Acute and long-term humoral immunity following active immunization of rabbits with inacctivated spores of various Encephalitozoon species

Microsporidia of the genus Encephalitozoon are increasingly being reported as a cause of severe, often disseminated infections, mainly in patients with acquired immunodeficiency syndrome (AIDS). Immunological identification of each of the three recognized species (E. cuniculi, E. hellem, and E. intestinalis) requires the availability of specific immune sera. All sera available thus far have been generated by direct inoculation of rabbits with virulent microsporidian spores. This study demonstrates for the first time that subcutaneous immunization with inactivated spores of E. cuniculi, E. hellem, or E. intestinalis is capable of generating highly active rabbit hyperimmune sera to the homologous antigens, with maximal titers being 1:5,120, 1:1,280, and 1:2,560, respectively, as determined by the indirect immunofluorescence technique (IIF). Broad cross-reactivity of the rabbit antisera with all heterologous Encephalitozoon antigens was determined by IIF and immunogold electron microscopy; however, only the E. hellem immune serum strongly cross-reacted with spores of Enterocytozoon bieneusi. During the 35-month follow-up period the antibody titers to the homologous antigens declined to 1:640, 1:160, and 1:320, respectively. The observed decay curves for antibody titers against E. cuniculi, E. hellem, and E. intestinalis were fitted using mathematical modeling, resulting in a predicted duration for specific immune responses of about 7 years on average. Knowledge of the magnitude and duration of specific immune responses is a prerequisite for further evaluation of the concept of using inactivated microsporidian spores in the quest for vaccines against microsporidian infections. Received: 10 April 2000 / Accepted: 18 July 2000     

Staphylococcus aureus carriage among GPs in the Netherlands

Background

The extent to which GPs serve as a reservoir for antibiotic-resistant Staphylococcus aureus is unknown and not well studied.

Aim

To determine the prevalence of nasal S. aureus carriage among GPs in the Netherlands, as well as the antimicrobial resistance and the genotypes of isolated S. aureus.

Design of study

Observational, point-prevalence, and cross-sectional study.

Setting

GPs attending the annual conference of the Dutch College of General Practitioners in 2006.

Method

Nasal swabs were randomly taken from 395 GPs and analysed for the presence of S. aureus. Antimicrobial susceptibility was determined by a microbroth dilution method and the genotypes by spa typing, which was associated with multilocus sequence typing.

Results

Of the GPs, 129/395 (33%; 95% confidence interval [CI] = 28 to 37%) were carriers of S. aureus. No meticillin-resistant S. aureus (MRSA) was found. Resistance was observed to penicillin (71%; 95% CI = 63 to 79%), fusidic acid (7%; 95% CI = 3 to 13%), and clarithromycin (6%; 95% CI = 3 to 12%). In 72% of the isolates, an MRSA-related genotype of S. aureus was found.

Conclusion

The low antibiotic resistance found among S. aureus of GPs suggests that GPs are not a reservoir of antibiotic-resistant S. aureus strains. The relatively high resistance to fusidic acid, which has not previously been described in the Netherlands and is mostly because of antibiotic use, suggests that patients infect GPs and not the other way round. GPs may be at risk for nasal carriage of S. aureus with an MRSA-related genotype.     

Another observation with VATER association and a complex IV respiratory chain deficiency

The VATER association of vertebral anomalies (V), anal atresia (A), esophageal atresia and/or tracheo-esophageal fistula (TE), radial and renal anomalies (R) is a common congenital association of unknown origin with probably heterogeneous causes. Here, we report on a girl presenting with pre- and postnatal growth retardation, esophageal atresia, vertebral and costal anomalies and a unilateral radial defect, consistent with the diagnosis of VATER association. In the first month of life, she presented with failure to thrive, severe episodes of hypoglycemia, liver dysfunction and high levels of lactate, which prompted us to perform metabolic screening. A complex IV respiratory chain deficiency (RCD) was diagnosed on a liver biopsy. The respiratory chain defect was not observed in skin fibroblasts. No mtDNA point mutation or deletion was identified. The girl is now 9 years old and has a normal mental development but persistent feeding difficulties and moderate hyperlactatemia. To our knowledge, this is the second report of VATER association with mitochondrial disorder. In a previous report, a VACTERL association was observed in a girl with the mitochondrial A3243G point mutation. The association of VATER phenotype with a mitochondrial disorder may be coincidental but could also suggest that the presence of multiple malformations is the result of the antenatal expression of RCD.     

Toward experimental assessment of receptor occupancy: TGN1412 revisited

In March 2006, 6 healthy volunteers experienced serious adverse reactions during a first-in-human clinical trial of the superagonistic anti-CD28 mAb TGN1412. A first investigation excluded contaminations of the drug product or protocol irregularities as the root cause. Later, an expert scientific group convened in the United Kingdom to develop recommendations pertinent to minimizing risks of first-in-human clinical trials. The expert scientific group concluded from in silico calculations that at the initial dose of 0.1 mg/kg, which was adjusted on the basis of the no observed adverse effect level, approximately 86.2% to 90.9% CD28 receptor occupancy was obtained. Here we developed a flow cytometric method that revealed receptor occupancy of approximately 45% to 80% under the above conditions. Thus we present a method to experimentally determine receptor occupancy that can be taken as one parameter to define the minimal anticipated biological effect level as the basis for calculating safer starting doses for first-in-human clinical trials for products in which a potential risk has been identified. Additional measures are being discussed that will help to significantly improve safety of first-in-human clinical trials.     

Early cleavage predicts the viability of human embryos in elective single embryo transfer procedures

BACKGROUND: The reduction of multiple pregnancies by using elective single embryo transfers (eSET) requires critical and careful selection of the embryo for transfer. The current study was undertaken to assess whether early cleavage could be used as a marker of embryo competence in eSET procedures. METHODS: The study included analysis of 178 eSET procedures. All embryos were checked for early cleavage at 25-27 h post insemination or ICSI. The embryos that possessed two cells at 25-27 h post insemination or ICSI were designated as 'early cleavage' (EC) embryos and those that had not yet cleaved were classified as 'no early cleavage' (NEC) embryos. Selection of the embryo for transfer was based on embryo morphology and growth rate on day 2 and not early cleavage. Clinical parameters were compared between 72 EC and 106 NEC single embryo transfers. RESULTS: A significantly higher clinical pregnancy rate was observed after transfer of EC (50%) than NEC (26.4%) embryos. CONCLUSIONS: The current study provides compelling evidence that EC embryos possess significantly higher developmental competence than NEC embryos.