Is intrapartum fever associated with ST-waveform changes of the fetal electrocardiogram? A retrospective cohort study

Please cite this paper as: Becker J, van Rijswijk J, Versteijnen B, Evers A, van den Akker E, van Beek E, Bolte A, Rijnders R, Mol B, Moons K, Porath M, Drogtrop A, Schuitemaker N, Willekes C, Westerhuis M, Visser G, Kwee A. Is intrapartum fever associated with ST-waveform changes of the fetal electrocardiogram? A retrospective cohort study. BJOG 2012;119:1410-1416. Objective To investigate the association between maternal intrapartum fever and ST-waveform changes of the fetal electrocardiogram. Design Retrospective cohort study. Setting Three academic and six non-academic teaching hospitals in the Netherlands. Population Labouring women with a high-risk singleton pregnancy in cephalic position beyond 36?weeks of gestation. Methods We studied 142 women with fever (≥38.0°C) during labour and 141 women with normal temperature who had been included in two previous studies. In both groups, we counted the number and type of ST-events and classified them as significant (intervention needed) or not significant, based on STAN(?) clinical guidelines. Main outcome measures Number and type of ST-events. Results Both univariable and multivariable regression analysis showed no association between the presence of maternal intrapartum fever and the number or type of ST-events. Conclusions Maternal intrapartum fever is not associated with ST-segment changes of the fetal electrocardiogram. Interpretation of ST-changes in labouring women with fever should therefore not differ from other situations.     

In vitro replication capacity of HIV-2 variants from long-term aviremic individuals

To establish whether efficient suppression of virus replication in HIV-2-infected individuals is associated with low replicative capacity of HIV-2, replication kinetics of HIV-2 variants from long-term aviremic individuals was analyzed and compared with that of the relatively slow-replicating HIV-1 variants from asymptomatics and long-term nonprogressors (AS/LTNP). On average, HIV-2 from aviremic individuals had lower replication rates than HIV-1 variants from AS/LTNP in cells of 8 donors (0.45 log10 [range 0.14-0.77] vs. 0.58 log10 [range 0.32-0.99] pg RT/ml/day, P = 0.036). The relatively low replication rate of HIV-2 compared to HIV-1 variants was not related to different sensitivities to inhibition by CD8+ T cells or different degrees of infectivity. HIV-2 replication rates increased with progressive infection and with switch from CCR5 to CXCR4 usage. The relatively low replicative capacity of HIV-2 variants from aviremic individuals likely contributes to the low viral load and benign course of infection in these individuals.     

Comparison of Human Immunodeficiency Virus Type 1 Tropism Profiles in Clinical Samples by the Trofile and MT-2 Assays

The recent availability of CCR5 antagonists as anti-human immunodeficiency virus (anti-HIV) therapeutics has highlighted the need to accurately identify CXCR4-using variants in patient samples when use of this new drug class is considered. The Trofile assay (Monogram Biosciences) has become the method that is the most widely used to define tropism in the clinic prior to the use of a CCR5 antagonist. By comparison, the MT-2 assay has been used since early in the HIV epidemic to define tropism in clinical specimens. Given that there are few data from direct comparisons of these two assays, we evaluated the performance of the plasma-based Trofile assay and the peripheral blood mononuclear cell (PBMC)-based MT-2 assay for the detection of CXCR4 use in defining the tropism of HIV isolates derived from clinical samples. The various samples used for this comparison were derived from participants of the Amsterdam Cohort Studies on HIV infection and AIDS who underwent consecutive MT-2 assay testing of their PBMCs at approximately 3-month intervals. This unique sample set was specifically selected because consecutive MT-2 assays had demonstrated a shift from negative to positive in PBMCs, reflecting the first emergence of CXCR4-using virus in PBMCs above the level of detection of the assay in these individuals. Trofile testing was performed with clonal HIV type 1 (HIV-1) variants (n = 21), MT-2 cell culture-derived cells (n = 20) and supernatants (n = 42), and plasma samples (n = 76). Among the clonal HIV-1 variants and MT-2 cell culture-derived samples, the results of the Trofile and MT-2 assays demonstrated a high degree of concordance (95% to 98%). Among consecutive plasma samples, detection of CXCR4-using virus was at or before the time of first detection by the MT-2 assay in 5/10 patients by the original Trofile assay and in 9/10 patients by the enhanced-sensitivity Trofile assay. Differences in the time to the first detection of CXCR4 use between the MT-2 assay (PBMCs) and the original Trofile assay (plasma) were greatly reduced by the enhanced-sensitivity Trofile assay, suggesting that sensitivity for the detection of minor CXCR4-using variants may be a more important determinant of discordant findings than compartmentalization. The similarities in performance of the enhanced-sensitivity Trofile and MT-2 assays suggest that either may be an appropriate methodology to define tropism in patient specimens.The outcome of exposure to human immunodeficiency virus type 1 (HIV-1) varies greatly between individuals. One of the factors determining this variability in outcome is the cellular tropism or viral phenotype (7, 23), as the pathogenesis of HIV-1 is critically influenced by the cell types that the virus is capable of infecting. HIV-1 requires two cellular receptors for entry: CD4 and one of a family of chemokine receptors (coreceptor). In vivo, the major coreceptors used by HIV-1 are CCR5 (1, 13, 14) and CXCR4 (15). Individual viruses are classified on the basis of their ability to use CCR5 (R5 variants) or CXCR4 (X4 variants), or both (R5X4 or dual variants) (2). Viral populations demonstrating the use of both receptors are designated dual/mixed (D/M), as they may contain any mixture of these three types (43). Before the identification of HIV coreceptors, viruses were classified on the basis of their ability to infect T-cell lines and/or macrophages and/or on the basis of their ability to induce syncytia (multinucleated giant cells) in MT-2 cells (16, 36) which do not express CCR5 (11). Thus, viruses that do not infect MT-2 cells are non-syncytium inducing and R5, while viruses that do infect MT-2 cells are syncytium inducing and either X4 or R5X4 (4). Determinants that govern coreceptor use have been mapped to the envelope gene, especially to the variable regions, and in particular the third variable (V3) region, the V3 loop (12, 17).Of note, the ability to induce syncytia in MT-2 cells reflects the viral coreceptor use and not necessarily the enhanced cytopathogenicity of X4 virus per se, as R5 virus can at least be equally cytopathogenic to its target cells (18, 26, 33). The differential pathogenicity of R5 and X4 viruses in vivo mainly lies in the coreceptor expression patterns of the host cells. CXCR4 is expressed on many more CD4⁺ cells in the body (including hematopoietic progenitor cells, thymocytes, naïve T cells, and monocytes) than CCR5, which is mostly found on memory T cells and macrophages (3, 6). Thus, CXCR4 use potentially allows the virus access to a large and critical pool of target cells affecting T-cell ontogeny, a fact that may be relevant to the accelerated CD4⁺ T-cell decline associated with the emergence of CXCR4-using virus (5). Therefore, detection of the emergence of CXCR4-using virus has potential value for predicting pathogenesis, monitoring disease progression, and making treatment decisions. Moreover, the detection of CXCR4-using variants is required for the optimal use of the recently available CCR5 antagonists as HIV therapeutics, as the activity of CCR5 antagonists in patients is attenuated in the presence of CXCR4-using HIV (27).Traditionally, the MT-2 assay has served as a tool for the determination of tropism on the basis of the expression of CXCR4 (and not CCR5) on the cell surface. There are a wealth of data correlating the detection of CXCR4-using virus by the MT-2 assay and accelerated disease progression in treatment-naïve individuals (7, 8, 23, 29, 32). Two widely used versions of the MT-2 assay exist: one in which the patient''s cells are directly cocultured with the MT-2 cells (25) and another in which virus stocks are first generated from the patient''s cells by coculture with seronegative phytohemagglutinin-stimulated peripheral blood mononuclear cells (PBMCs) (22). The latter approach may limit the sensitivity of the assay, as MT-2 cells are more sensitive to infection by CXCR4-using virus than PBMCs. Moreover, PBMC passaging of patient samples prior to MT-2 inoculation has the potential to alter the relative proportions of viral subpopulations present in the original sample (42). Although the MT-2 assay is not technically challenging, the need for viable patient cells (either fresh or cryopreserved) and biosafety level 3 laboratories has limited its widespread implementation.By comparison, the Trofile assay (Monogram Biosciences) was utilized in the MOTIVATE trials, which led to the approval of maraviroc, the first in the class of CCR5 antagonists (19). This assay, specifically adapted for high-throughput testing of patient samples, is available in 35 countries; and with more than 54,000 samples tested to date, the assay is the only clinically validated test available for the screening of patients considering CCR5 antagonist therapy (9, 19, 21, 28, 30, 44). The Trofile assay evaluates the coreceptor use of recombinant luciferase-reporter viruses pseudotyped with a population (or clones) of patient-derived HIV envelopes in a single-cycle infection assay. The original version of the assay was validated to detect low-level X4 or R5 variants with 100% sensitivity when those variants comprised 10% of a mixed HIV envelope population and with 85% sensitivity when those variants comprised 5% of a population (43). Clinical trial data indicated that an improved sensitivity for the detection of low-level CXCR4-using variants might improve the selection of patients for CCR5 antagonist therapy (19, 20). Therefore, an enhanced version of the Trofile assay with an approximately 30-fold increased sensitivity for the detection of low-level X4 variants was developed and validated to detect low-level X4 variants with 100% sensitivity when the variants comprised as little as 0.3% of a mixed envelope population (31). Retrospective analyses of two studies evaluating CCR5 antagonist activity among individuals with R5 tropism defined by the original Trofile assay demonstrated improved outcomes among those with R5 tropism defined by the enhanced-sensitivity Trofile assay (34, 35). The assay with enhanced sensitivity replaced the original Trofile assay in the clinic in June 2008.In this study we explored the performance of the Trofile assay for the detection of HIV-1 tropism profiles in clinical specimens derived from individuals in whom consecutive MT-2 assays at 3-month intervals had detected the emergence of CXCR4-using virus in PBMCs for the first time. The samples tested were plasma, clonal HIV-1 variants, and cells and cell-free supernatants derived from MT-2 cell cultures. Testing of clonal HIV-1 variants and samples derived from MT-2 cell cultures allowed a comparison of the tropism characterization of homogeneous viral populations. Testing of consecutive patient samples allowed interrogation of the performance of both the MT-2 assay (with PBMCs) and the Trofile assay (with plasma) near the limits of detection for CXCR4-using variants.     

Complex-type N-glycan recognition by potent broadly neutralizing HIV antibodies

Broadly neutralizing HIV antibodies (bNAbs) can recognize carbohydrate-dependent epitopes on gp120. In contrast to previously characterized glycan-dependent bNAbs that recognize high-mannose N-glycans, PGT121 binds complex-type N-glycans in glycan microarrays. We isolated the B-cell clone encoding PGT121, which segregates into PGT121-like and 10-1074–like groups distinguished by sequence, binding affinity, carbohydrate recognition, and neutralizing activity. Group 10-1074 exhibits remarkable potency and breadth but no detectable binding to protein-free glycans. Crystal structures of unliganded PGT121, 10-1074, and their likely germ-line precursor reveal that differential carbohydrate recognition maps to a cleft between complementarity determining region (CDR)H2 and CDRH3. This cleft was occupied by a complex-type N-glycan in a “liganded” PGT121 structure. Swapping glycan contact residues between PGT121 and 10-1074 confirmed their importance for neutralization. Although PGT121 binds complex-type N-glycans, PGT121 recognized high-mannose-only HIV envelopes in isolation and on virions. As HIV envelopes exhibit varying proportions of high-mannose- and complex-type N-glycans, these results suggest promiscuous carbohydrate interactions, an advantageous adaptation ensuring neutralization of all viruses within a given strain.Antibodies are essential for the success of most vaccines (1), and antibodies against HIV appear to be the only correlate of protection in the recent RV144 anti-HIV vaccine trial (2). Some HIV-1–infected patients develop broadly neutralizing serologic activity against the gp160 viral spike 2–4 y after infection (3–10), but these antibodies do not generally protect infected humans because autologous viruses escape through mutation (11–13). Nevertheless, broadly neutralizing activity puts selective pressure on the virus (13) and passive transfer of broadly neutralizing antibodies (bNAbs) to macaques protects against simian/human immunodeficiency virus (SHIV) infection (14–24). It has therefore been proposed that vaccines that elicit such antibodies may be protective against HIV infection in humans (10, 25–28).The development of single-cell antibody cloning techniques revealed that bNAbs target several different epitopes on the HIV-1 gp160 spike (29–35). The most potent HIV-1 bNAbs recognize the CD4 binding site (CD4bs) (31, 34, 36) and carbohydrate-dependent epitopes associated with the variable loops (32, 33, 37, 38), including the V1/V2 (antibodies PG9/PG16) (33) and V3 loops (PGTs) (32). Less is known about carbohydrate-dependent epitopes because the antibodies studied to date are either unique examples or members of small clonal families.To better understand the neutralizing antibody response to HIV-1 and the epitope targeted by PGT antibodies, we isolated members of a large clonal family dominating the gp160-specific IgG memory response from the clade A-infected patient who produced PGT121. We report that PGT121 antibodies segregate into two groups, a PGT121-like and a 10-1074–like group, according to sequence, binding affinity, neutralizing activity, and recognition of carbohydrates and the V3 loop. The 10-1074 antibody and related family members exhibit unusual potent neutralization, including broad reactivity against newly transmitted viruses. Unlike previously characterized carbohydrate-dependent bNAbs, PGT121 binds to complex-type, rather than high-mannose, N-glycans in glycan microarray experiments. Crystal structures of PGT121 and 10-1074 compared with structures of their germ-line precursor and a structure of PGT121 bound to a complex-type N-glycan rationalize their distinct properties.     

Clothing and bedding and its relevance to sudden infant death syndrome: Further results from the New Zealand Cot Death Study

As part of a large nationwide case-control study covering a region with 78% of all births in New Zealand during 1987–90, the clothing and bedding of infants dying of sudden infant death syndrome (SIDS) and that of an appropriate control group were recorded. Cases consisted of 81% (n= 393) of all cases of SIDS in the study area and 88.4% (n= 1592) of 1800 control infants randomly selected from the hospital births and who completed a home interview. Use of a wool ‘waterproof’ underblanket was associated with a significantly reduced risk of SIDS (adjusted OR 0.44; 95% CI: 0.26-0.73) while sheepskin use was not. Firm tucking was identified as contributing to a reduced risk of SIDS even after adjusting for potentially confounding variables (adjusted OR 0.63, 95% CI: 0.46–0.86). Sixty case infants (15.6% of cases) were found dead with the head covered but there were no equivalent data for controls. Having been found previously completely covered by bedding was equally common in cases and controls (28.8% cases and 30.6% of control infants). Other differences of bedding and clothing between cases and controls were small; mattress characteristics were not studied. The exact methods in which babies are cared for are important and this study suggests that infants are at lower risk of SIDS when firmly tucked in and when sleeping on a ‘waterproof wool underblanket.     

Macrophage-tropic variants initiate human immunodeficiency virus type 1 infection after sexual, parenteral, and vertical transmission.

Macrophage-tropic, non-syncytium-inducing, HIV-1 variants predominate in the asymptomatic phase of infection and may be responsible for establishing infection in an individual exposed to the mixture of HIV-1 variants. Here, genotypical and phenotypical characteristics of virus populations, present in sexual, parenteral, or vertical donor-recipient pairs, were studied. Sequence analysis of the V3 domain confirmed the presence of a homogeneous virus population in recently infected individuals. Biological HIV-1 clones were further characterized for syncytium inducing capacity on the MT2 cell line and for macrophage tropism as defined by the appearance of proviral DNA upon inoculation of monocyte-derived macrophages. Both sexual and parenteral transmission cases revealed a selective outgrowth in the recipient of the most macrophage-tropic variant(s) present in the donor. In three out of five vertical transmission cases, more than one highly macrophage-tropic virus variant was present in the child shortly after birth, suggestive of transmission of multiple variants. In three primary infection cases, homogeneous virus populations of macrophage-tropic, non-syncytium-inducing variants were present prior to seroconversion, thus excluding humoral immunity as the selective pressure in favour of macrophage-tropic variants. These observations may have important implications for vaccine development.     

Vital exhaustion as a risk indicator for first stroke

Fatigue is a common condition after stroke. An unresolved question is whether the fatigue is a consequence of the stroke or is one of the precursors. The authors' objective was to investigate whether vital exhaustion is a precursor of first stroke while controlling for other cardiovascular risk factors. The design was a prospective cohort study. Vital exhaustion was diagnosed with the Maastricht Interview Vital Exhaustion scale. The authors controlled for age, gender, diabetes mellitus, systolic and diastolic blood pressure, total cholesterol, body mass index, and smoking habits as possible confounders. Data were analyzed with Cox regression analysis. The subjects were adults ages 41-66 in an average Dutch village population. Outcome measures included first stroke. Vital exhaustion increased the risk of stroke by 13% per vital exhaustion point on the Maastricht Interview Vital Exhaustion scale. This value remained statistically significant after control for other risk factors. Total cholesterol, diastolic blood pressure, systolic blood pressure, diabetes mellitus, and smoking also increased the risk of stroke significantly. A state of exhaustion is one of the risk indicators for stroke. This means that the fatigue so often seen after stroke was already experienced by many patients before the occurrence of the stroke.