Predictive value of HIV-1 replication capacity and phenotypic susceptibility scores in antiretroviral treatment-experienced patients.

OBJECTIVES: The aim of the study was to determine the prognostic value of HIV replication capacity (RC) for subsequent antiretroviral (ARV) treatment response in ARV-experienced patients. METHODS: RC and phenotypic resistance testing were performed at baseline and week 12 on plasma samples from patients randomized to undergo a 12-week ARV drug-free period (ARDFP) or initiate immediate salvage therapy (no-ARDFP group) in the Options in Management with Antiretrovirals (OPTIMA) trial. Dichotomous and incremental phenotypic susceptibility scores (dPSSs and iPSSs, respectively) were calculated. The predictive value of RC and PSS for ARV therapy response and/or ARDFP was evaluated using multivariate regression analysis and Pearson correlations. RESULTS: In 146 no-ARDFP subjects, baseline RC (50.8%) did not change at week 12 and was not correlated with CD4 cell count or viral load changes at week 12 (P=0.33 and P=0.79, respectively) or at week 24 (P=0.96 and P=0.14, respectively). dPSS predicted virological but not CD4 cell count response to ARV therapy at weeks 12, 24 and 48 (P=0.002, P<0.001 and P=0.005, respectively). RC was significantly correlated with dPSS and iPSS at baseline, but did not increase their predictive value. In the 137 ARDFP patients, RC increased significantly (from 52.4 to 85.8%), but did not predict CD4 cell count and viral load changes during ARDFP (P=0.92 and P=0.26, respectively). RC after ARDFP did not predict subsequent CD4 cell count and viral load changes 12 weeks following ARV treatment reinitiation (P=0.90 and P=0.29, respectively). CONCLUSIONS: We found no additional predictive value of replication capacity for virological or immunological responses (above what PSS provides) in patients undergoing salvage ARV treatment.

Very high quantitative tumor HER2 content and outcome in early breast cancer.

BACKGROUND: It is unknown how a very high tumor total HER2 (human epidermal growth factor receptor-2) content (H2T) influences outcome in early breast cancer treated with adjuvant trastuzumab plus chemotherapy. PATIENTS AND METHODS: H2T was measured using a novel quantitative assay (HERmark(®)) from formalin-fixed tumor tissue of 899 women who participated in the FinHer trial (ISRCTN76560285). In a chromogenic in situ hybridization (CISH) test, 197 (21.9%) patients had HER2-positive cancer and were randomly assigned to receive trastuzumab or control. RESULTS: Cancer H2T levels varied 1808-fold. High H2T levels were correlated with a positive HER2 status by CISH (P < 0.0001). A nonlinear association was present between H2T and the hazard of distant recurrence in a subpopulation treatment effect pattern plot analysis in CISH-positive disease. Patients with very high H2T (defined by ≥22-fold the median of HER2-negative cancers; 13% of CISH-positive cancers) did not benefit from adjuvant trastuzumab [hazard ratio (HR) 1.23; 95% confidence interval (CI) 0.33-4.62; P = 0.75], whereas the rest of the patients with HER2-positive disease by CISH (87%) did benefit (HR 0.52; 95% CI 0.28-1.00; P = 0.050). CONCLUSION: Patients with HER2-positive breast cancer with very high tumor HER2 content may benefit less from adjuvant trastuzumab compared with those whose cancer has more moderate HER2 content.

Identification of a subpopulation of metastatic breast cancer patients with very high HER2 expression levels and possible resistance to trastuzumab.

BACKGROUND: Patients with metastatic breast cancer (MBC) overexpressing HER2 (human epidermal growth factor receptor 2) are currently selected for treatment with trastuzumab, but not all patients respond. PATIENTS AND METHODS: Using a novel assay, HER2 protein expression (H2T) was measured in formalin-fixed, paraffin-embedded primary breast tumors from 98 women treated with trastuzumab-based therapy for MBC. Using subpopulation treatment effect pattern plots, the population was divided into H2T low (H2T < 13.8), H2T high (H2T ≥ 68.5), and H2T intermediate (13.8 ≤ H2T < 68.5) subgroups. Kaplan-Meier (KM) analyses were carried out comparing the groups for time to progression (TTP) and overall survival (OS). Cox multivariate analyses were carried out to identify correlates of clinical outcome. Bootstrapping analyses were carried out to test the robustness of the results. RESULTS: TTP improved with increasing H2T until, at the highest levels of H2T, an abrupt decrease in the TTP was observed. KM analyses demonstrated that patients with H2T low tumors [median TTP 4.2 months, hazard ratio (HR) = 3.7, P < 0.0001] or H2T high tumors (median TTP 4.6 months, HR = 2.7, P = 0.008) had significantly shorter TTP than patients whose tumors were H2T intermediate (median TTP 12 months). OS analyses yielded similar results. CONCLUSIONS: MBC patients with very high levels of H2T may represent a subgroup with de novo resistance to trastuzumab. These results are preliminary and require confirmation in larger controlled clinical cohorts.

Antiviral activity and cross-resistance profile of P-1946, a novel human immunodeficiency virus type 1 protease inhibitor.

The HIV protease inhibitor P-1946 is a member of a novel family of l-Lysine derivatives. The compound is a specific HIV-1 protease inhibitor that has potent and selective in vitro antiviral activity (EC50 152 nM) against a range of isolates resistant to commercially available protease inhibitors. The presence of at least four primary and four secondary drug resistance mutations is required to achieve greater than four-fold resistance to P-1946. P-1946's favorable resistance profile makes it a good lead for the development of new agents active against existing PI-resistant virus in treatment-experienced patient.

Advances in quantitative PCR technology: 5' nuclease assays.

The development of 5' nuclease assays represents a significant advance in nucleic acid quantitation. This approach utilizes the 5'-3' exonuclease activity of Thermus aquaticus (Taq) polymerase to cleave a dual-labelled probe annealed to a target sequence during amplification. The release of a fluorogenic tag from the 5' end of the probe is proportional to the target sequence concentration (copy number), and can be measured either at endpoint (post-amplification), or in real time', where the increase in emission intensity is followed on a per-cycle basis.

Sequencing of protease inhibitor therapy: insights from an analysis of HIV phenotypic resistance in patients failing protease inhibitors.

OBJECTIVE: To characterize the pattern of HIV-1 susceptibility to protease inhibitors in patients failing an initial protease inhibitor-containing regimen. DESIGN: A cross-sectional analysis of antiretroviral susceptibility. SETTING: HIV clinics in six metropolitan areas. PATIENTS: Eighty-eight HIV-infected adults with HIV RNA > 400 copies/ml after > or = 6 months of antiretroviral therapy, including the use of one protease inhibitor for > or = 3 months. MEASUREMENTS: The frequency and magnitude of decreased susceptibility, measured with a phenotypic assay using recombinant constructs, to five protease inhibitors. Decreased susceptibility was defined as > 2.5-fold increase in the 50% inhibitory concentration (IC50) compared with drug sensitive control virus. RESULTS: At study entry, patients were being treated with nelfinavir (63%), indinavir (25%), or another protease inhibitor (11%). HIV isolates from these patients were susceptible (fold change < 2.5) to all five protease inhibitors in 18% of patients and to none in 8%. Isolates from patients receiving nelfinavir were less likely to have reduced susceptibility to other protease inhibitors than isolates from patients treated with indinavir (P < 0.001) or one of the other three agents (P < 0.001), even after adjustment for the duration of prior protease inhibitor use. Reduced susceptibility to saquinavir and amprenavir was observed significantly less frequently than for the other protease inhibitors. CONCLUSION: The frequency of protease inhibitor cross-resistance and the magnitude of changes in susceptibility varied according to the initial protease inhibitor used in the failing treatment regimen. Significantly less protease inhibitor cross-resistance was demonstrated for isolates from patients failing a nelfinavir-containing regimen compared with those from patients receiving other protease inhibitors.

Management of local residual primary lesion of nasopharyngeal carcinoma: II. Results of prospective randomized trial on booster dose.

Although the question of booster dose for residual primary lesion arises in only 5% of nasopharyngeal carcinoma patients receiving radiotherapy, it poses a difficult problem for clinicians and should be followed. Hence, to test the validity of booster dose for residual primary lesion of nasopharyngeal carcinoma, a prospective randomized trial has been designed and carried out since January 1980. All patients who had a residual lesion in the nasopharynx at 70 Gy were biopsied. Those pathologically positive for cancer were randomized into two groups: (a) positive radiation group (PRG): patients were given further irradiation to a total dose of 90 Gy by the cone-down and assault technique, and (b) positive observation group (POG): patients were given no more irradiation but were followed periodically together with those who were pathology negative (NOG). A total of 78 patients were entered. The validity of booster dose was shown by the 5-year survival rates of the PRG, POG and NOG groups: 75% (3/4), 33% (1/3), and 58% (14/24), respectively. The total local recurrence rates of these groups were 6% (1/16), 36% (5/14), and 4% (2/48), respectively. The authors believe that booster dose for pathology positive residual lesion in the nasopharynx is necessary. The four factors leading to the development of a local recurrence are: (a) residual primary lesion proved positive by pathology but left unboosted, (b) well differentiated squamous cell carcinoma in the original primary lesion, (c) mild radio-response in the cancer parenchyma, and (d) mild radio-response in the interstitial tissue.

Reduced mortality in murine cytomegalovirus infected mice following prophylactic murine interferon-gamma treatment.

Efficacy of recombinant DNA-derived murine IFN-gamma was investigated in a murine model of cytomegalovirus infection. Treatment of 3-week-old Swiss Webster mice with murine IFN-gamma prior to infection with murine cytomegalovirus (MCMV) significantly reduced mortality due to MCMV infection. Efficacy was dose-dependent and was observed using either intraperitoneal or intramuscular injection as the route of administration. Two doses, one at 24 h and one at 4 h prior to MCMV infection, were required for optimum efficacy, and doses administered after MCMV infection had no apparent effect. Reduced infectious MCMV titers were observed in critical organs of IFN-gamma treated mice and histopathologic lesions induced by MCMV infection were in general less severe and resolved sooner than lesions in untreated mice. Results in this murine model of cytomegalovirus infection suggest that IFN-gamma treatment may be useful as prophylactic therapy for human cytomegalovirus infections when a high probability of exposure to the virus exists and consequences of infection may be severe.

Effects of tumor necrosis factor-alpha treatment on mortality in murine cytomegalovirus-infected mice.

The effects of treatment with recombinant DNA-derived Tumor Necrosis Factor-alpha (TNF-alpha) in a murine model of cytomegalovirus infection were investigated. Treatment of 3-week-old Swiss Webster mice with murine TNF-alpha prior to infection with murine cytomegalovirus (MCMV) had no demonstrable effect on mortality. However, if mice were treated prior to infection with a combination of murine IFN-gamma and murine TNF-alpha, the dose of IFN-gamma required to achieve significant reduction in mortality was reduced by a factor > 10. In contrast to the beneficial effects of prophylactic TNF-alpha treatment in combination with IFN-gamma, TNF-alpha treatment of mice after MCMV infection resulted in increased mortality. The increased mortality occurred when nonlethal doses of TNF-alpha were used and required virus replication. The effects of TNF-alpha treatment on mortality in MCMV-infected mice were not predicted from cell culture experiments which evaluated the effects of TNF-alpha treatment on MCMV replication in primary mouse embryo fibroblasts.

Quantitative competitive reverse transcription-PCR as a method to evaluate retrovirus removal during chromatography procedures.

Chinese hamster ovary cells used for pharmaceutical protein production express non-infectious retrovirus-like particles. To assure the safety of pharmaceutical proteins, validation of the ability of manufacturing process to clear retrovirus-like particles is required for product registration. Xenotropic murine leukemia virus (X-MuLV) is often used as a model virus for validation studies. Some chromatography procedures used for pharmaceutical protein purification utilize low pH (< pH 4.0) elution buffers which readily inactivate X-MuLV. Therefore, cell-based infectivity assays are unable to evaluate the physical removal of X-MuLV by these chromatography procedures. To distinguish viral inactivation by low pH treatment from viral removal by chromatography, a quantitative competitive reverse transcription PCR method capable of quantifying both infectious and non-infectious X-MuLV has been developed. This method quantifies X-MuLV particles in chromatography pools by quantifying the X-MuLV particle RNA (pRNA). The difference between the amount of X-MuLV pRNA in the load pool and the product-containing elution pool represents the extent of X-MuLV removal. This method is an extremely powerful complement to cell based-infectivity assays as it allows physical removal of X-MuLV by chromatography and filtration procedures to be distinguished from X-MuLV inactivation when buffers with the ability to inactivate retrovirus are used.

Randomised comparison of the Classic Laryngeal Mask Airway with the Cobra Perilaryngeal Airway during anaesthesia in spontaneously breathing adult patients.

We tested the hypothesis that the Cobra Perilaryngeal Airway (PLA) with its high volume low-pressure cuff would provide superior airway leakage pressure compared with the Classic Laryngeal Mask Airway (LMA) in spontaneously breathing adult patients. Ninety consecutive adult patients were randomly allocated to receive one of these two supralaryngeal devices. The airway leakage pressure was higher for the PLA compared with the LMA (22 +/- 9 cmH2O vs. 18 +/- 6 cmH2O; P < 0.05). The mean airway device intracuff pressure was lower for the PLA compared to the LMA (36.1 +/- 15.2 mmHg vs. 86.3 +/- 25.3 mmHg P < 0.0001). The time required to achieve successful insertion was greater for the PLA compared with the LMA (39 +/- 21 seconds vs. 27 +/- 10 seconds; P < 0.005). The number of attempts required to achieve successful insertion and the incidence of postoperative complications were similar in both groups. The findings suggest that the PLA provides a superior airway seal at a lower intracuff pressure compared to the LMA. However the time for successful insertion may be increased.

In vitro translation extracts prepared from Drosophila ovaries and embryos.

Translational regulation has emerged as an important feature of animal development, especially in the embryo prior to the onset of zygotic transcription. Specialized forms of control regulate the translation of individual mRNAs, and the factors involved in these mRNA-specific events are expected to be found in only a subset of all tissues. Consequently, homologous in vitro translation systems, prepared from tissues in which important regulatory events occur, are likely to be required to pursue biochemical studies of the underlying mechanisms. Here we describe the characterization of extracts prepared from Drosophila ovaries and embryos that support translation of exogenous reporter mRNAs in vitro. These in vitro systems should prove to be useful in dissecting mechanisms of the numerous translational control events shown to occur during the early stages of Drosophila development.

Apontic binds the translational repressor Bruno and is implicated in regulation of oskar mRNA translation.

The product of the oskar gene directs posterior patterning in the Drosophila oocyte, where it must be deployed specifically at the posterior pole. Proper expression relies on the coordinated localization and translational control of the oskar mRNA. Translational repression prior to localization of the transcript is mediated, in part, by the Bruno protein, which binds to discrete sites in the 3' untranslated region of the oskar mRNA. To begin to understand how Bruno acts in translational repression, we performed a yeast two-hybrid screen to identify Bruno-interacting proteins. One interactor, described here, is the product of the apontic gene. Coimmunoprecipitation experiments lend biochemical support to the idea that Bruno and Apontic proteins physically interact in Drosophila. Genetic experiments using mutants defective in apontic and bruno reveal a functional interaction between these genes. Given this interaction, Apontic is likely to act together with Bruno in translational repression of oskar mRNA. Interestingly, Apontic, like Bruno, is an RNA-binding protein and specifically binds certain regions of the oskar mRNA 3' untranslated region.

Translational regulation of oskar mRNA occurs independent of the cap and poly(A) tail in Drosophila ovarian extracts.

Translational regulation plays a prominent role in Drosophila body patterning. Progress in elucidating the underlying mechanisms has been limited by the lack of a homologous in vitro system that supports regulation. Here we show that extracts prepared from Drosophila tissues are competent for translation. Ovarian extracts, but not embryonic extracts, support the Bruno response element- and Bruno-dependent repression of oskar mRNA translation, which acts in vivo to prevent protein synthesis from transcripts not localized to the posterior pole of the oocyte. Consistent with suggestive evidence from in vivo experiments, regulation in vitro does not involve changes in poly(A) tail length. Moreover, inhibition studies strongly suggest that repression does not interfere with the process of 5' cap recognition. Translational regulation mediated through the Bruno response elements is thus likely to occur via a novel mechanism.

Endogenous origin of defective retroviruslike particles from a recombinant Chinese hamster ovary cell line.

The presence of budding C-type and intracytoplasmic A-type particles in Chinese hamster ovary (CHO) cells is well documented. However, extensive screening has failed to detect any evidence of infectivity. Continuous-flow ultracentrifugation has been used to concentrate extracellular particles from culture fluid of a recombinant CHO cell subclone for molecular characterization. Particles exhibiting reverse transcriptase activity and associated with mammalian C-type retrovirus structural proteins banded in sucrose gradients at a density characteristic of retroviruses. Examination of gradient-purified particles by electron microscopy revealed morphology and size similar to other retroviruses. Double-gradient-purified particles contained RNA which hybridized to probes for murine leukemia virus, and endogenous Chinese hamster intracisternal A-particle elements. DNA sequence analysis of a cDNA clone isolated from purified particles revealed multiple interruptions of the endonuclease reading frame, providing one possible explanation for the noninfectious nature of the observed particles. Sequences present as RNA in purified particles were also present as conserved, repetitive, provirus sequences in genomic DNA of all CHO cell lines examined and in Chinese hamster liver DNA. The observed particles are therefore likely to be the products of endogenous retroviruslike elements present in the germline of Chinese hamsters.