RESUMO
With the availability of anticytomegalovirus (CMV) therapeutic agents, rapid detection of CMV is important in the care and management of the immunosuppressed patient. The PrimeCapture CMV DNA Detection Plate System (PC-PCR) was evaluated for the detection of CMV in blood and cerebrospinal fluid (CSF). The resolution of discordant results was performed by consensus testing utilizing a combination of conventional cell culture (TC-CPE), the CMV-antigenemia (CMV-Ag) assay, one or more in-house CMV nested PCR assays, and/or patient evaluation and follow-up. Of 51 blood specimens from 34 patients, 23 (45%) were identified as true positives. PC-PCR was significantly more sensitive than the CMV-Ag assay, TC-CPE, or a combination of both tests. The sensitivities, specificities, positive predictive values (PPV), and negative predictive values (NPV) for PC-PCR, the CMV-Ag assay, TC-CPE, and a combination of CMV-Ag and TC-CPE were 78, 75, 72, 81%; 46, 100, 100, 70%; 39, 100, 100, 67%; and 58, 100, 100, 73%, respectively. CMV was not detected or isolated in CSF, resulting in a combined PC-PCR sensitivity, specificity, PPV, and NPV of 77, 90, 68, and 93%, respectively. Among those laboratorians considering the incorporation of molecular CMV diagnostics into their clinical microbiology or virology laboratories, the CMV PC-PCR offers a relatively simple-to-perform and sensitive assay system.
Assuntos
Infecções por Citomegalovirus/virologia , Citomegalovirus/isolamento & purificação , DNA Viral/análise , Reação em Cadeia da Polimerase/métodos , Citomegalovirus/genética , DNA Viral/genética , Humanos , Sensibilidade e EspecificidadeRESUMO
Bovine casein submicelles and reformed micelles, produced by addition of Ca2+, were examined by Fourier transform infrared spectroscopy at 15 and 37 degrees C in aqueous salt solutions of K+ and Na+. Previous measurements of caseins, made in D2O and in the solid form, can now be made in a more realistic environment of H2O. When analyzed in detail, data obtained by Fourier transform infrared spectroscopy have the potential to show subtle changes in secondary structural elements that are associated with changes in protein environment. Electrostatic binding of Ca2+ to casein resulted in a redistribution of the components of the infrared spectra. Addition of Ca2+ in salt solutions of K+ and Na+ led to apparent decreases in large loop or helical structures at 37 degrees C with concomitant increases in the percentage of structures having greater bond energy, such as turns and extended helical structures. At 15 degrees C, Na+ and K+ have differential effects on the Ca(2+)-casein complexes. All of these observations are in accordance with the important role of serine phosphate side chains as sites for Ca2+ binding in caseins and the swelling of the casein structure upon incorporation into reformed micelles at 37 degrees C. This new open, hydrated structure is buttressed by a change in backbone as evidenced by a shift in absorbance to higher wave numbers (greater bond energies) as colloidal micelles are reformed.
