Sizing and mending of appendicular muscle mass for hydration during the 12-lead electrocardiogram: True incidence of sarcopenia in heart failure

BACKGROUND

Our aim was to develop and evaluate a method for the measurement of muscle mass during the 12-channel electrocardiogram (ECG), to determine the incidence of sarcopenia in patients with overhydration and to correct it for congestion.

METHODS

A 12-channel ECG that simultaneously provided multifrequency segmental impedance data was used to measure total body water (TBW), extracellular water (ECW), ECW/TBW ratio and appendicular muscle mass (AppMM), validated by whole-body dual-energy X-ray absorptiometry. The mean ECW/TBW ratio was 0.24 ± 0.018 (SD) and 0.25 ± 0.016 for young (age range 20-25 years) healthy males (n = 77) and females (n = 88), respectively. The deviation of the ECW/TBW ratio from this mean was used to correct AppMM for excess ECW ('dry AppMM') in 869 healthy controls and in 765 patients with chronic heart failure (CHF) New York Heart Association classes II-IV. The association of AppMM and dry AppMM with grip strength was also examined in 443 controls and patients.

RESULTS

With increasing N-terminal pro-brain natriuretic peptide (NT-proBNP), a continuous decline of AppMM indices is observed, which is more pronounced for dry AppMM indices (for males with NT-proBNP < 125 pg/mL: AppMM index mean = 8.4 ± 1.05, AppMM index dry mean = 8.0 ± 1.46 [n = 201, P < 0.001]; for females with NT-proBNP < 150 pg/mL: AppMM index mean = 6.4 ± 1.0, AppMM index dry mean = 5.8 ± 1.18 [n = 198, P < 0.001]; for males with NT-proBNP > 1000 pg/mL: AppMM index mean = 7.6 ± 0.98, AppMM index dry mean = 6.2 ± 1.11 [n = 137, P < 0.001]; and for females with NT-proBNP > 1000 pg/mL: AppMM index mean = 5.9 ± 0.96, AppMM index dry mean = 4.8 ± 0.94 [n = 109, P < 0.001]). The correlation between AppMM and upper-body AppMM and grip strength (r-value) increased from 0.79 to 0.83 (P < 0.001) and from 0.80 to 0.84 (P < 0.001), respectively, after correction (n = 443). The decline of AppMM with age after correction for ECW is much steeper than appreciated, especially in males: In patients with CHF and sarcopenia, the incidence of sarcopenia may be up to 30% higher after correction for ECW excess according to the European (62% vs. 57%, for males, and 43% vs. 31%, for females) and Foundation for the National Institutes of Health (FNIH) (56% vs. 46%, for males, and 54% vs. 38%, for females) consensus guidelines.

CONCLUSIONS

The incidence of sarcopenia in CHF as defined by the European Working Group on Sarcopenia and FNIH consensus may be up to 30% higher after correction for ECW excess. This correction improves the correlation between muscle mass and strength. The presented technology will facilitate, on a large scale, screening for sarcopenia, help identify mechanisms and improve understanding of clinical outcomes.

Measurement of aortofemoral volume wave velocity during the routine 12-channel ECG: relation to age, physiological hemoglobin A 1C, triglycerides and SBP in healthy individuals

OBJECTIVE

Measurements of pulse wave velocity are generally thought to be too impractical for clinical routine. This study aimed to develop a method that can be performed during routine 12-channel ECG.

METHODS

A 12-channel ECG simultaneously supplies arterial impedance plethysmographic signals from the extremities beside segmental multifrequency impedance measurements for obtaining body composition. The origin of the plethysmographic signal (volume wave) at the arms and legs was determined at the level of the elbows and the knees. The volume wave velocity (VWV) at the aorta and femoral arteries was calculated from the time difference of the plethysmographic signals between arms and legs.

RESULTS

Automated measurement of VWV was highly reproducible (r = 0.96). In 107 participants in perfect health, VWV in different models was positively related to age, physiological hemoglobin A 1C, triglycerides, normal standardized unattended blood pressure, but not to physiological low-density lipoprotein-cholesterol and high-density lipoprotein-cholesterol. Aortofemoral VWV was significantly higher in patients with established coronary artery disease than in healthy controls of the same age group (18.1 ± 5.8 vs. 11.9 ± 1.7 m/s, P < 0.001). VWV in study participants was higher than tonometrically determined pulse wave velocity as muscular arteries are included (13.2 ± 5.81 vs. 8.8 ± 2.98 m/s, n = 115, P < 0.001).

CONCLUSION

These background arterial impedance plethysmographic measurements for the measurement of VWV made simultaneously during 12-channel ECG show promise for large-scale, routine clinical assessment of large artery function.

Virological fitness of HIV in patients with resistance to enfuvirtide

Resistance to the HIV fusion inhibitor enfuvirtide is associated with mutations in the first heptad repeat region of gp41, but little is known of their impact on replicative fitness in vivo. We followed seven patients undergoing salvage therapy that included enfuvirtide in order to document the temporal generation of genotypic and phenotypic resistance in parallel with replicative fitness. Resistance to enfuvirtide was not associated with decreased replicative fitness of HIV strains infecting these patients.

Correlation between a phenotypic assay and three bioinformatic tools for determining HIV co-receptor use

The predictive value of three genotypic methods to determine HIV-1 co-receptor usage was assessed in 83 plasma specimens taking as reference the results obtained using a recombinant phenotypic assay (Phenoscript). The best concordance was found for webPSSM, followed by geno2pheno and wetcat (85.9, 71.8 and 70.5%, respectively). Less than 5.1% of phenotypic X4 viruses were missed by genotypic tools. The genotypic prediction of HIV-1 co-receptor usage can thus assist therapeutic decisions for using CCR5 antagonists.

Genetic and phenotypic features of blood and genital viral populations of clinically asymptomatic and antiretroviral-treatment-naive clade a human immunodeficiency virus type 1-infected women

In the present study, we assessed whether human immunodeficiency virus type 1 (HIV-1) genetic compartmentalization was associated with phenotypic CCR5 (R5) or CXCR4 (X4) coreceptor usage differences between the systemic and the genital viral populations. Four clinically asymptomatic and treatment-naïve clade A HIV-1-infected patients were selected from a cohort of 274 African women, because they were free of all the biological cofactors known to modify the kinetics of viral production in the genital tract. HIV RNA envelope sequences (V1 to V3) derived from plasma and cervicovaginal secretions (CVS) were amplified, subcloned, and sequenced. CCR5 or CXCR4 coreceptor usage was determined by production of recombinant viral particles, followed by single-cycle infection assays of indicator cell lines, using the tropism recombinant test. In these four selected patients, CVS-derived sequences appeared to be genetically distinct from blood-derived sequences (P < or = 0.001). Two patients were found to harbor virus populations with only the R5 phenotype in both compartments, whereas viruses using CXCR4 in addition to CCR5 were detected in two other patients. In particular, one woman harbored genital virus populations with mixed R5 and X4 phenotypes associated with peripheral blood populations with only the R5 phenotype. These results demonstrate genetic compartmentalization of HIV between the plasma and genital secretions of clinically asymptomatic, treatment-naïve, clade A-infected women. Also, for one patient, we report phenotypic coreceptor usage differences between the systemic (R5) and genital (R5/X4) viral populations. These features may be critical for the development of further mucosal vaccines, therapies, or new preventive strategies to block heterosexual transmission.

Determining human immunodeficiency virus coreceptor use in a clinical setting: degree of correlation between two phenotypic assays and a bioinformatic model

Two recombinant phenotypic assays for human immunodeficiency virus (HIV) coreceptor usage and an HIV envelope genotypic predictor were employed on a set of clinically derived HIV type 1 (HIV-1) samples in order to evaluate the concordance between measures. Previously genotyped HIV-1 samples derived from antiretroviral-naïve individuals were tested for coreceptor usage using two independent phenotyping methods. Phenotypes were determined by validated recombinant assays that incorporate either an approximately 2,500-bp ("Trofile" assay) or an approximately 900-bp (TRT assay) fragment of the HIV envelope gp120. Population-based HIV envelope V3 loop sequences ( approximately 105 bp) were derived by automated sequence analysis. Genotypic coreceptor predictions were performed using a support vector machine model trained on a separate genotype-Trofile phenotype data set. HIV coreceptor usage was obtained from both phenotypic assays for 74 samples, with an overall 85.1% concordance. There was no evidence of a difference in sensitivity between the two phenotypic assays. A bioinformatic algorithm based on a support vector machine using HIV V3 genotype data was able to achieve 86.5% and 79.7% concordance with the Trofile and TRT assays, respectively, approaching the degree of agreement between the two phenotype assays. In most cases, the phenotype assays and the bioinformatic approach gave similar results. However, in cases where there were differences in the tropism results, it was not clear which of the assays was "correct." X4 (CXCR4-using) minority species in clinically derived samples likely complicate the interpretation of both phenotypic and genotypic assessments of HIV tropism.

Human immunodeficiency virus type 1 variants isolated from single plasma samples display a wide spectrum of neutralization sensitivity

Individuals infected with human immunodeficiency virus type 1 (HIV-1) harbor a mixture of viral variants with different sequences and in some instances with different phenotypic properties. Major and rapid fluctuations in the proportion of viral variants coexisting in an infected individual can be observed under strong pharmacological and immune selective pressure. Because of the short half-life of HIV-infected cells and of HIV virions in the blood, plasma virus populations are highly relevant to HIV evolution in the face of these selective pressures. Here we analyzed the sensitivity to antibody-mediated neutralization of viral variants coexisting in the plasma virus populations of two infected patients. For each patient, several replication-competent viral clones were constructed that carry primary envelope gene sequences obtained from a single plasma sample. Viral clones differed in their tropism and replicative capacity and in the number and positions of glycosylation sites in the envelope glycoproteins. Viruses were tested against heterologous and autologous sera obtained at different time points. Interestingly, we found that viral variants coexisting in each plasma sample were highly heterogeneous in terms of sensitivity to neutralization. The order of sensitivity depended on the serum used and was not associated with virus tropism. The neutralization potency of sera increased with the duration of the infection for both autologous and heterologous neutralization.

Covert human immunodeficiency virus replication in dendritic cells and in DC-SIGN-expressing cells promotes long-term transmission to lymphocytes

HIV-1 virions are efficiently captured by monocyte-derived immature dendritic cells (iDCs), as well as by cell lines expressing the lectin DC-SIGN. Viral infectivity can be retained for several days, and even enhanced, before transmission to CD4+ lymphocytes. The role of DC-SIGN in viral retention and enhancement of infection is not fully understood and varies according to the cell line expressing the lectin. We studied here the mechanisms underlying this process. We focused our study on X4-tropic human immunodeficiency virus (HIV) strains, since they were widely believed not to replicate in iDCs. However, we first show that X4 HIV replicates covertly and slowly in iDCs. This is also the case in Raji-DC-SIGN cells, which are classically used to study HIV transmission. We used either single-cycle or replicative HIV and measured viral RT and replication to further demonstrate that transfer of incoming virions from iDCs or DC-SIGN+ cells occurs only on the short-term (i.e., a few hours after viral exposure). There is no long-term storage of original HIV particles in these cells. A few days after viral exposure, replicative viruses, and not single-cycle virions, are transmitted to CD4+ cells. The cell-type-dependent activity of DC-SIGN reflects the ability of HIV to replicate covertly in some cells, and not in others.

Impact of antiretroviral treatment on the tropism of HIV-1 plasma virus populations

OBJECTIVE

To study the impact of antiretroviral therapy on the tropism of plasma HIV-1 virus populations during treatment response and virological escape.

DESIGN

To investigate whether the selective pressure exerted by antiretroviral treatment influences the tropism of the plasma virus populations, we retrospectively determined the co-receptor usage of viruses present in plasma samples obtained before and at varying intervals after starting antiviral therapy.

METHODS

The co-receptor usage of plasma virus was determined using our recently published tropism recombinant test (V. Trouplin et al., J Virol, 2001; 75:251-259). This assay relies on virus production by homologous recombination between a plasmid encoding the entire HIV genome except for a deletion of the major tropism determinant, and a polymerase chain reaction (PCR) product spanning this region and the adjoining flanking sequences, obtained by reverse transcriptase (RT)-PCR amplification of viral RNA from the patient's plasma.

RESULTS

Twenty-four of the 32 patients analysed harboured exclusively R5 virus in plasma before the initiation of treatment, whereas eight had mixed R5/X4 virus populations. In four of these eight patients, all of whom initially responded to treatment, the persistence of R5 virus in plasma was observed, whereas the X4 component of the virus population became undetectable. The suppression of the X4 virus component was a transient phenomenon and variants able to use CXCR4 re-emerged after a variable delay.

CONCLUSIONS

The impact of therapy on virus populations differs according to virus tropism. Differences in target cell populations, tissue distribution and replication characteristics between R5 and X4 viruses could explain the preferential suppression of X4 virus.

Baseline susceptibility of primary human immunodeficiency virus type 1 to entry inhibitors

Human immunodeficiency virus type 1 plasma viruses from 29 entry inhibitor-naive patients were characterized for their susceptibilities to T-20, AMD3100, and RANTES. A strikingly wide range of susceptibilities to T-20 was observed that was influenced by coreceptor usage but not by the susceptibilities of the viruses to inhibitors that target the chemokine receptors or by polymorphisms in the gp41 N helix.

Deletion of the 19kDa antigen does not alter the protective efficacy of BCG

Expression of the Mycobacterium tuberculosis 19kDa lipoprotein in saprophytic mycobacteria has been found to reduce their ability to prime a protective response to subsequent virulent challenge in the mouse model. The present study was designed to test whether 19kDa expression has an analogous detrimental effect on the efficacy of BCG vaccination. In contrast to the results in saprophytes, neither overexpression of the 19kDa antigen, nor deletion of the endogenous 19kDa gene altered the ability of BCG to protect against M. tuberculosis challenge in a mouse model.

Hyperthyroidism due to a TSH secreting pituitary adenoma: case report, treatment and evidence for adenoma TSH by morphological and cell culture studies

A 36-year-old woman with recurrent hyperthyroidism, inappropriately elevated serum TSH, and an 8 mm pituitary microadenoma is described. Transsphenoidal adenomectomy rapidly reduced serum TSH to normal and restored the euthyroid state with retention of other anterior pituitary functions. Tissue removed at operation was examined by light and electron microscopy and cell culture. The tissue was neoplastic, composed of irregular often elongated cells which immunostrained positively only with antisera to beta-TSH. The cells contained small granules (100-170 nm) usually along the cell membrane. In cell culture TSH alone was secreted and the rate of secretion declined with time. We conclude that the patient had a TSH secreting microadenoma as a cause of her hyperthyroidism.