A staphylococcal radioimmunoassay for detection of antibodies toMycoplasma pneumoniae

A radioimmunoassay (RIA) which depends on the property of protein A ofStaphylococcus aureus to combine with the Fc-fragment of immunoglobulins was developed.This technique was employed to measure antibodies in human and various animal sera. It could be demonstrated that the staphylococcal RIA was at least as sensitive as the previously described radioimmunoprecipitation technique in detecting antibodies toM.pneumoniae in human sera. In addition, antibodies toM.pneumoniae could be demonstrated in sera of hamsters intranasally inoculated with the organisms. Antibodies could also be demonstrated in rabbit sera after immunization withM.pneumoniae. The test proved to be considerably more sensitive than conventional tests for detection of antibodies to the organisms. The test requires only small amounts of reagents and is relatively inexpensive.The results were presented in a preliminary form at the annual meeting of the Local Branch of the American Society for Microbiology, Frankfurt, March 1976 and the 77th ordinary meeting of the Society for General Microbiology, Glasgow, September 1976     

Use of an automated multiple-locus, variable-number tandem repeat-based method for rapid and high-throughput genotyping of Staphylococcus aureus isolates

Fast and reliable genotyping methods that allow real-time epidemiological surveillance would be instrumental to monitoring of the spread of methicillin-resistant Staphylococcus aureus. We describe an automated variable-number tandem repeat-based method for the rapid genotyping of Staphylococcus aureus. Multiplex PCR amplifications with eight primer pairs that target gene regions with variable numbers of tandem repeats were resolved by microcapillary electrophoresis and automatically assessed by cluster analysis. This genotyping technique was evaluated for its discriminatory power and reproducibility with clinical isolates of various origins, including a panel of control strains previously characterized by several typing methods and collections from either long-term carriers or defined nosocomial outbreaks. All steps of this new procedure were developed to ensure a rapid turnaround time and moderate cost. The results obtained suggest that this rapid approach is a valuable tool for the genotyping of S. aureus isolates in real time.     

Amantadine therapy in renal transplant patients with hepatitis C virus infection.

BACKGROUND: To date, there is no safe and efficient treatment of hepatitis C virus (HCV) infection after renal transplantation. Recently, there were encouraging reports after using amantadine in HCV-positive immunocompetent patients. OBJECTIVES: In an open pilot study, we evaluated the efficacy and the safety of amantadine monotherapy in 8 HCV positive renal-transplant patients with chronic active hepatitis and increased alanine aminotransferase (ALT) levels. RESULTS: After 6 months of amantadine therapy (200 mg per day), there were no decrease in HCV viremia (5.87 +/- 0.37 log copies/ml at M6 versus 5.71 +/- 0.5 log copies/ml at baseline; P > 0.05). However, we found a significant decrease in ALT activity (71 +/- 17 IU/l at M6 versus 100 +/- 9 IU/l at baseline; P = 0.04), whereas the decrease in aspartate aminotransferase activity did not reach statistical significance. There were no significant changes in liver histology. The clinical and biological tolerance was very good. Finally, there were a significant decrease in cyclosporine A whole blood trough levels during therapy. CONCLUSIONS: Our study is the first one to demonstrate that amantadine monotherapy lack of efficacy in HCV renal-transplant patients. It is able to improve liver enzymes but it has no impact neither upon HCV viremia nor upon liver histology.     

Rush Hymenoptera venom immunotherapy: a safe and practical protocol for high-risk patients

BACKGROUND: Hymenoptera venom immunotherapy in allergic patients is a well-established treatment modality for the prevention of systemic anaphylactic reactions caused by insect stings. A variety of therapy regimens exists, from conventional to rush and ultrarush modalities that operate on continuous or intermittent schedules. OBJECTIVE: The aim of this study was to report the 8-year experience with our rush venom immunotherapy regimen in predominantly high-risk patients and to compare data on safety and convenience with the results of 26 studies published from 1978 to 2001. METHODS: One hundred one patients allergic to bee, yellow jacket, or hornet venom were treated with rush Hymenoptera venom immunotherapy. Diagnosis and selection of patients for venom immunotherapy were carried out according to the recommendations of the European Academy of Allergology and Clinical Immunology. We used a 4-day regimen, and the incidence and nature of systemic reactions (SRs) were documented. Fifty-two patients were treated with honeybee venom, and 49 were treated with yellow jacket venom. RESULTS: One hundred (99%) patients reached the maintenance dose. We observed 8 injection-related SRs (0.47% of all injections given) in 7 (6.9%) patients. The number of SRs was higher in patients treated with bee venom extract (12%) compared with in patients receiving yellow jacket venom extract (2%). There was no significant difference in the risk of SRs between female and male patients. The incidence of SRs was considerably lower than the average of 17.8% reported in the literature. CONCLUSION: With a rush immunotherapy regimen over a time period of 8 years in predominantly high-risk patients, the incidence of SRs was low, despite the high number of patients with bee venom allergy, who are more likely to have side effects. Epinephrine as rescue medication was never necessary, and the regimen proved to be safe and convenient for both the patients and the medical staff.     

Impact of Breast Density on Computer-Aided Detection in Full-Field Digital Mammography

The goal of this study was to evaluate the performance of a computer-aided detection (CAD) system in full-field digital mammography (Senographe 2000D, General Electric, Buc, France) in finding out carcinomas depending on the parenchymal density. A total of 226 mediolateral oblique (MLO) and 186 craniocaudal (CC) mammographic views of histologically proven cancers were retrospectively evaluated with a digital CAD system (ImageChecker V2.3 R2 Technology, Los Altos, CA, USA). Malignant tumors were detected correctly by CAD in MLO view in 84.85% in breasts with parenchymal tissue density of the American College of Radiology (ACR) type 1, in 70.33% of the ACR type 2, in 68.12% of the ACR type 3, and in 69.70% of the ACR type 4. For the CC view, similar results were found according to the ACR types. Using the chi-square and McNemar tests, there was no statistical significance. However, a trend of better detection could be seen with decreasing ACR type. In conclusion, there seems to be a tendency for breast tissue density to affect the detection rate of breast cancer when using the CAD system.     

Prevalence and characterization of a binary toxin (actin-specific ADP-ribosyltransferase) from Clostridium difficile

In addition to the two large clostridial cytotoxins (TcdA and TcdB), some strains of Clostridium difficile also produce an actin-specific ADP-ribosyltransferase, called binary toxin CDT. We used a PCR method and Southern blotting for the detection of genes encoding the enzymatic (CDTa) and binding (CDTb) components of the binary toxin in 369 strains isolated from patients with suspected C. difficile-associated diarrhea or colitis. Twenty-two strains (a prevalence of 6%) harbored both genes. When binary toxin production was assessed by Western blotting, 19 of the 22 strains reacted with antisera against the iota toxin of C. perfringens (anti-Ia and anti-Ib). Additionally, binary toxin activity, detected by the ADP-ribosyltransferase assay, was present in only 17 of the 22 strains. Subsequently, all 22 binary toxin-positive strains were tested for the production of toxins TcdA and TcdB, toxinotyped, and characterized by serogrouping, PCR ribotyping, arbitrarily primed PCR, and pulsed-field gel electrophoresis. All binary toxin-positive strains also produced TcdB and/or TcdA. However, they had significant changes in the tcdA and tcdB genes and belonged to variant toxinotypes III, IV, V, VII, IX, and XIII. We could differentiate 16 profiles by using typing methods, indicating that most of the binary toxin-positive strains were unrelated.     

Impaired responses to toll-like receptor 4 and toll-like receptor 3 ligands in human cord blood

Toll-like receptor (TLR)-4 signaling pathway plays an essential role in host defense against gram-negative bacteria while TLR-3-mediated signaling is critically involved in anti-viral immunity. To gain insight into the defects responsible for impaired Th1 responses in human newborns, we investigated the responses of human cord blood cells to lipopolysaccharide, LPS, and to polyinosinic-polycytidylic acid, Poly (I:C), ligands of TLR-4 and TLR-3, respectively. Measurement of cytokine levels revealed a profound defect in IL-12 (p70) synthesis and an increased release of IL-10 in cord blood exposed to LPS or Poly (I:C), as compared to adult blood. Moreover, Poly (I:C)-induced IFN-alpha production was found to be significantly impaired in cord blood. Phenotypic maturation of myeloid DC in response to LPS or Poly (I:C) was next compared in cord and adult blood. We observed that neonatal myeloid DC displayed decreased upregulation of CD40, CD80 whereas CD86 and HLA-DR upregulation did not differ significantly between adults and neonates. Taken together, these findings might be relevant to the increased vulnerability of human newborns to intracellular pathogens and to their inability to develop efficient Th1-type responses.     

Clinical and biological evolution of HIV-1 seroconverters in Abidjan, Côte d'Ivoire, 1997-2000

OBJECTIVE: To describe the clinical and biologic evolution of HIV-1 infection in Africa. METHODS: One hundred four HIV-1-infected individuals were identified prospectively from regular blood donors in Abidjan, C?te d'Ivoire. The date of seroconversion was estimated from results of sequential serologic tests. Biologic and clinical follow-up was performed every 6 months, starting as early as possible after seroconversion. Case management followed national guidelines. RESULTS: The median interval between estimated seroconversion and study inclusion was 9.7 months, and the median window of seroconversion was 2.8 months. At baseline, all but two patients were asymptomatic; the median CD4 + cell count was 527/mm 3 (interquartile range [IR], 395-684), and the median plasma HIV RNA level was 4.6 log 10 copies/ml (IR, 3.8-4.9). The median follow-up was 23.9 months, and 95% of the patients received primary prophylaxis with co-trimoxazole for opportunistic infections. Of the patients, 1 presented with wasting syndrome, 3 developed tuberculosis, and 17 had a Centers for Disease Control and Prevention category B-defining event. The 3-year AIDS-free and symptom-free probabilities were 96.7% (95% confidence interval [CI], 87.0-99.2] and 79.3% (95% CI, 67.5-87.2), respectively. During the first 3 years of follow-up, we observed that the median plasma viral load stabilized at >4 log 10 copies/ml and that the median CD4 + cell count declined by 20 to 25/mm 3 per year. CONCLUSION: These African seroconverters were moderately immunosuppressed. The median HIV RNA level was high and varied very little during the first 3 years, and there were few clinical events.     

Effects of interleukin 4 on CD25+CD4+ regulatory T cell function

CD25+CD4+ regulatory T cells (Tregs) contribute to the maintenance of peripheral tolerance against self and non-self. The modulatory effects of cytokines, such as interleukin 4 (IL-4) on the function of Tregs have not been explored in detail. We here report that IL-4 prevents spontaneous apoptosis and the decline of foxp3 mRNA which were found to occur during culture of isolated Tregs. Tregs exposed to IL-4 were more potent in suppressing the proliferation of na?ve CD4+ T cells and they better inhibited IFN-gamma production by CD4+ T cells as compared to Tregs cultured in medium. IL-4 also enhanced membrane IL-2Ralpha (CD25) expression on Tregs above the levels observed on freshly isolated cells. IL-4-mediated effects on Treg function persisted in Tregs from Stat6-/- mice, pointing to a Stat6-independent intracellular transduction pathway. In conclusion, our data suggest that the anti-inflammatory function of IL-4 could partly be mediated by effects on Tregs function.