Low biochemical nutritional parameters in acutely ill hospitalized elderly patients with and without stage III to IV pressure ulcers

Background and aims: Pressure ulcers are associated with impaired nutritional status in acutely ill elderly patients. The objective of this study was to establish whether a difference exists between biochemical nutritional parameters in acutely ill elderly with stage III to IV pressure ulcers and a group of acutely ill elderly with no pressure ulcers. Methods: In a retrospective study we compared 8 biochemical nutritional markers in a group of 22 acutely ill elderly patients consecutively admitted to the geriatric ward who had stage III to IV pressure ulcers (PU group) in addition to their acute illness with a control group of 40 acutely ill elderly patients with no pressure ulcers (NPU group). Results: The PU group compared with the NPU group had significantly lower (p<0.0001) values of albumin, transferrin, hemoglobin, cholesterol, iron, and zinc (p<0.0059). Total lymphocyte count was slightly, but not significantly lower in the PU group. In contrast, C-Reactive Protein levels were significantly higher (p<0.0001) in the PU group compared with the NPU group, indicating a more severe illness in the presence of additional pressure ulcers. Conclusions: In this study, serum levels of biochemical nutritional parameters in acutely ill elderly patients with stage III to IV pressure ulcers are lower than those of acutely ill elderly subjects with no pressure ulcers, indicating a worse nutritional status of the PU patients. These findings, while not documenting a causal relationship, suggest the need for routine nutritional assessment and support in older patients, especially those with pressure ulcer

Fumarate Reductase Activity Maintains an Energized Membrane in Anaerobic Mycobacterium tuberculosis

Oxygen depletion of Mycobacterium tuberculosis engages the DosR regulon that coordinates an overall down-regulation of metabolism while up-regulating specific genes involved in respiration and central metabolism. We have developed a chemostat model of M. tuberculosis where growth rate was a function of dissolved oxygen concentration to analyze metabolic adaptation to hypoxia. A drop in dissolved oxygen concentration from 50 mmHg to 0.42 mmHg led to a 2.3 fold decrease in intracellular ATP levels with an almost 70-fold increase in the ratio of NADH/NAD+. This suggests that re-oxidation of this co-factor becomes limiting in the absence of a terminal electron acceptor. Upon oxygen limitation genes involved in the reverse TCA cycle were upregulated and this upregulation was associated with a significant accumulation of succinate in the extracellular milieu. We confirmed that this succinate was produced by a reversal of the TCA cycle towards the non-oxidative direction with net CO2 incorporation by analysis of the isotopomers of secreted succinate after feeding stable isotope (13C) labeled precursors. This showed that the resulting succinate retained both carbons lost during oxidative operation of the TCA cycle. Metabolomic analyses of all glycolytic and TCA cycle intermediates from 13C-glucose fed cells under aerobic and anaerobic conditions showed a clear reversal of isotope labeling patterns accompanying the switch from normoxic to anoxic conditions. M. tuberculosis encodes three potential succinate-producing enzymes including a canonical fumarate reductase which was highly upregulated under hypoxia. Knockout of frd, however, failed to reduce succinate accumulation and gene expression studies revealed a compensatory upregulation of two homologous enzymes. These major realignments of central metabolism are consistent with a model of oxygen-induced stasis in which an energized membrane is maintained by coupling the reductive branch of the TCA cycle to succinate secretion. This fermentative process may offer unique targets for the treatment of latent tuberculosis

Childhood tuberculosis is associated with decreased abundance of T cell gene transcripts and impaired T cell function

The WHO estimates around a million children contract tuberculosis (TB) annually with over 80 000 deaths from dissemination of infection outside of the lungs. The insidious onset and association with skin test anergy suggests failure of the immune system to both recognise and respond to infection. To understand the immune mechanisms, we studied genome-wide whole blood RNA expression in children with TB meningitis (TBM). Findings were validated in a second cohort of children with TBM and pulmonary TB (PTB), and functional T-cell responses studied in a third cohort of children with TBM, other extrapulmonary TB (EPTB) and PTB. The predominant RNA transcriptional response in children with TBM was decreased abundance of multiple genes, with 140/204 (68%) of all differentially regulated genes showing reduced abundance compared to healthy controls. Findings were validated in a second cohort with concordance of the direction of differential expression in both TBM (r2 = 0.78 p = 2x10-16) and PTB patients (r2 = 0.71 p = 2x10-16) when compared to a second group of healthy controls. Although the direction of expression of these significant genes was similar in the PTB patients, the magnitude of differential transcript abundance was less in PTB than in TBM. The majority of genes were involved in activation of leucocytes (p = 2.67E-11) and T-cell receptor signalling (p = 6.56E-07). Less abundant gene expression in immune cells was associated with a functional defect in T-cell proliferation that recovered after full TB treatment (p<0.0003). Multiple genes involved in T-cell activation show decreased abundance in children with acute TB, who also have impaired functional T-cell responses. Our data suggest that childhood TB is associated with an acquired immune defect, potentially resulting in failure to contain the pathogen. Elucidation of the mechanism causing the immune paresis may identify new treatment and prevention strategies

13C Metabolic Flux Analysis Identifies an Unusual Route for Pyruvate Dissimilation in Mycobacteria which Requires Isocitrate Lyase and Carbon Dioxide Fixation

Mycobacterium tuberculosis requires the enzyme isocitrate lyase (ICL) for growth and virulence in vivo. The demonstration that M. tuberculosis also requires ICL for survival during nutrient starvation and has a role during steady state growth in a glycerol limited chemostat indicates a function for this enzyme which extends beyond fat metabolism. As isocitrate lyase is a potential drug target elucidating the role of this enzyme is of importance; however, the role of isocitrate lyase has never been investigated at the level of in vivo fluxes. Here we show that deletion of one of the two icl genes impairs the replication of Mycobacterium bovis BCG at slow growth rate in a carbon limited chemostat. In order to further understand the role of isocitrate lyase in the central metabolism of mycobacteria the effect of growth rate on the in vivo fluxes was studied for the first time using 13C-metabolic flux analysis (MFA). Tracer experiments were performed with steady state chemostat cultures of BCG or M. tuberculosis supplied with 13C labeled glycerol or sodium bicarbonate. Through measurements of the 13C isotopomer labeling patterns in protein-derived amino acids and enzymatic activity assays we have identified the activity of a novel pathway for pyruvate dissimilation. We named this the GAS pathway because it utilizes the Glyoxylate shunt and Anapleurotic reactions for oxidation of pyruvate, and Succinyl CoA synthetase for the generation of succinyl CoA combined with a very low flux through the succinate – oxaloacetate segment of the tricarboxylic acid cycle. We confirm that M. tuberculosis can fix carbon from CO2 into biomass. As the human host is abundant in CO2 this finding requires further investigation in vivo as CO2 fixation may provide a point of vulnerability that could be targeted with novel drugs. This study also provides a platform for further studies into the metabolism of M. tuberculosis using 13C-MFA

Mycobacteria counteract a TLR-mediated nitrosative defense mechanism in a zebrafish infection model.

Pulmonary tuberculosis (TB), caused by the intracellular bacterial pathogen Mycobacterium tuberculosis (Mtb), is a major world health problem. The production of reactive nitrogen species (RNS) is a potent cytostatic and cytotoxic defense mechanism against intracellular pathogens. Nevertheless, the protective role of RNS during Mtb infection remains controversial. Here we use an anti-nitrotyrosine antibody as a readout to study nitration output by the zebrafish host during early mycobacterial pathogenesis. We found that recognition of Mycobacterium marinum, a close relative of Mtb, was sufficient to induce a nitrosative defense mechanism in a manner dependent on MyD88, the central adaptor protein in Toll like receptor (TLR) mediated pathogen recognition. However, this host response was attenuated by mycobacteria via a virulence mechanism independent of the well-characterized RD1 virulence locus. Our results indicate a mechanism of pathogenic mycobacteria to circumvent host defense in vivo. Shifting the balance of host-pathogen interactions in favor of the host by targeting this virulence mechanism may help to alleviate the problem of infection with Mtb strains that are resistant to multiple drug treatments

Knuckle pads – a rare finding

Knuckle pads are rare harmless subcutaneous nodules that must be differentiated from joint disease of the proximal interphalangeal or rarely of the metacarpophalangeal joints as well as from other masses of the paraarticular tissues. We present a case of an otherwise healthy 36-year-old woman presenting with bilateral knuckle pads located at the dorsal aspect of the proximal interphalangeal joints. No predisposition to a specific musculoskeletal disorder was noted. Ultrasound revealed well-delimited subcutaneous hypoechoic masses without internal flow signals at color Doppler. Histology showed proliferation of myofibroblasts with a decrease of elastic filaments in the deep dermis. The clinical picture, the family history in addition to the histology allowed us to make the diagnosis of knuckle pads. We present the ultrasound findings of knuckle pads and discuss the differential diagnosis of a “swelling” in the dorsal region of proximal interphalangeal joints and metacarpophalangeal joints.Palce poduszeczkowate (knuckle pads), potocznie zwane guzkami kłykciowymi, są rzadkimi i łagodnymi zmianami podskórnymi, które należy różnicować z chorobą stawu międzypaliczkowego bliższego i, rzadziej, stawu śródręczno‑paliczkowego,a także z innymi masami/zmianami okołostawowymi. Prezentujemy przypadek 36‑letniej zdrowej kobiety, u której stwierdzono obustronne guzki zlokalizowane po stronie grzbietowej stawów międzypaliczkowych bliższych. Badanie ultrasonograficzne wykazało wyraźnie odgraniczone, hipoechogeniczne guzki zlokalizowane podskórnie, bez cech obecności nieprawidłowego unaczynienia w badaniu kolorowym dopplerem. W badaniu histopatologicznym ujawniono proliferację miofibroblastów oraz zmniejszenie liczby włókien elastycznych w głębokich warstwach skóry właściwej. Obraz kliniczny, wywiad rodzinny oraz badania histologiczne pomogły w ustaleniu rozpoznania. W artykule przedstawiamy ultrasonograficzny obraz palców poduszeczkowatych oraz diagnostykę różnicową pogrubienia tkanek miękkich okolicy grzbietowej stawów międzypaliczkowego bliższego i śródręczno‑paliczkowego

Change from subcutaneous to intravenous abatacept and back in patients with rheumatoid arthritis as simulation of a vacation: a prospective phase IV, open-label trial (A-BREAK).

BACKGROUND Vacation can present a major problem to patients with rheumatoid arthritis (RA) treated with weekly subcutaneous biologics, including subcutaneous (SC) abatacept. Therefore, the replacement of four SC doses of abatacept by a single dose of intravenous (IV) abatacept may present an acceptable alternative to cover a 4-week interval needed for vacations. In the study presented, we analyzed the efficacy and safety of this intervention followed by a switch back to SC abatacept after 4 weeks. METHOD This open-label, prospective, single-arm, 24-week trial recruited patients with established RA in low disease activity (LDA) or in remission on treatment with SC abatacept for at least 3 months to receive a single dose of IV abatacept (baseline) followed by a break of 4 weeks and then continuation of weekly SC abatacept from day 28 on. Disease-modifying anti-rheumatic drug (DMARD)-inadequate or biologic-inadequate responders (or both) were included. RESULTS The baseline characteristics of the 49 patients (per protocol) were typical for a cohort of RA patients with established disease (mean disease duration of 8.31 years) in LDA under treatment with synthetic DMARDs and a biologic. Two patients (one flare and one patient decision) dropped out of the study. The proportions of patients with disease activity score in 28 joints (DAS-28) of not more than 3.2 at day 28 were 93.9 % (95 % confidence interval (CI) 83.5-97.9) and 93.6 % (95 % CI 82.8-97.8) at the end of the study (day 168). The average DAS-28 values were 1.74 (standard deviation (SD) ± 0.72) at baseline, 2.03 (SD ± 1.03) at day 28, and 1.96 (SD ± 0.92) at the end of the study (day 168). Pre-exposure to IV abatacept and having failed methotrexate or anti-tumor necrosis factor (anti-TNF) did not influence the average DAS-28 or the proportion of patients maintaining LDA over time. The average health assessment questionnaire disability index (HAQ-DI) was stable throughout the study. Adverse events (AEs) occurred in 75 % of subjects. Four serious AEs were described during the study. None of them was related to the investigational product, and all serious AEs could be resolved during hospitalization. CONCLUSION This prospective, open-label study of abatacept shows for the first time that switching from weekly SC to IV abatacept and back after 4 weeks is an effective and safe way to bridge vacations in RA patients in LDA or remission. (NCT1846975, registered April 19, 2013.)

Integration of Metabolomics and Transcriptomics Reveals a Complex Diet of Mycobacterium tuberculosis during Early Macrophage Infection

Nutrient acquisition from the host environment is crucial for the survival of intracellular pathogens, but conceptual and technical challenges limit our knowledge of pathogen diets. To overcome some of these technical roadblocks, we exploited an experimentally accessible model for early infection of human macrophages by Mycobacterium tuberculosis, the etiological agent of tuberculosis, to study host-pathogen interactions with a multi-omics approach. We collected metabolomics and complete transcriptome RNA sequencing (dual RNA-seq) data of the infected macrophages, integrated them in a genome-wide reaction pair network, and identified metabolic subnetworks in host cells and M. tuberculosis that are modularly regulated during infection. Up- and downregulation of these metabolic subnetworks suggested that the pathogen utilizes a wide range of host-derived compounds, concomitant with the measured metabolic and transcriptional changes in both bacteria and host. To quantify metabolic interactions between the host and intracellular pathogen, we used a combined genome-scale model of macrophage and M. tuberculosis metabolism constrained by the dual RNA-seq data. Metabolic flux balance analysis predicted coutilization of a total of 33 different carbon sources and enabled us to distinguish between the pathogen’s substrates directly used as biomass precursors and the ones further metabolized to gain energy or to synthesize building blocks. This multiple-substrate fueling confers high robustness to interventions with the pathogen’s metabolism. The presented approach combining multi-omics data as a starting point to simulate system-wide host-pathogen metabolic interactions is a useful tool to better understand the intracellular lifestyle of pathogens and their metabolic robustness and resistance to metabolic interventions.ISSN:2379-507