We compared the relative sensitivities of first-and-second generation branched nucleotide assays (Quantiplex HCV RNA 1.0 and 2.0, respectively, Chiron, Emeryville, Calif) for the detection of hepatitis C virus (HCV) RNA to that of a commercially available quantitative reverse transcriptase polymerase chain reaction (RT-PCR) method (Monitor, Roche Molecular Systems, Nutley, NJ) in 53 patients with chronic hepatitis C. The sensitivities of the second-generation branched DNA (bDNA) and RT-PCR assays were similar (91% and 92%, respectively), and both were significantly more sensitive (P<.001) than the first-generation method. Moreover, both assays detected HCV RNA in all 11 patients with type 2a, 2b, or 3a genoHepatitis C virus (HCV), a small single-stranded RNA virus, is the major causative agent of transfusion-associated hepatitis.1,2 The nucleotide sequence data of various HCV isolates have led to the designation of several genotypes.3-6 Genetic variants of HCV have been classified into six major genotypes, some with several subtypes, on the basis of nucleotide sequence homology and phylogenetic analysis. 7 In chronically infected individuals, HCV genotype and serum HCV RNA levels are clinically relevant because certain genotypes, such as types 2 and 3, and low level viremia are more frequently associated with a sustained response to therapy with interferon-alfa. [8][9][10][11][12] Moreover, evidence indicates that genotype lb may be associated with a more aggressive course histologically 13 Commercially available methods for quantification of HCV RNA are now available. Methods to quantitate HCV RNA are based on an adaptation of the reverse-transcriptase polymerase chain reaction (RT-PCR) or a signal amplification strategy that involves the use of enzymatically labeled branched nucleotide (bDNA).14-17 Investigators have found that quantitation with RT-PCR is not highly reproducible, because the efficiency of the reverse transcription and amplification steps may vary, and a number of falsenegative and false-positive test results may be found.14 ' 18 -19 Moreover, the efficiency of the hybridization and transcription steps could also result in nonlinearity of results when high levels of virus are present. Whereas a lack of specificity is not a problem in the bDNA assay, it does not have the inherent sensitivity of 17 An assay that reliably detects HCV RNA in serum or plasma and that is linear over a broad range of values would be useful in predicting and monitoring the response of patients during and after therapy.The first-generation bDNA assay (Quantiplex HCV RNA, 1.0, Chiron, Emeryville, Calif) has been refined with a new set of oligonucleotide probes that are based on sequence variations among different HCV isolates. This modification has been shown to enhance equal hybridization efficiencies to all known genot y p e s .

We studied the effect of maternal administration at various intervals of betamethasone, triiodothyronine (T3), or both, on fetal rat lung maturation. T(3) alone did not enhance choline incorporation to phosphatidylcholine by 20-day fetal lung expiants, or morphometric lung maturation. Betamethasone, and betamethasone plus T(3), increased both of those parameters over control and T(3) values. However, addition of T(3) offered no advantage over administration of betamethasone alone. Significant enhancement of morphometric lung maturation was already present after only 24 h of exposure to betamethasone, or to the combination of hormones. However, choline incorporation to phosphatidylcholine only increased significantly by 36 h of exposure to betamethasone with or without T(3).