A soluble inorganic pyrophosphatase from the cattle tick Rhipicephalus microplus capable of hydrolysing polyphosphates

Polyphosphates have been found in all cell types examined to date and play diverse roles depending on the cell type. In eukaryotic organisms, polyphosphates have been investigated mainly in mammalian cells, and only a few studies have addressed arthropods. Pyrophosphatases have been shown to regulate polyphosphate metabolism. However, these studies were restricted to trypanosomatids. Here we focus on the tick Rhipicephalus microplus, a haematophagous ectoparasite that is highly harmful to cattle. We produced a recombinant R. microplus pyrophosphatase (rRmPPase) with the aim of investigating its kinetic parameters using polyphosphates as substrate. Molecular docking assays of RmPPase with polyphosphates were also carried out. The kinetic and Hill coefficient parameters indicated that rRmPPase has a greater affinity, higher catalytic efficiency and increased cooperativity for sodium phosphate glass type 15 (polyP₁₅ ) than for sodium tripolyphosphate (polyP₃ ). Through molecular docking, we found that polyP₃ binds close to the Mg²⁺ atoms in the catalytic region of the protein, participating in their coordination network, whereas polyP₁₅ interactions involve negatively charged phosphate groups and basic amino acid residues, such as Lys56, Arg58 and Lys193; polyP₁₅ has a more favourable theoretical binding affinity than polyP₃ , thus supporting the kinetic data. This study shows, for the first time in arthropods, a pyrophosphatase with polyphosphatase activity, suggesting its participation in polyphosphate metabolism.

Neural fraud detection in credit card operations

This paper presents an online system for fraud detection of credit card operations based on a neural classifier. Since it is installed in a transactional hub for operation distribution, and not on a card-issuing institution, it acts solely on the information of the operation to be rated and of its immediate previous history, and not on historic databases of past cardholder activities. Among the main characteristics of credit card traffic are the great imbalance between proper and fraudulent operations, and a great degree of mixing between both. To ensure proper model construction, a nonlinear version of Fisher's discriminant analysis, which adequately separates a good proportion of fraudulent operations away from other closer to normal traffic, has been used. The system is fully operational and currently handles more than 12 million operations per year with very satisfactory results.

[Migrant populations at the Hôpital de l'Enfance of Lausanne (HEL): evaluation inquiry, taking care and contribution of cultural mediators-translators]

The number of patients belonging to migrant populations who consult Lausanne's Hôpital de l'Enfance (HEL) has increased massively in an exponential manner. HEL is a facility dedicated to children with a vocation of public health and training in a university setting and it has to make a point of developing an adequate and pertinent health care system for these populations. In order to do this, a study was undertaken in the form of a prospective survey including over a thousand ambulatory patients. Administrative data (origin, date of migration, nature of the permit and legal situation), social data (home language, professional situation, number of siblings), medical (diagnosis) and psychosomatic data (sleep, enuresis) was recorded as well as data testing the level of understanding between carrier and patient. The study allowed us to define priorities of intervention: introduction of a service of translators--cultural mediators trained by the association "Appartenances" (as well as on going follow-up and assessment of this service), training of health care workers in the fields of cultural mediation and the different aspects of migrant population medicine and, finally, the creation of a steering group within the Institution. Having allowed rapid and spectacular improvement in the quality of the service provided by the HEL, this process is also included in the will to improve health care given to migrant populations at local and national levels in accordance with the priorities defined by the WHO in this domain. It is this experience which is reported in this paper.

Microbial keratitis resulting in loss of the eye

BACKGROUND AND OBJECTIVES

The purpose of this study was to determine the clinical characteristics of infected corneal ulcers resulting in loss of the eye.

PATIENTS AND METHODS

The authors conducted a retrospective study of all cases requiring evisceration or enucleation due to microbial keratitis at Wills Eye Hospital between January 1, 1989, and December 31, 1995. Medical records were reviewed to determine the past medical and ophthalmic history, duration of symptoms and treatment prior to referral, and the size of the ulcer at time of presentation. Treatment, culture results, and clinical course were also analyzed.

RESULTS

During the study period, 1.8% (17 of 965) of the patients with corneal ulcers admitted to Wills Eye Hospital underwent evisceration or enucleation for microbial keratitis. The median age of the patients was 67 years (+/- 20.1 years). A majority of the patients (82%, 14 of 17) had a history of preexisting ocular disease resulting in poor visual acuity. The median duration of symptoms prior to presentation to Wills Eye Hospital was 11.4 days (+/- 13.9 days). The average size of the corneal infiltrate was 40.8 mm2 (+/- 38.7 mm2). The most common pathogens were Pseudomonas (7 cases) and Streptococcus (3 cases). Patients required evisceration (14 cases) or enucleation (3 cases) due to uncontrolled infection.

CONCLUSIONS

Microbial keratitis resulting in loss of the eye occurred typically in patients who were elderly with preexisting poor visual acuity, who presented with severe infections due to virulent organisms or delayed treatment.

The effect of vitamin E on erythrocyte hemolysis and lipid peroxidation in newborn premature infants

The biochemical effect of vitamin E supplementation to mothers with threatened premature delivery and to premature infants after birth has been studied. Although a weak correlation was found between maternal and cord blood vitamin E levels at birth, cord blood levels were not significantly higher in the infants from supplemented mothers than those from unsupplemented mothers. Furthermore, maternal vitamin E treatment did not prevent either erythrocyte hemolysis or lipid peroxide formation in the premature infants after birth. On the other hand, intramuscular vitamin E to infants after birth produced a marked biochemical effect, with both zero erythrocyte hemolysis and low lipid peroxide formation when serum vitamin E increased above 2 mg/100 ml. We conclude that intramuscular vitamin E immediately after birth is necessary to achieve a biochemical effect of vitamin E in the early neonatal period. (No cases of retrolental fibroplasia occurred in the present study.)