Partial-solubility Parameters of Naproxen and Sodium Diclofenac

The expanded Hansen method was tested for determination of the solubility parameters of two non-steroidal anti-inflammatory drugs, naproxen and sodium diclofenac. This work describes for the first time the application of the method to the sodium salt of a drug. The original dependent variable of the expanded Hansen method, involving the activity coefficient of the drug, was compared with the direct use of the logarithm of the mole fraction solubility lnX₂ in the solubility models. The solubility of both drugs was measured in pure solvents of several chemical classes and the activity coefficient was obtained from the molar heat and the temperature of fusion. Differential scanning calorimetry was performed on the original powder and on the solid phase after equilibration with the pure solvents, enabling detection of possible changes of the thermal properties of the solid phase that might change the value of the activity coefficient. The molar heat and temperature of fusion of sodium diclofenac could not be determined because this drug decomposed near the fusion temperature. The best results for both drugs were obtained with the dependent variable lnX₂ in association with the four-parameter model which includes the acidic and basic partial-solubility parameters δ_a and δ_b instead of the Hansen hydrogen bonding parameter δ_h. Because the dispersion parameter does not vary greatly from one drug to another, the variation of solubility among solvents is largely a result of the dipolar and hydrogen-bonding parameters, a fact that is being consistently found for other drugs of small molecular weight. These results support earlier findings with citric acid and paracetamol that the expanded Hansen approach is suitable for determining partial-solubility parameters. The modification introduced in the expanded Hansen method, i.e. the use of lnX₂ as the dependent variable, provides better results than the activity coefficient used in the original method. This is advantageous for drugs such as sodium diclofenac for which the ideal solubility cannot be estimated. This paper shows for the first time that the method is suitable for determination of the partial-solubility parameters of a sodium salt of a drug, sodium diclofenac.     

Phage types and genotypes of shiga toxin-producing Escherichia coli O157:H7 isolates from humans and animals in spain: identification and characterization of two predominating phage types (PT2 and PT8)

Phage typing and DNA macrorestriction fragment analysis by pulsed-field electrophoresis (PFGE) were used for the epidemiological subtyping of a collection of Shiga toxin-producing Escherichia coli (STEC) O157:H7 strains isolated in Spain between 1980 and 1999. Phage typing distinguished a total of 18 phage types among 171 strains isolated from different sources (67 humans, 82 bovines, 12 ovines, and 10 beef products). However, five phage types, phage type 2 (PT2; 42 strains), PT8 (33 strains), PT14 (14 strains), PT21/28 (11 strains), and PT54 (16 strains), accounted for 68% of the study isolates. PT2 and PT8 were the most frequently found among strains from both humans (51%) and bovines (46%). Interestingly, we detected a significant association between PT2 and PT14 and the presence of acute pathologies. A group of 108 of the 171 strains were analyzed by PFGE, and 53 distinct XbaI macrorestriction patterns were identified, with 38 strains exhibiting unique PFGE patterns. In contrast, phage typing identified 15 different phage types. A total of 66 phage type-PFGE subtype combinations were identified among the 108 strains. PFGE subtyping differentiated between unrelated strains that exhibited the same phage type. The most common phage type-PFGE pattern combinations were PT2-PFGE type 1 (1 human and 11 bovine strains), PT8-PFGE type 8 (2 human, 6 bovine, and 1 beef product strains), PT2-PFGE subtype 4A (1 human, 3 bovine, and 1 beef product strains). Nine (29%) of 31 human strains showed phage type-PFGE pattern combinations that were detected among the bovine strains included in this study, and 26 (38%) of 68 bovine strains produced phage type-PFGE pattern combinations observed among human strains included in this study, confirming that cattle are a major reservoir of strains pathogenic for humans. PT2 and PT8 strains formed two groups which differed from each other in their motilities, stx genotypes, PFGE patterns, and the severity of the illnesses that they caused.     

Digoxin dosing in the aged: new pharmacokinetic system versus Jellife and Koup methods

To evaluate three methods for digoxin dose adjustment in aged patients, we determined the plasma digoxin levels that would be attained in 87 aged patients with doses adjusted to the kidney function by means of three separate procedures. Mean patient age was: 79.0 +/- 6.3 years; creatinine clearance (Clc): 0.70 +/- 0.23 mL/Kg of lean body weight and minute; digoxinemia/dose ratio (RCpD): 0.421 +/- 0.237 Kg/L. The dose that would attain a digoxinemia of 1.2 ng/mL, calculating the elimination constant (K) and the volume of distribution (V) as linear functions of the Clc, so that K ranges between 0.173 and 0.462 days-1 and V between 4 and 10 L/Kg of lean body weight when the Clc varies from 0 to 110 mL/minute, was 2947 ng/Kg of lean body weight, coefficient of variation (CV): 25.2%. The digoxinemia that patients would have with this D, taking into account the individual RCpD, was 1.1 ng/mL, CV: 38.0%; with figures between 0.8 y 2.0 ng/mL and above 2.0 ng/mL in the 81.6% and the 0.0% of the patients (95% confidence intervals (95% CI): 72.2% to 88.4 and 0.0% to 4.6%), respectively. The precision and the bias were 0.43 and -0.06 ng/mL (95% CI: 0.38 to 0.48 and -0.16 to 0.03 ng/mL), respectively, and with this method the digoxinemia was not associated with the Clc. We concluded that the described method would lead to good results if digoxin has not been prescribed in order to control the cardiac frequency in the setting of auricular fibrilation.     

Enteropathogenic Escherichia coli strains carrying genes encoding the PER-2 and TEM-116 extended-spectrum beta-lactamases isolated from children with diarrhea in Uruguay

We studied 13 extended-spectrum beta-lactamase (ESBL)-producing enteropathogenic Escherichia coli isolates from children suffering acute diarrhea in Uruguay. ESBL characterization in crude extracts showed a single band at pI 5.4. PCR amplification and sequencing data allowed identification of blaPER-2 and blaTEM-116. Retrospective analysis suggests that these strains were disseminated in the community, even if unnoticed, prior to their access to the hospital environment more than a decade ago.     

Virilizing mature ovarian cystic teratomas

 Three further cases of mature benign cystic teratomas of the ovary associated with virilization are added to the three previously reported in the literature. They were found in postmenopausal, obese, diabetic women aged 52, 61, and 67 years. The patients presented with hirsutism and voice changes and clitoromegaly was present in one. Testosterone and androstenedione levels were elevated but promptly regressed after removal of the tumours. Histologically, sheets of stromal luteinized cells were found peripherally at the interface between the neoplasm and ovarian tissue. Luteinization of ovarian stroma induced by an unknown factor related to diabetes mellitus is the origin of the virilization. Received: 8 January 1997 / Accepted: 28 February 1997     

High resolution quantitative EEG analysis

Summary High resolution spectral methods are explored as an alternative to broad band spectral parameters (BBSP) in quantitative EEG analysis. In a previous paper (Valdes et al. 1990b) regression equations (Developmental surfaces) were introduced to characterize the age-frequency distribution of the mean and standard deviation of the log spectral EEG power in a normative sample. These normative surfaces allow the calculation of z transformed spectra for all derivations of the 10/20 system and z maps for each frequency. Clinical material is presented that illustrates how these procedures may pinpoint frequencies of abnormal brain activity and their topographic distribution, avoiding the frequency and spatial smearing that may occur using BBSP. The increased diagnostic accuracy of high resolution spectral methods is demonstrated by means of receiver operator characteristic (ROC) curve analysis. Procedures are introduced to avoid type I error inflation due to the use of more variables in this type of procedure.     

HLA allele and haplotype frequencies in Algerians : Relatedness to Spaniards and Basques

The powerful genetic polymorphism of the HLA system has been used to identify individuals and populations. Ethnic groups may be characterized by specific HLA allele frequencies and particular extended HLA haplotypes; also, genetic relationships among these groups may be deduced. In the present study, serology and DNA typing were used to detect HLA-A, -B, -C, -DR, and -DQ alleles in each individual and to calculae characteristic haplotypes in Algerians. These results were compared to those previously obtained in other populations, particularly northern Mediterraneans; genetic distances and their respective dendrograms place Basques and Spaniards closer to Algerians than to other Europeans. Also, characteristic Basque and/or Spanish haplotypes are found in Algerians; i.e., A30-B18-Cw3-DR3-DQ2 and Al-B57-Ctv7-DR7-DQ2. This supports the evidence that the Algerian population, mainly its paleo-North African component (Berbers), has a common descent with Basques and Spaniards, probably reflecting a preneolithic relationship between Iberians and paleo-North Africans.     

Demonstration of an inwardly rectifying K+ current component modulated by thyrotropin-releasing hormone and caffeine in GH3 rat anterior pituitary cells

 Reduction of an inwardly rectifying K⁺ current by thyrotropin-releasing hormone (TRH) and caffeine has been considered to be an important determinant of electrical activity increases in GH₃ rat anterior pituitary cells. However, the existence of an inwardly rectifying K⁺ current component was recently regarded as a misidentification of an M-like outward current, proposed to be the TRH target in pituitary cells, including GH₃ cells. In this report, an inwardly rectifying component of K⁺ current is indeed demonstrated in perforated-patch voltage-clamped GH₃ cells. The degree of rectification varied from cell to cell, but both TRH and caffeine specifically blocked a fraction of current with strong rectification in the hyperpolarizing direction. Use of ramp pulses to continuously modify the membrane potential demonstrated a prominent blockade even in cells with no current reduction at voltages at which M-currents are active. Depolarization steps to positive voltages at the maximum of the inward current induced a caffeine-sensitive instantaneous outward current followed by a single exponential decay. The magnitude of this current was modified in a biphasic way according to the duration of the previous hyperpolarization step. The kinetic characteristics of the current are compatible with the possibility that removal from inactivation of a fast-inactivating delayed rectifier causes the hyperpolarization-induced current. Furthermore, the inwardly rectifying current was blocked by astemizole, a potent and selective inhibitor of human ether-á-go-go -related gene (HERG) K⁺ channels. Along with other pharmacological and kinetic evidence, this indicates that the secretagogue-regulated current is probably mediated by a HERG-like K⁺ channel. Addition of astemizole to current-clamped cells induced clear increases in the frequency of action potential production. Thus, an inwardly-rectifying K⁺ current and not an M-like outward current seems to be involved in TRH and caffeine modulation of electrical activity in GH₃ cells. Received: 15 May 1997 / Received after revision and accepted: 24 July 1997     

Brain potentials reflect residual face processing in a case of prosopagnosia

Here, ERPs were employed to characterise the residual face processing of FE, a patient with extensive damage to the ventral temporal-occipital cortex and a dense prosopagnosia. Alarge N170 was present in FE and he performed well in tests of face structural processing. Covert recognition of the faces of personal acquaintances was demonstrated with P300 oddball experiments. The onset latency of the P300 effect was normal, indicating fast availability of covert memory. The scalp topography of this component in FE was different from that of the P3b, presenting a centro-frontal maximum. FE also presented larger skin conductance responses to familiar than to unfamiliar faces. The amplitudes of both the single-trial P300s and the SCRs triggered by familiar faces were positively correlated with the degree of person-familiarity that FE had for the poser. He performed at chance when asked to select between the face of a familiar person and that of an unfamiliar person on the basis of explicit recognition, whereas he selected more the previously known face if the forced choice was based on trustworthiness or a vague sense of familiarity. The results suggest that in FE, early face processing was relatively intact and covert recognition was fast. Neural structures involved in the processing of emotional or social cues possibly mediate the covert recognition present in FE.     

Antimicrobial resistance of Shiga toxin (verotoxin)-producing Escherichia coli O157:H7 and non-O157 strains isolated from humans, cattle, sheep and food in Spain

A total of 722 Shiga toxin-producing Escherichia coli (STEC) isolates recovered from humans, cattle, ovines and food during the period from 1992 to 1999 in Spain were examined to determine antimicrobial resistance profiles and their association with serotypes, phage types and virulence genes. Fifty-eight (41%) out of 141 STEC O157:H7 strains and 240 (41%) out of 581 non-O157 STEC strains showed resistance to at least one of the 26 antimicrobial agents tested. STEC O157:H7 showed a higher percentage of resistant strains recovered from bovine (53%) and beef meat (57%) than from human (23%) and ovine (20%) sources, whereas the highest prevalence of antimicrobial resistance in non-O157 STEC was found among isolates recovered from beef meat (55%) and human patients (47%). Sulfisoxazole (36%) had the most common antimicrobial resistance, followed by tetracycline (32%), streptomycin (29%), ampicillin (10%), trimethoprim (8%), cotrimoxazole (8%), chloramphenicol (7%), kanamycin (7%), piperacillin (6%), and neomycin (5%). The multiple resistance pattern most often observed was that of streptomycin, sulfisoxazole, and tetracycline. Ten (7%) STEC O157:H7 and 71 (12%) non-O157 strains were resistant to five or more antimicrobial agents. Most strains showing resistance to five or more antimicrobial agents belonged to serotypes O4:H4 (4 strains), O8:H21 (3 strains), O20:H19 (6 strains), O26:H11 (8 strains eae-beta1), O111:H- (3 strains eae-gamma2), O118:H- (2 strains eae-beta1), O118:H16 (5 strains eae-beta1), O128:H- (2 strains), O145:H8 or O145:H- (2 strains eae-gamma1), O157:H7 (10 strains eae-gamma1), O171:H25 (3 strains), O177:H11 (5 strains eae-beta1), ONT:H- (3 strains/1 eae-beta1) and ONT:H21 (2 strains). Interestingly, most of these serotypes, i.e., those indicated in bold) were found among human STEC strains isolated from patients with hemolytic uremic-syndrome (HUS) reported in previous studies. We also detected, among non-O157 strains, an association between a higher level of multiple resistance to antibiotics and the presence of the virulence genes eae and stx(1). Moreover, STEC O157:H7, showed an association between certain phage types, PT21/28 (90%), PT23 (75%), PT34 (75%), and PT2 (54%), with a higher number of resistant strains. We conclude that the high prevalence of antimicrobial resistance detected in our study is a source of concern, and cautious use of antibiotics in animals is highly recommended.