European Sero-Epidemiology Network: standardisation of the assay results for pertussis

A standardisation process was developed in order to compare and harmonize serological results of pertussis toxin (PT) antibody measurements performed by laboratories using different technical procedures for detection. This involved the development of a common panel, of sera by a designed reference centre, the distribution of the panel to each participating laboratory for testing with their routine methods, the comparison of the obtained results to those of the reference centre, and the calculation of standardisation equations by regressing the quantitative results against those of the reference centre. As a cut-off indicative of protection against pertussis has not yet been defined, a particular emphasis was laid upon achieving standardisation of high titre results that would allow epidemiological evaluations based on the estimation of the incidence of recent infections rather than on the traditional approach of determining the population immunity profile. A generally good agreement was achieved between the participating laboratories, all using ELISA procedures very similar in many crucial aspects, and standardisation equations were produced useful to enable inter-country comparison during the next stages of the European Sero-Epidemiology Network (ESEN) project concerning the serological surveillance of immunity to pertussis in Europe.     

Leukotriene production by fresh human bone marrow cells: evidence of altered lipoxygenase activity in chronic myelocytic leukemia

The metabolism of arachidonic acid through the lipoxygenase pathway was studied in suspensions of fresh human bone marrow cells from eight patients with chronic myelocytic leukemia (CML) and 10 normal controls. After the cells were incubated with the calcium ionophore A23187 and arachidonic acid, a technique including reverse- and straight-phase high-pressure liquid chromatography (HPLC) was employed to isolate and detect different lipoxygenase-mediated compounds. The detected compounds included leukotriene B4 (LTB4), with its two major nonenzymatic isomers 6-trans-LTB4 and 12-epi-6-trans-LTB4 5S,12S-DHETE, and the monohydroxy eicosatetraenoic acids 5-HETE, 12-HETE, and 15-HETE. The pattern of lipoxygenase-mediated products from the bone marrows was similar to that previously described from human peripheral blood. Of eight bone marrow samples from CML patients, five expressed values above 600 ng LTB4/10(8) nucleated cells, as compared to only one out of 10 controls. In contrast, the CML patients produced significantly lower amounts of both the double-dioxygenation product 5S,12S-DHETE (56.8 +/- 16.0 ng [mean +/- SE] versus 146.1 +/- 31.3 ng; p less than 0.05) and the monohydroxy acid 12-HETE (965 +/- 351 ng versus 4390 +/- 1801 ng; p less than 0.05), indicating a 12-lipoxygenase deficiency. The present results show that leukotrienes are formed by human bone marrow cells and further suggest the existence of altered lipoxygenase activity in CML.     

Validation of nested Bordetella PCR in pertussis vaccine trial.

A nested PCR, using a 239-bp sequence in the pertussis toxin promoter region, was developed and evaluated. The assay differentiates Bordetella pertussis, Bordetella parapertussis, and Bordetella bronchiseptica by restriction enzyme analysis of the amplified fragments. The diagnostic performance of the PCR was evaluated in a Swedish pertussis vaccine efficacy trial which took place from 1992 to 1995, including study children and household members and using culture and serology for laboratory confirmation of suspected cases. In total 2,421 nasopharyngeal aspirates were analyzed. The total diagnostic sensitivity for B. pertussis was 90.2% (194 of 215). During the study period samples were processed with and without the cation-exchange resin Chelex. The PCR diagnostic sensitivity for B. pertussis among the Chelex-treated aspirates was 94.9% (75 of 79), and that for B. pertussis among 124 aspirates in a consecutive non-Chelex-treated material was 89.5% (111 of 124). After Chelex treatment of the 13 PCR-negative samples, an additional six became PCR positive, giving a final sensitivity of 94.3%. In addition, PCR was positive for B. pertussis with 57 of 1,744 samples negative by culture but with available serological data. The specificity of PCR with these samples was supported by a significant increase in antibody levels between acute and convalescent sera in 45 cases and by epidemiological or clinical data in all but two of the remaining cases. PCR was also positive for B. pertussis with 26 of 415 aspirates from episodes lacking serology. The diagnostic sensitivity of PCR for B. parapertussis was 74.0% (37 of 50). There were an additional seven culture-negative B. parapertussis PCR findings, six from cases with significant antibody increases against filamentous hemagglutinin only and one from a case lacking serology. There were no samples positive for B. bronchiseptica. In conclusion, PCR detection of B. pertussis and/or B. parapertussis enabled us to identify 90 positive nasopharyngeal aspirates, in addition to the 262 culture-positive samples (an increase of 34%). Relating these cases to serology and clinical data indicated a PCR specificity approaching 100%.     

Immunomagnetic separation and solid-phase detection of Bordetella pertussis.

In the present study, novel solid-phase methods were used for both sample preparation and PCR detection of Bordetella pertussis. The sample preparation was performed by immunomagnetic separation with paramagnetic beads coated with polyclonal antibodies directed toward the surface antigens of the bacteria. The precoated immunobeads were directly used on nasopharyngeal aspirates to capture the bacteria on the solid support and were subsequently transferred to the PCR tube with no further manipulations. The region encompassing the pertussis toxin promoter was analyzed to allow direct discrimination between the three major Bordetella species (B. pertussis, B. parapertussis, and B. bronchiseptica). The resulting amplicons were captured on a second magnetic solid phase, allowing detection and restriction analysis of the target sequence. A colorimetric detection system based on a DNA binding fusion protein enabled the use of standardized enzyme-linked immunosorbent format tests both for the detection of Bordetella spp. and for species evaluation. When the optimized system was evaluated on 55 clinical aspirate samples, 21 of 22 (95%) culture-positive samples were positive by the system that we developed. In addition, two samples were positive by the PCR-based assay, while the culture assay was negative. The implications of these results are discussed.     

Immunomodulating properties of bestatin in cancer patients. A phase II trial

Thirty-four patients with cancer (30) or ARC (4) with severe T cell defect or imbalance persisting a long time after completion of any cytostatic treatment were treated by bestatin 30 mg/day 3 days per week during three weeks. The drug has no toxicity of any kind. Reassessment of T cell subsets after completion of bestatin therapy showed a significant improvement of the absolute number of CD4 cells in peripheral blood. CD8 subsets wether initially increased or decreased were modified towards normalisation but the modification reached statistical significance only in the subgroup with initial absolute defect of CD8 cells. CD4/CD8 ratio was significantly increased whether considering all cycles of therapy, or all those given to patients with initially high or normal CD8 subsets. Bestatin appears to have immunomodulating properties which might be useful in cancer patients.     

Hereditary Ring Sideroblastic Anaemia and Christmas Disease in a Swedish Family

The association of hereditary ring sideroblastic anaemia with Christmas disease in a Swedish family is described. We have studied the transmission of the sideroblastic trait, in relation to HLA groups and Christmas disease, and also evaluated the erythrocyte morphology, uroporphyrinogen-I-synthetase activity and S-ferritin for the detection of latent cases of ring sideroblastic anaemia. The proband had ring sideroblastic anaemia, Christmas disease and haemochromatosis. 3 cases of ring sideroblastic anaemia were found among the 12 family members studied. Using the factor IX deficiency as a marker of the X chromosome, it appeared that autosomal transmission of the sideroblastic trait was most likely. The sideroblastic trait did not seem to be linked to HLA-A3-alloantigen. Erythrocyte morphology was normal in all non-anaemic subjects. S-ferritin was found to be increased in all 3 cases of sideroblastic anaemia as well as in 1 non-anaemic relative. Erythrocyte uroporphyrinogen-I-synthetase was elevated in 10 of the 12 family members; those with sideroblastic anaemia had the highest values indicating that uroporphyrinogen-I-synthetase is of importance in the disturbed haem-synthesis of ring sideroblastic anaemia. This interpretation is supported by the positive correlation between S-ferritin values and the uroporphyrinogen-I-synthetase activity.     

The quality and cost of medical care in Sweden

Swedish examples are used in favor of recent WHO recommendations of quality assurance. Even prior to present efforts at savings, the autopsy frequency in Swedish hospitals dropped 2% per year. Only 31% of Swedish out-patients see the same doctor on subsequent visits, and since few have a personal physician, emergency ward visits increase about 4% per year. Laboratory errors and uncertain diagnoses seem to be of the order of 20%, at least in some conditions.