Evaluation of Mannitol Salt Agar for Detection of Oxacillin Resistance in Staphylococcus aureus by Disk Diffusion and Agar Screening

Mannitol salt agar was evaluated for detection of oxacillin resistance in 136 Staphylococcus aureus isolates. All mecA-positive isolates (n = 54) were correctly categorized as oxacillin resistant by the disk diffusion test (1-μg disk; zone diameter, <16 mm); the specificity was 97.6%. Agar screening (2 μg of oxacillin per ml) revealed a sensitivity of 98.1% and a specificity of 95.1%.     

Drosophila Cyclin B3 is required for female fertility and is dispensable for mitosis like Cyclin B

Cyclin B3 has been conserved during higher eukaryote evolution as evidenced by its identification in chicken, nematodes, and insects. We demonstrate that Cyclin B3 is present in addition to Cyclins A and B in mitotically proliferating cells and not detectable in endoreduplicating tissues of Drosophila embryos. Cyclin B3 is coimmunoprecipitated with Cdk1(Cdc2) but not with Cdk2(Cdc2c). It is degraded abruptly during mitosis like Cyclins A and B. In contrast to these latter cyclins, which accumulate predominantly in the cytoplasm during interphase, Cyclin B3 is a nuclear protein. Genetic analyses indicate functional redundancies. Double and triple mutant analyses demonstrate that Cyclins A, B, and B3 cooperate to regulate mitosis, but surprisingly single mutants reveal that neither Cyclin B3 nor Cyclin B is required for mitosis. However, both are required for female fertility and Cyclin B also for male fertility.     

Glial Fibrillary Acidic Protein Expression in Pleomorphic Adenoma of Salivary Gland: An Immunoelectron Microscopic Study

Previous immunocytochemical studies of pleomorphic adenomas have demonstrated consistent labeling with glial fibrillary acidic protein (GFAP). Cross-reactivity with other intermediate filaments of similar structure and chemical composition has been suggested to account for this seemingly inappropriate pattern of immunoreactivity. To investigate further this phenomenon, we examined five pleomorphic adenomas by immunoelectron microscopy. Ultrastructural features were similar to those described by other investigators, with ductal epithelium being surrounded by myoepithelial cells and modified cells becoming detached to form the isolated stellate and spindle cells of the stroma. As part of this process, many neoplastic myoepithelial cells appeared to lose their specialized ultrastructural features, assuming a rather undifferentiated appearance. Single and double immunoelectron microscopic labeling showed vimentin filaments in all these neoplastic myoepithelial cells. In contrast, GFAP filaments were identified only in the most undifferentiated cells. Such restriction of GFAP filaments to an ultrastructurally definable subset of neoplastic cells provides strong evidence against nonspecific staining due to cross-reactivity. Given the previously described coexpression of vimentin and GFAP by neoplastic cartilage, it appears likely that this immunophenotype in neoplastic myoepithelial cells reflects early chondroid differentiation.     

The Compliance Curve for the Flow Limiting Segments of the Airway

Maximum effort flow-static recoil curves were obtained in 5 healthy subjects breathing air, He/O₂, and SF₆/O₂ mixtures. In 4 of them maximum effort flows corresponded to really maximal flows and their curves were transformed into compliance curves for the flow limiting segments of the airway and analyzed from the point of view of a previously presented lung model (Pedersen and Nielsen 1976). The results showed, that viscosity dependent pressure losses from the alveoli to the flow limiting segments were minimal for air and SF₆/O₂, but not for He/O₂. When viscosity dependent pressure losses could be neglected, then expiration of gases of different densities gave almost identical compliance curves for the flow limiting segments. This supported the applicability of the model. The calculated compliance curves for the flow limiting segments were compared with data from the literature, and the findings indicated that flow limitation during expirations with just maximal flows throughout began in the extrapulmonary airways and moved upstream during the expiration.     

Antibody response to Rocky Mountain spotted fever.

Various techniques were compared to determine the most sensitive method for detection of rocky Mountain spotted fever antibody. A radiometabolic technique for detection of Rocky Mountain spotted fever antibody is also described. In infected monkeys, the fluorescent antibody technique yielded the earliest evidence of seroconversion; with some monkeys the microagglutination procedure was equally effective. The fluorescent antibody and microagglutination measurements showed higher titers than those for complement fixation, Weil-Felix, or the radiometabolic techniques.     

Immunological reactivity of herpes simplex virus 1 and 2 polypeptides electrophoretically separated and transferred to diazobenzyloxymethyl paper.

In this paper we report that viral polypeptides from herpes simplex virus 1 (HSV-1) and 2 (HSV-2)-infected cells electrophoretically separated in sodium dodecyl sulfate-polyacrylamide-agarose gels and transferred to diazobenzyloxymethyl paper can react with rabbit hyperimmune sera, both polyvalent and prepared against specific antigens. The polyvalent hyperimmune sera against HSV-1 reacted with 17 HSV-1 polypeptide bands and 8 HSV-2 polypeptide bands. Concordantly, polyvalent sera against HSV-2 reacted with at least 16 HSV-2 polypeptide bands and 8 HSV-1 polypeptide bands. The antisera prepared against the specific antigens reacted with a smaller number of polypeptide bands. Preimmune sera and immune sera did not react with electrophoretically separated polypeptides from infected and uninfected cells, respectively. The immune localization of separated antigens test provides a powerful technique for identification of immunogenic viral polypeptides, especially those which are normally insoluble and therefore unavailable for immunological reactivity in immune precipitation tests.     

SV40-transformed cells express SV40 T antigen-related antigens on the cell surface

SV40 tumor antigen (T-Ag)-related antigens were detected serologically on the surface (surface T) of living SV40-transformed human and mouse monolayer cells by an ¹²⁵I-protein A binding assay. In immunofluorescence analysis, these cells were negative for surface T. However, on mKSA, a SV40-transformed mouse cell line grown in suspension or on SV40-transformed human and mouse monolayer cells put into suspension, surface T could be visualized by immunofluorescence microscopy. The antisera used in these experiments were raised in rabbits with purified, SDS-denatured SV40 T-Ag or came from hamsters bearing SV40 tumors. Both types of antisera had in common high titers against SV40 T-Ag (?1:1000). All these antisera were negative on normal cells or on polyoma virus-transformed cells. The specificity of both antisera for SV40 T-Ag-related binding sites on the surface of SV40-transformed cells were demonstrated by an ¹²⁵I-IgG blocking assay in which preincubation of the cells with rabbit anti-T-Ag serum inhibited the binding of hamster SV40 tumor serum to the cell surface by about 85%. These results demonstrate the expression of T-Ag-related antigens on the surface of living cells and, therefore, support the hypothesis that SV40 T-Ag-related antigens participate in the formation of the SV40-specific tumor transplantation antigen (TSTA).     

Exaggerated natriuresis in adult polycystic kidney disease

Angiotensin II (AII), aldosterone (Aldo) arginine vasopressin (AVP) in plasma, serum osmolality (Sosm), and renal sodium excretion (UNaV) were studied before and after infusion of hypertonic sodium chloride solution in 20 patients with adult polycystic kidney disease (PKD) with normal or moderately reduced creatinine clearance (Ccr) and in 10 healthy control subjects. UNaV increased after sodium loading in all, significantly more in the PKD patients. AII and Aldo were normal before sodium loading and suppressed after saline in PKD patients and controls. The increase in VNaV correlated with Aldo in patients but not in controls. AVP before loading was increased in hypertensive PKD patients with reduced Ccr, but not in normotensive patients with normal Ccr. After hypertonic saline, Sosm increased to the same degree both in PKD and control subjects, but AVP increased more in those with PKD. The exaggerated natriuresis of PKD is probably not explained by a change in the activity of the renin-angiotensin-aldosterone system. The enhanced response of AVP to osmotic stimuli in PKD may be a compensatory reaction to a reduced renal tubular effect of AVP.     

Evidence that the Cys282Tyr mutation of the HFE gene originated from a population in Southern Scandinavia and spread with the Vikings

Hereditary hemochromatosis has been recognized as a clinical disorder for more than 100 years. The common form of the disorder is caused by the Cys282Tyr mutation (C282Y) of the HFE gene. Hereditary hemochromatosis affects predominantly people of Northern European origin. The C282Y mutation probably occurred on a single chromosome carrying the ancestral hemochromatosis haplotype, which subsequently was spread by emigration and the founder effect. It has been estimated that the C282Y mutation appeared 60-70 generations ago. It was initially suggested that the ancestral C282Y mutation occurred within the Celtic group of peoples. However, we hypothesize that the distribution of the C282Y mutation in Europe is more consistent with an origin among the Germanic Iron Age population in Southern Scandinavia. From this area, the mutation could later be spread by the migratory activities of the Vikings. The aim of the present study was to evaluate the validity of these two hypotheses. Several arguments are in favor of the 'Viking hypothesis': first, the highest frequencies (5.1-9.7%) of the C282Y mutation are observed in populations in the Northern part of Europe, i.e. Denmark, Norway, Sweden, Faeroe Islands, Iceland, Eastern part of England (Danelaw) and the Dublin area, all Viking homelands and settlements. Second, the highest allele frequencies are reported among populations living along the coastlines. Third, the frequencies of the C282Y mutation decline from Northern to Southern Europe. Intermediate allele frequencies (3.1-4.8%) are seen in the populations in Central Europe, which is the original Celtic homeland. Low allele frequencies (0-3.1%) are recognized in populations in Southern Europe and the Mediterranean.