Effectiveness of a new tobramycin (0.3%) and dexamethasone (0.05%) formulation in the treatment of experimental Pseudomonas keratitis

OBJECTIVE

To quantitatively determine, in a Pseudomonas keratitis model, the anti-inflammatory and bactericidal properties of a new formulation of tobramycin (0.3%) and dexamethasone (0.05%) that utilizes a xanthan gum vehicle.

RESEARCH METHODS

In a randomized and masked fashion, rabbit corneas (n>/=16 eyes per group) were intrastromally injected with 10(3) colony-forming units (CFU) of P. aeruginosa. Eyes were untreated or were administered a single drop every 15 min between 16 and 17 h postinfection (PI) and then a single drop every 30 min between 17 and 22 h PI, a total of 15 drops of either 0.1% dexamethasone and 0.3% tobramycin (TobraDex; Tdex) or a new formulation 0.3% tobramycin and 0.05% dexamethasone with xanthan gum (TobraDex ST; ST). Slit lamp examination scores (SLE+/-SEM) were derived from grading seven parameters at 22 h PI. Rabbits were sacrificed at 23 h PI and the log CFU+/-SEM per cornea was determined.

RESULTS

Untreated eyes had SLE scores of 11.11+/-0.43 and had log CFU of 7.27+/-0.06. Eyes treated with Tdex, as compared to the untreated eyes, had significantly lower SLE scores (7.39+/-0.21, p<0.0001) and significantly fewer bacteria (6.32+/-0.29 log CFU, p=0.0213). Eyes treated with ST had a SLE score (6.56+/-0.19) that was significantly lower than both the untreated eyes (p<0.0001) and the eyes treated with Tdex (p=0.0124). Furthermore, eyes treated with ST had significantly fewer log CFU (5.78+/-0.30) than untreated eyes (p=0.0001) or eyes treated with Tdex (p=0.0434).

CONCLUSIONS

The ST formulation with xanthan gum demonstrated statistically superior anti-inflammatory and bactericidal properties as compared to Tdex.

LIMITATIONS

Variations in inoculation procedures produced limited eye-to-eye differences in the infection.

Simulating the migration of drifters deployed in the Bay of Biscay, during the Prestige crisis

A main conclusion following the oil spill from the Prestige tanker was that improvements in ocean circulation models were necessary; this was in order to predict, more accurately, the trajectories followed by the oil slicks and hence assist in fight against oil pollution operations. In this contribution, the results of the validation of a semi-empirical ocean circulation model, parameterised for the Bay of Biscay and forced with operational oceano-meteorological remote sensing observations, are shown. The model results have been validated with observations from drifting buoys, deployed in the Bay of Biscay during the crisis. The results show that the model explains a relatively large percentage of the current variability. The comparisons between the real and the estimated drifter trajectories indicate that for 3, 5 and 7 day-long trajectories, the drifter position is estimated with errors of approximately 23, 35 and 46km, respectively. The model reproduces relatively well the trajectory followed by the drifter with the shortest period (23 days).

Genetic impact of the Prestige oil spill in wild populations of a poor dispersal marine snail from intertidal rocky shores

In November 2002, the sinking of the Prestige cargo ship produced an oil spill of 60,000 tons that affected many areas along the Galician coast (in the northwest of Spain). In a number of rocky shore sites, most organisms (particularly marine mollusks) were nearly extinct at a local scale. We tested whether the local bottleneck/extinction that occurred in affected localities caused any detectable reduction of the genetic diversity in the marine snail Littorina saxatilis, an ovoviviparous rocky shore model species characterized by a low dispersal ability, high population density, and wide distribution range. We compared the level of genetic variation and population differentiation between affected (polluted) and control sites located in seven geographical areas (three sites per area, one impacted and two controls, and two replicates per site) one and a half years after the spill. The analysis included molecular marker variation (microsatellite and AFLP loci) and quantitative trait genetic variation for shell variables in embryos extracted from pregnant females. Our results indicate that the affected populations did not show a significant overall reduction in genetic diversity when compared to the controls, suggesting that the species is highly resistant to losing genetic variability as a consequence of a local short-term pollution process in spite of its low dispersal ability and direct development. However, some genetic effects were detected in the polluted populations, particularly for quantitative shell traits and AFLPs, consistent with local adaptations resulting from the fuel contamination.

PHYLOGENETIC EVIDENCE FOR MULTIPLE SYMPATRIC ECOLOGICAL DIVERSIFICATION IN A MARINE SNAIL

Parallel speciation can occur when traits determining reproductive isolation evolve independently in different populations that experience a similar range of environments. However, a common problem in studies of parallel evolution is to distinguish this hypothesis from an alternative one in which different ecotypes arose only once in allopatry and now share a sympatric scenario with substantial gene flow between them. Here we show that the combination of a phylogenetic approach with life-history data is able to disentangle both hypotheses in the case of the intertidal marine snail Littorina saxatilis on the rocky shores of Galicia in northwestern Spain. In this system, numerous phenotypic and genetic differences have evolved between two sympatric ecotypes spanning a sharp ecological gradient, and as aside effect of the former have produced partial reproductive isolation. A mitochondrial phylogeny of these populations strongly suggests that the two sympatric ecotypes have originated independently several times. Building upon earlier work demonstrating size-based assortative mating as the main contributor to reproductive isolation among ecotypes, our analysis provides strong evidence that divergent selection across a sharp ecological gradient promoted the parallel divergence of body size and shape between two sympatric ecotypes. Thus, divergent selection occurring independently in different populations has produced the marine equivalent of host races, which may represent the first step in speciation.

Polymorphism of the transmembrane region of the MICA gene and human brucellosis

We investigated the polymorphism of the transmembrane region of the MICA gene (major histocompatibility complex class I chain-related gene A) in relation to susceptibility to human brucellosis. We typed 114 patients with brucellosis and 121 healthy controls for MICA transmembrane polymorphism with polymerase chain reaction methods combined with fluorescent technology. We found a significant decrease in the frequency of the MICA-A4 allele in the patients with brucellosis compared with the controls (4.4% vs 10.3%, Pc = 0.03). The frequency of the MICA-A5 allele was increased in the group of patients with focal complications (15% vs 38%, Pc = 0.004). Our data suggest the MICA-A4 allele shows a tendency to be protective against infection by Brucella melitensis. Furthermore, the MICA-A5 allele appears to confer susceptibility to focal forms in patients with brucellosis.

Palliating the impact of fixation of a major gene on the genetic variation of artificially selected polygenes

Selective sweeps of variation caused by fixation of major genes may have a dramatic impact on the genetic gain from background polygenic variation, particularly in the genome regions closely linked to the major gene. The response to selection can be restrained because of the reduced selection intensity and the reduced effective population size caused by the increase in frequency of the major gene. In the context of a selected population where fixation of a known major gene is desired, the question arises as to which is the optimal path of increase in frequency of the gene so that the selective sweep of variation resulting from its fixation is minimized. Using basic theoretical arguments we propose a frequency path that maximizes simultaneously the effective population size applicable to the selected background and the selection intensity on the polygenic variation by minimizing the average squared selection intensity on the major gene over generations up to a given fixation time. We also propose the use of mating between carriers and non-carriers of the major gene, in order to promote the effective recombination between the major gene and its linked polygenic background. Using a locus-based computer simulation assuming different degrees of linkage, we show that the path proposed is more effective than a similar path recently published, and that the combination of the selection and mating methods provides an efficient way to palliate the negative effects of a selective sweep.

Estimation of the upper limit of the mutation rate and mean heterozygous effect of deleterious mutations

Deng et al. have recently proposed that estimates of an upper limit to the rate of spontaneous mutations and their average heterozygous effect can be obtained from the mean and variance of a given fitness trait in naturally segregating populations, provided that allele frequencies are maintained at the balance between mutation and selection. Using simulations they show that this estimation method generally has little bias and is very robust to violations of the mutation-selection balance assumption. Here I show that the particular parameters and models used in these simulations generally reduce the amount of bias that can occur with this estimation method. In particular, the assumption of a large mutation rate in the simulations always implies a low bias of estimates. In addition, the specific model of overdominance used to check the violation of the mutation-selection balance assumption is such that there is not a dramatic decline in mean fitness from overdominant mutations, again implying a low bias of estimates. The assumption of lower mutation rates and/or other models of balancing selection may imply considerably larger biases of the estimates, making the reliability of the proposed method highly questionable.

Change over time of bowel habit in irritable bowel syndrome: a prospective, observational, 1-year follow-up study (RITMO study)

BACKGROUND

Evolution of bowel habit in irritable bowel syndrome (IBS) is not well known.

AIM

To evaluate the change over time of bowel habit in IBS patients followed-up during 1 year.

METHODS

Five hundred and seventeen patients with IBS were prospectively included in an observational study with five evaluations over a 1-year period. Symptoms were recorded daily in diary cards during four 4-week periods along the study. Bristol Stool Scale (BSS) was used to define bowel habit.

RESULTS

Four-hundred patients completed the study. Rome II showed low-moderate agreement (42%) with BSS to define bowel habit. Frequency of constipation and diarrhoea showed little changes throughout the study. Over 50% of the patients had the same bowel habit when each diary was compared with the next one. A third of patients maintained the same habit throughout the study. Most changes occurred from/to mixed or unsubtyped IBS. Only 14% of cases changed from constipation to diarrhoea or vice versa. This change was associated to female gender (OR: 2.65).

CONCLUSIONS

The frequency of constipation and diarrhoea remains relatively stable over time. Changes in IBS subtypes are common, but changes between constipation and diarrhoea are rare. Alternating IBS is more frequent in women.

Analysis of the biases in the estimation of deleterious mutation parameters from natural populations at mutation–selection balance

Indirect estimates of the genomic rate of deleterious mutations (lambda), their average homozygous effect (s) and their degree of dominance (h) can be obtained from genetic parameters of natural populations, assuming that the frequencies of the loci controlling a given fitness trait are at mutation-selection equilibrium. In 1996, H.-W. Deng and M. Lynch developed a general methodology for obtaining these estimates from inbreeding/outbreeding experiments. The prediction of the sign and magnitude of the biases incurred by these estimators is essential for a correct interpretation of the empirical results. However, the assessment of these biases has been tested so far under a rather limited model of the distribution of dominance effects. In this paper, the application of this method to outbred populations is evaluated, focusing on the level of variation in h values (sigma(h)(2) and the magnitude of the negative correlation (rs,h) between s and h. It is shown that the method produces upwardly biased estimates of lambda and downwardly biased estimates of the average s in the reference situation where rs,h=0, particularly for large values of sigma(h)(2), and biases of different sign depending on the magnitude of the correlation. A modification of the method, substituting the estimates of the average h for alternative ones, allows estimates to be obtained with little or no bias for the case of rs,h=0, but is otherwise biased. Information on rs,h and sigma(h)(2), gathered from mutation-accumulation experiments, suggests that sigma(h)(2) may be rather large and rs,h is usually negative but not higher than about -0.2, although the data are scarce and noisy, and should be used with caution.

Tolerogenic response: Allorecognition pathways

The induction of immune tolerance in transplant recipients has been sought for many years but only a fundamental understanding of the immunological mechanisms underlying graft rejection will allow manipulation of the anti-graft immune response. In general, acute rejection is better understood and treated than chronic rejection, as they occur through partially different mechanisms. It is now generally accepted that recognition of same-species, non-self antigens (allorecognition) occurs through at least two different mechanisms, the direct and indirect pathways. In the direct pathway, donor MHC molecules on the surface of donor antigen-presenting cells (APCs) are recognised directly by the recipient's T cells. This mechanism is so immediate that it seems to be primarily involved in acute graft rejection. Since APCs of donor origin are depleted with time a second mechanism, the indirect pathway, takes over to cause chronic rejection, in which foreign MHC molecules are internalised, partially digested and presented as peptides to recipient T cells. Nonetheless, a number of studies are only fully understood when a third proposed allorecognition mechanism is taken into account. This is the semi-indirect pathway, as discussed in this short report.

Lead and cadmium in meat and meat products consumed by the population in Tenerife Island, Spain

The aim of this study was to determine the levels of lead and cadmium in chicken, pork, beef, lamb and turkey samples (both meat and meat products), collected in the island of Tenerife (Spain). Lead and cadmium were measured by graphite furnace atomic absorption spectrometry (GFAAS). Mean concentrations of lead and cadmium were 6.94 and 1.68 microg kg(-1) in chicken meat, 5.00 and 5.49 microg kg(-1) in pork meat, 1.91 and 1.90 microg kg(-1) in beef meat and 1.35 and 1.22 microg kg(-1) in lamb meat samples, respectively. Lead was below the detection limit in turkey samples and mean cadmium concentration was 5.49 microg kg(-1). Mean concentrations of lead and cadmium in chicken meat product samples were 3.16 and 4.15 microg kg(-1), 4.89 and 6.50 microg kg(-1) in pork meat product, 6.72 and 4.76 microg kg(-1) in beef meat product and 9.12 and 5.98 microg kg(-1) in turkey meat product samples, respectively. The percentage contribution of the two considered metals to provisional tolerable weekly intake (PTWI) was calculated for meat and meat products. Statistically significant differences were found for lead content in meats between the chicken and pork groups and the turkey and beef groups, whereas for cadmium concentrations in meats, significant differences were observed between the turkey and chicken, beef and lamb groups. In meat products, no clear differences were observed for lead and cadmium between the various groups.

[Molecular diagnosis of adult dominant polycystic kidney disease in the Canary Islands]

Adult dominant polycystic kidney disease is an hereditary condition responsible for 6% of end-stage renal failure in Spain. Two genes were located in chromosomes 16 and 4 as related to this age-dependent disease in the 90s (PKD1 and PKD2). The diagnosis can be easily achieved by sonographic study, but molecular analysis by means of linkage analysis has the advantage of an early diagnosis in asymptomatic genetic carriers, with a view to the preventive follow-up of these subjects and genetic counselling. In this paper we present the results of molecular analysis of 30 families with Adult Dominant Polycystic Kidney Disease (from the province of Las Palmas Spain), carried out linkage analysis with two series of microsatellite markers located within or in the vicinity ofPKD1 (D16S521, KG8, AC2.5, CW2, SM7) and PKD2 (D4S1538, D4S1534, D4S423,D4S414) genes. The objectives of the study were: first, to verify the informativeness, and therefore, the usefulness of these markers for family studies in our population; and second,to assess the sensitivity and specificity of the genetic analysis in our population. Most of the markers showed a high heterozygosity, comparable to data in other studies. Considering the alleles of the different markers together in a chromosome as an haplotype increased the informativeness of the markers, and allowed the unequivocal identification of genetic data in 97.7% of patients and 88.7% of healthy subjects. The sensitivity and specificity of the genetic analysis were 90.7% (CI 95%: 85.7-95.7) and 86.8% (CI 95%: 80.6-93.0), respectively.

Characterization and conservation of genetic diversity in subdivided populations

We review the available tools for analysing genetic diversity in conservation programmes of subdivided populations. Ways for establishing conservation priorities have been developed in the context of livestock populations, both from the classical population genetic analysis and from the more recent Weitzman's approach. We discuss different reasons to emphasize either within or between-population variation in conservation decisions and the methodology to establish some compromise. The comparison between neutral and quantitative variation is reviewed from both theoretical and empirical points of view, and the different procedures for the dynamic management of conserved subdivided populations are discussed.

Relaxation of selection with equalization of parental contributions in conservation programs: an experimental test with Drosophila melanogaster

Equalization of parental contributions is one of the most simple and widely recognized methods to maintain genetic diversity in conservation programs, as it halves the rate of increase in inbreeding and genetic drift. It has, however, the negative side effect of implying a reduced intensity of natural selection so that deleterious genes are less efficiently removed from the population with possible negative consequences on the reproductive capacity of the individuals. Theoretical results suggest that the lower fitness resulting from equalization of family sizes relative to that for free contribution schemes is expected to be substantial only for relatively large population sizes and after many generations. We present a long-term experiment with Drosophila melanogaster, comparing the fitness performance of lines maintained with equalization of contributions (EC) and others maintained with no management (NM), allowing for free matings and contributions from parents. Two (five) replicates of size N = 100 (20) individuals of each type of line were maintained for 38 generations. As expected, EC lines retained higher gene diversity and allelic richness for four microsatellite markers and a higher heritability for sternopleural bristle number. Measures of life-history traits, such as egg-to-adult viability, mating success, and global fitness declined with generations, but no significant differences were observed between EC and NM lines. Our results, therefore, provide no evidence to suggest that equalization of family sizes entails a disadvantage on the reproductive capacity of conserved populations in comparison with no management procedures, even after long periods of captivity.

Patterns of prescription of hypoglycaemic drugs in Gran Canaria (Canary Islands, Spain) and estimation of the prevalence of diabetes mellitus

OBJECTIVE

To study the patterns of hypoglycaemic treatment in our community and to estimate the prevalence of known and drug-treated diabetes mellitus.

METHODS

From all the diabetic patients who attended the Healthcare Centers of the National Health Service in Gran Canaria in 1999, a random sample of 2924 diabetic patients > 20 years old was selected. Data on age, gender, clinical onset of diabetes, and hypoglycaemic treatment were obtained. Data on drug consumption were supplied by the National Health Service.

RESULTS

Of the DM-2 patients 4.4% (3.65-5.14) 84.2% (82.7785.42), 9.4% (8.34-10.45) and 2.1% (1.58-2.61) received diet only, oral drugs, insulin or combination. The duration of DM-2 was associated with more oral drugs and more insulin treatment, but the duration of DM-1 was not associated with intensive insulin therapy;<50% of the type 1 patients had >or=3 daily injections. The prescriptions of biguanides were scarce; over 1/3 of them were of buformin. DM-1 and DM-2 patients were treated with similar doses of insulin, but DM-1 patients had more insulin injections (2.56 vs 2.07, P<0.001), and more fast-acting insulins (65.2% vs 38.0%, P<0.001). The estimated prevalences of known and drug-treated diabetes in the Gran Canaria island were 5.95% (95% CI: 5.096.80%) and 5.73% (4.88-6.57%).

CONCLUSIONS

Our prevalences of known and drug-treated diabetes is among the highest reported in European populations. The prescriptions of metformin and of combined therapy in DM-2, and of intensive insulin therapy in DM-1 are less frequent than expected, but nonetheless insulin therapy in DM-1 is more intensive and uses more fast-acting insulin than in DM-2.

The effect of antagonistic pleiotropy on the estimation of the average coefficient of dominance of deleterious mutations

We investigate the impact of antagonistic pleiotropy on the most widely used methods of estimation of the average coefficient of dominance of deleterious mutations from segregating populations. A proportion of the deleterious mutations affecting a given studied fitness component are assumed to have an advantageous effect on another one, generating overdominance on global fitness. Using diffusion approximations and transition matrix methods, we obtain the distribution of gene frequencies for nonpleiotropic and pleiotropic mutations in populations at the mutation-selection-drift balance. From these distributions we build homozygous and heterozygous chromosomes and assess the behavior of the estimators of dominance. A very small number of deleterious mutations with antagonistic pleiotropy produces substantial increases on the estimate of the average degree of dominance of mutations affecting the fitness component under study. For example, estimates are increased three- to fivefold when 2% of segregating loci are over-dominant for fitness. In contrast, strengthening pleiotropy, where pleiotropic effects are assumed to be also deleterious, has little effect on the estimates of the average degree of dominance, supporting previous results. The antagonistic pleiotropy model considered, applied under mutational parameters described in the literature, produces patterns for the distribution of chromosomal viabilities, levels of genetic variance, and homozygous mutation load generally consistent with those observed empirically for viability in Drosophila melanogaster.

Influence of exogenous insulin on C-peptide levels in subjects with type 2 diabetes

AIM

The aim of this study was to determine whether the influence of insulin therapy on fasting and stimulated C-peptide levels in type 2 diabetic subjects is due to plasma glucose reduction or a direct effect of exogenous insulin.

METHODS

Plasma glucose and serum C-peptide levels were determined before and after IV injection of 1mg glucagon on three separate days in 21 type 2 diabetic subjects. Day 1: without pharmacological treatment and fasting plasma glucose > 11.1 mmol/L; day 2: fasting plasma glucose 4.4-7.8 mmol/L, 1h after withdrawing intravenous regular insulin infusion; day 3: fasting plasma glucose 4.4-7.8 mmol/L with bed-time NPH insulin.

RESULTS

Fasting and glucagon stimulated C-peptide levels were higher on day 1 than days 2 and 3. Fasting, but not stimulated C-peptide levels, were lower on day 3 than day 2. These differences were not appeared when the percentage of C-peptide increment or the C-peptide/glucose ratio were compared in the three days.

CONCLUSIONS

Blood glucose reduction instead of exogenous insulin is responsible for the C-peptide decrease during insulin therapy in type 2 diabetic subjects.

Plasma Chemistry of NO in Complex Gas Mixtures Excited with a Surfatron Launcher

The plasma chemistry of NO has been investigated in gas mixtures with oxygen and/or hydrocarbon and Ar as carrier gas. Surface wave discharges operating at microwave frequencies have been used for this study. The different plasma reactions have been analyzed for a pressure range between 30 and 75 Torr. Differences in product concentration and/or reaction yields smaller than 10% were found as a function of this parameter. The following gas mixtures have been considered for investigation: Ar/NO, Ar/NO/O2, Ar/NO/CH4, Ar/CH4/O2, Ar/NO/CH4/O2. It is found that NO decomposes into N2 and O2, whereas other products such as CO, H2, and H2O are also formed when CH4 and O2 are present in the reaction mixture. Depending on the working conditions, other minority products such as HCN, CO2, and C2 or higher hydrocarbons have been also detected. The reaction of an Ar/NO plasma with deposits of solid carbon has also been studied. The experiments have provided useful information with respect to the possible removal of soot particles by this type of plasma. It has been shown that carbon deposits are progressively burned off by interaction with the plasma, and practically 100% decomposition of NO was found. Plasma intermediate species have been studied by optical emission spectroscopy (OES). Bands and/or peaks due to N2*, NO*, OH*, C2*, CN*, CH*, or H* were detected with different relative intensities depending on the gas mixture. From the analysis of both the reaction products and efficiency and the type of intermediate species detected by OES, different plasma reactions and processes are proposed to describe the plasma chemistry of NO in each particular mixture of gases. The results obtained provide interesting insights about the plasma removal of NO in real gas exhausts.

Genetic differentiation and estimation of effective population size and migration rates in two sympatric ecotypes of the marine snail Littorina saxatilis

On exposed rocky shores in Galicia (northwest Spain), a striking polymorphism exists between two ecotypes (RB and SU) of Littorina saxatilis that occupy different levels of the intertidal zone and exhibit an incomplete reproductive isolation. The setting has been suggested to represent ongoing sympatric speciation by ecological adaptation of the two ecotypes to their respective habitats. In this article we address whether or not the ecotypes have developed their own population structures in response to the rigors of their corresponding environments and life histories. We analyzed four to five allozymic loci from three surveys of the same sites, spanning a 14-year period. An experimental design including three localities with two transects per locality and three shore levels allowed studying temporal and spatial population structure and estimation of effective population sizes (N(e)), neighborhood sizes (N(n)), and migration rates (m). Genetic differentiation was significantly lower in RB populations (theta(ST) = 0.067) than in SU ones (theta(ST) = 0.124). Mean estimates of N(e), N(n), and m did not differ significantly between ecotypes, but local ecotype differences in migration between the two closest localities (larger migration rates in RB than in SU populations) could explain the pattern in population differentiation.

Pancreas Islet Transplantation in Patients With Type 1 Diabetes Mellitus After Kidney Transplantation

Diabetic patients with end-stage renal disease have a high mortality rate. A combined kidney-pancreas transplant is associated with greater life expectancy. Pancreas islet transplantation is an alternative involving a lower degree of morbidity. We present two patients, of 41 and 37 years of age, with a long history of diabetes mellitus (C-peptide negative), both with a previous kidney transplant, who had been treated with 22 and 28 U of insulin/d, respectively. Both patients had frequent episodes of unawareness hypoglycemia. Pancreatic islets were infused to a total of 7809 and 19,180 IE/kg, respectively. Basal posttransplant C peptide levels were 2.9 and 1.3 ng/mL. After the implant, one patient required occasional doses of insulin, and the other patient more than 50% reduced dose. After the first implant neither patient had any episodes of unawareness hypoglycemia. HbA1c at 4 months were 6.2% and 6.9%. There were no transplant-related complications.

XPS Study of Interface and Ligand Effects in Supported Cu2O and CuO Nanometric Particles

This paper reports an analysis of the changes in the photoemission parameters of copper in small particles of copper oxides deposited on silicon dioxide. This study is of relevance for investigations in the fields of heterogeneous catalysis and coordination chemistry. Copper oxides (Cu2O and CuO) have been deposited on the surface of a flat SiO2 substrate by evaporation of copper and subsequent oxidization of the deposited particles. XPS has been used to analyze the chemical and coordination state of copper. Large variations in the Cu 2p(3/2) binding energy (BE) and Auger parameter (alpha') have been found as a function of the type and amount of deposited copper oxide. The differences in BE calculated from the values of the lowest amount of deposited material and those of the bulk compounds were -0.4 eV (Cu2O) and -1.9 eV (CuO), while those in alpha' amounted to 2.9 (Cu2O) and 1.6 eV (CuO). The observed changes have been described in terms of the chemical state vector (CSV) concept in a Wagner plot and rationalized by considering the characteristics of bonding and electronic interactions that occur at a given oxide/oxide interface. These interactions have been modeled by means of quantum mechanical calculations with cluster models simulating the Cu-O-Si bonding at the interface. The effect of the polarization of the surrounding media around the copper cations has been also estimated for both the dispersed clusters supported on the SiO2 substrate and for the copper oxide materials in bulk form. A change in the values of alpha' and BE of copper (ie., delta alpha' = 1.1 eV, deltaBE = 0.1 eV) upon adsorption on the Cu+ species of Cu2O moieties dispersed on SiO2 of a phenyl-acetylene molecule illustrates the use of XPS to study the formation of cation-ligand complexes in heterogeneous systems. A detailed description of the bonding interactions of these coordinated Cu+ species in terms of initial and final state effects of the photoemission process has been also carried out by means of quantum mechanical calculations and cluster models.