady-state and time-resolved fluorescence spectroscopies were employed for estimating the pH value of a solution applied to the surface. In this paper we present the results of our investigations done with both method…

A new method of anomeric protection and activation based on the conversion of glycosyl azides into glycosyl fluorides

1993

Glycosyl azides provide reliable anomeric protection stable to conditions for hydrolytic removal of ester groups, for reductive opening or release of acetalic diol protection, for the introduction of ether-type protection, and for glycosylation processes. The utility of this anomeric protection is further enhanced as glycosyl azides may be converted into glycosyl fluorides, which can be activated for glycosylation reactions. To this end, glycosyl azides have been subjected to 1,3-dipolar cycloaddition with di-tert-butyl acetylenedicarboxylate. On treatment with hydrogen fluoride-pyridine complex the N-glycosyl triazole derivatives directly give glycosyl fluorides.

Behaviour of cyclic bank voles under risk of mustelid predation: do females avoid copulations?

1993

Mustelid odours have been shown to suppress breeding in captive bank voles (Clethrionomys glareolus) from cyclic populations (Ylonen 1989; Ylonen and Ronkainen 1994). The mechanism behind the suppression is unknown. Based on a series of behavioural trials and breeding experiments with pairs of bank voles in breeding condition, we suggest that the primary cause for breeding suppression is a change in female mating behaviour. Experimental female-male pairs (n=34) exposed to mustelid odour decreased their general activity compared to control pairs (n=34). When encountering males in behavioural trials, females exposed to stoat odour were more aggressive and actively avoided precopulatory behavi…

Parvalbumin-containing neurons in the cerebral cortex of the lizardPodarcis hispanica: Morphology, ultrastructure, and coexistence with GABA, somatos…

1993

The morphology, fine structure, and degree of colocalization with GABA, somatostatin, and neuropeptide Y of parvalbumin-containing cells were studied with immunocytochemistry in the cerebral cortex of the lizard Podarcis hispanica. Parvalbumin-containing cells make up a morphologically heterogeneous population of spine-free neurons, displaying the morphological features of nonprincipal cells previously described in Golgi studies. Electron microscopically, parvalbumin-immunoreactive cell bodies are similar in all cortical areas and layers. The perisomatic input is moderate in number, and boutons with either round clear vesicles or flattened vesicles were observed making asymmetric or symmetr…

Type-I interferons are potent inhibitors of interleukin-8 production in hematopoietic and bone marrow stromal cells

1993

Abstract nterleukin-8 (IL-8) is produced by many cell types upon stimulation with bacterial products or inflammation-associated cytokines such as tumor necrosis factor-alpha and IL-1. Interferons (IFNs) represent another group of cytokines that are induced by similar stimuli in inflammatory reactions. We show now that type-I IFNs are potent inhibitors of IL-8 expression in vitro and in vivo. A significant reduction of both secretion of IL-8 protein and accumulation of IL-8 mRNA in vitro was observed in several cell types comprising peripheral blood mononuclear cells (PBMNC) from healthy donors and from patients with chronic myelogenous leukemia (CML), the myelomonocytic cell line THP-1, and…

Proton Acid-induced Rearrangements of α-Alkynylestradiol Methyl Ethers

1993

When subjected to proton catalysis, the α-alkynylestradiol methyl ethers 1a and 1b furnish the Rupe or Meyer-Schuster rearrangement products 2, 4, and 5a. In the presence of sulfuric acid, α-ethynylestradiol 3-methyl ether (1a) is converted into the D-homosteroid 3a. The use of deuterated acids gives rise to the formation of the corresponding deuterated steroids 2b, 2c, 3b, and 5b. Some mechanistic implications of these results are also discussed.

Linear Dichroism in Photoemission from Oriented Molecules

1993

It is shown that oriented molecules reveal both Linear Dichroism (LD) and Linear Dichroism in the Angular Distribution (LDAD) of photoelectrons, which means a difference between photoelectron currents ejected at a definite angle by linearly polarized light of two mutually perpendicular polarizations. Measurements of LD and LDAD enable one to investigate the orientation of molecules and to make an essential step towards the complete quantummechanical experiment. As an example, LDAD in a model case of oriented heteronuclear diatomic molecules is presented.

A lumped model for a seismic source

1993

A lumped mechanical model is proposed and solved. This model is dynamically equivalent, in the mean field approximation, to a faulted lithosphere. The transition from the continuous system (modelled according to W. H. Prescott and A. Nur) to the lumped one, has been made by preserving all the relevant features exhibited by the continuous system. In particular the coupling between different components of the stress and strain tensors is suitably taken into account. The dynamics of the lumped system depends on six control parameters fixed by the physical properties of the continuous system. Three of the control parameters are dimensionless and describe: the seismic wave quality factor of the…

L'analyse fractale des zones métropolitaines: un aperçu méthodologique

1993

National audience; La croissance des agglomérations se manifeste dans la plupart des cas par J'apparition d'un tissu urbain amorphe et fragmenté même si le plan initial de la ville était conçu selon une géométrie régulière comme les bastides ou les villes nouvelles. Cette morphologie irrégulière de la surface bâtie ne semble pas liée à une situation lùstorique particulière et elle apparaît souvent en dépit des intentions des urbanistes qui tentent souvent d'imposer des plans compacts et réguliers. Ceci incite à supposer que la morphogenèse urbaine est le résultat de processus d'auto-organisation qui devraient se manifester par un principe d'ordre interne, si irrégulière que paraisse la morp…

Biotransformation of methylxanthines in mammalian cell lines genetically engineered for expression of single cytochrome P450 isoforms. Allocation of …

1993

V79 Chinese hamster cells genetically engineered for stable expression of single forms of rat cytochromes P450IA1, P450IA2, P450IIB1, human P450IA2, and rat liver epithelial cells expressing murine P450IA2 were used to allocate metabolic pathways of methylxanthines to specific isoforms and to test the suitability of such cell lines for investigations on drug interactions occurring at the cytochrome expressed. The cell lines were exposed to caffeine and/or theophylline and concentrations of metabolites formed in the medium were determined by HPLC. Caffeine was metabolized by human, rat and murine P450IA2, resulting in the formation of four primary demethylated and hydroxylated metabolites. H…

LE CISTI EPIDERMOIDI DELLA MILZA

1993

Le cisti epidermoidi della ilza sono rare e rappresentano appena il 10% della patologia cistica non parassitaria. Viene presentato un caso occorso in una piccola paziente di 6 anni, sottoposta a splenectomia per le enormi dimensioni della cisti e per la sua posizione anomale sull'ilo.

k-Weakly almost convex groups and ? 1 ? $$\tilde M^3 $$

1993

We extend Cannon's notion ofk-almost convex groups which requires that for two pointsx, y on then-sphere in the Cayley graph which can be joined by a pathl1 of length ≤k, there is a second pathl2 in then-ball, joiningx andy, of bounded length ≤N(k). Ourk-weakly almost convexity relaxes this condition by requiring only thatl1 ∝l2 bounds a disk of area ≤C1(k)n1 - e(k) +C2(k). IfM3 is a closed 3-manifold with 3-weakly almost convex fundamental group, then π1∞\(\tilde M^3 = 0\).

Transthoracic and transesophageal echocardiography to diagnose ventricular septal rupture

1993

BACKGROUND Rapid and accurate diagnosis of ventricular septal rupture (VSR) remains difficult, and the monitoring of hemodynamic deterioration is a prerequisite for the institution of adequate therapy. The timing of surgical repair is a matter of controversy. METHODS Transthoracic, transesophageal, color Doppler, and contrast echocardiography were evaluated in 17 patients with VSR in whom the diagnosis was confirmed by catheterization, surgery, or necropsy. RESULTS Routine transthoracic echocardiography visualized VSR in four out of 17 patients and, with additional views, in 12 out of 17 patients. Color Doppler echocardiography identified the rupture in 15 out of 16, and contrast echocardio…

Evidence that depletion of internal calcium stores sensitive to noradrenaline elicits a contractile response dependent on extracellular calcium in ra…

1993

1. Noradrenaline 1 microM induced a contractile response in rat isolated aorta in the presence or in the absence of extracellular Ca2+ with depletion of intracellular Ca2+ stores. Thereafter, during incubation in the presence of Ca2+, an increase in the resting tone was observed. Such a contractile response did not occur after exposure to caffeine or 5-hydroxytryptamine. 2. This increase in tension was inhibited in a concentration-dependent manner by alpha-adrenoceptor antagonists (prazosin, phentolamine and yohimbine), the non-specific relaxing compound, papaverine and by the Ca(2+)-entry blocker, nifedipine. Therefore, this contractile process is related to depletion of Ca2+ stores sensit…

EGFR and PCNA experession in oral squamous cell carcinomas—a valuable tool in estimating the patient's prognosis

1993

We investigated 100 cases of oral squamous cell carcinomas immunohistologically with respect to the expression of the epidermal growth factor receptor (EGFR) and the proliferating cell nuclear antigen (PCNA). The results were correlated with a new malignancy grading of the invasive tumour areas and the clinical outcome of the patients to estimate the individual prognosis. In conclusion, the amount of antigen expression of both antigens increases with the increasing grade of malignancy of the oral squamous cell carcinoma. Furthermore, there is a statistically significant correlation between the amount of antigen expression and the patient's prognosis. An overexpression of EGFR and PCNA is as…

Hole burning and pressure phenomena in chromoproteins

1993

Abstract We investigated the behavior of spectral holes under pressure at various frequencies within the inhomogeneous band for two proteins, namely myoglobin and horseradish peroxidase. In order to achieve narrow bandwidth hole burning, the heme chromophore was replaced by protoporphyrin IX and mesoporphyrin IX, respectively. In myoglobin, we found that the pressure induced shift of the holes varied in a strongly non-linear fashion, when the burn-frequency was tuned across the absorption band. In horseradish peroxidase the pressure shift was linear with burn-frequency but changed in a dramatic fashion upon complex formation with a substrate molecule. These observations are interpreted with…

ORDERING KINETICS IN QUASI-ONE-DIMENSIONAL ISING-LIKE SYSTEMS

1993

We present results of a Monte Carlo simulation of the kinetics of ordering in the two-dimensional nearest-neighbor Ising model in anL xM geometry with two free boundaries of length M≫L. This model can be viewed as representing an adsorbant on a stepped surface with mean terrace widthL. We follow the ordering kinetics after quenches to temperatures 0.25 ⩽ T/Tc ⩽ 1 starting from a random initial configuration at a coverage ofΘ=0.5 in the corresponding lattice gas picture. The systems evolve in time according to a Glauber kinetics with nonconserved order parameter. The equilibrium structure is given by a one-dimensional sequence of ordered domains. The ordering process evolves from a short ini…

Changes in the cerebrovascular effects of endothelin-1 and nicardipine after experimental subarachnoid hemorrhage.

1993

The role of endothelium-related factors in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage (SAH) has gained interest since the discovery of endothelin-1 (ET-1). We have examined, before and after SAH, the responsiveness of the cerebrovascular bed of the goat to ET-1, the sources of Ca2+ in ET-1-induced responses, and the ability of the Ca2+ entry blocker nicardipine to counteract them. Before SAH, injection of ET-1 into the cerebral circulation increased cerebrovascular resistance, thereby producing dose-dependent reductions in cerebral blood flow (CBF), which were prevented by nicardipine. In isolated middle cerebral arteries, ET-1 induced concentration-dependent contr…

Die isolierte Fraktur des Hamulus ossis hamati - eine leicht zu übersehende Handwurzelverletzung

1993

Stable expression of human cytochrome P450 1A1 cDNA in V79 Chinese hamster cells and metabolic activation of benzo[a]pyrene

1993

A V79 Chinese hamster cell line stably expressing human cytochrome P450 1A1 (CYP1A1) was obtained by chromosomal integration of the human CYP1A1 cDNA under the control of the SV40 early promoter. Chromosomal integration was verified by Southern analysis, and effective transcription of the human CYP1A1 cDNA was demonstrated by Northern analysis. The CYP1A1 cDNA-encoded protein was characterized by Western analysis using anti-rat CYP1A1. Intracellular association of CYP1A1 with the endoplasmic reticulum could be visualized by in situ immunofluorescence. Crude cell lysates of the V79 derived cell line was able to catalyze 7-ethoxyresorufin-O-deethylation (EROD) with an activity of about 50 pmo…