Impact of rifampicin dose in bone and joint prosthetic device infections due to Staphylococcus spp: a retrospective single-center study in France.

BACKGROUND: Prosthetic joint infections (PJI) are a major cause of morbidity and mortality burden worldwide. While surgical management is well defined, rifampicin (RIF) dose remains controversial. The aim of our study was to determine whether Rifampicin dose impact infection outcomes in PJI due to Staphylococcus spp. METHODS: single-center retrospective study including 411 patients with PJI due to Rifampicin-sensitive Staphylococcus spp. Rifampicine dose was categorized as follow: < 10 mg/kg/day, 10-20 mg/kg/day or > 20 mg/kg/day. The primary endpoint was patient recovery, defined as being free of infection during 12 months after the end of the initial antibiotic course. RESULTS: 321 (78%) received RIF for the full antibiotic course. RIF dose didn't affect patients recovery rate with 67, 76 and 69% in the < 10, 10-20 and > 20 mg/kg/day groups, respectively (p = 0.083). In univariate analysis, recovery rate was significantly associated with gender (p = 0.012) but not to RIF dose, or Staphylococcus phenotype (aureus or coagulase-negative). In multivariate analysis, age (p = 0.01) and treatment duration (p <  0.01) were significantly associated with recovery rate. CONCLUSION: These data suggest that lower doses of RIF are as efficient and safe as the recommended high-dose French regimen in the treatment of PJI.

Kinetics of SARS-CoV-2-Neutralising Antibodies of Residents of Long-Term Care Facilities.

INTRODUCTION: Elderly residents of nursing homes (NHs) and long-term care units (LTCUs) have been shown to have a high risk of mortality and morbidity in cases of SARS-CoV-2 infection. The objective of this study was to examine the kinetics of neutralizing antibodies (NAbs) directed against the SARS-CoV-2 virus in residents of the NH and LTCU units of our University Hospital who were identified with positive serology after the first epidemic outbreak. MATERIALS AND METHODS: The participants included were sampled every three months for qualitative serological testing, as well as quantitative testing by neutralization tests using retroviral particles containing the S glycoprotein of SARS-CoV-2. Vaccination using the Comirnaty (Pfizer BNT162b2) vaccine begun before the last serological follow-up. RESULTS: The median NAb titer in June 2020 was 80 [40; 60] versus 40 [40; 160] three months later, showing a statistically significant decline (p < 0.007), but remained stable between the three- and six-month timepoints (p = 0.867). By nine months after vaccination, we observed a significant difference between vaccinated residents known to have positive serology before vaccination (SERO+, Vacc+) and those vaccinated without having previously shown COVID-19 seroconversion (SERO-, Vacc+), the latter group showing similar titers to the SERO+, Vacc- participants (p=0.166). The median antibody titer in SERO+, Vacc+ patients increased 15-fold following vaccination. DISCUSSION: Humoral immunity against SARS-CoV-2 appears to be persistent in elderly institutionalized patients, with a good post-vaccination response by residents who had already shown seroconversion but a notably diminished response by those who were seronegative before vaccination. To evaluate immunity in its entirety and elaborate a sound vaccination strategy, the cellular immune response via T cells specific to SARS-CoV-2 merits analysis, as this response is susceptible to being affected by immunosenescence.

Serum procalcitonin does not differentiate between infection and disease flare in patients with systemic lupus erythematosus.

Systemic erythematosus lupus (SLE) is a common autoimmune disease. Disease flares may mimic infection with fever, inflammatory syndrome and chills, sometimes resulting in a difficult differential diagnosis. Elevated serum procalcitonin (PCT) levels have been reported to be predictive of bacterial infections, but with conflicting results. The value of serum procalcitonin has not been assessed in large series of SLE. We aimed to describe the distribution of PCT levels in SLE patients with and without flares, to assess the factors associated with increased PCT levels, and to determine the positive and negative predictive values of increased PCT for bacterial infection in SLE patients. Hospitalized SLE patients were included in a retrospective study. Serum PCT had been assayed, or a serum sample had been frozen on admission, before treatment modification. Serum PCT, measured by an automated immunofluorometric assay, and SLEDAI were assessed at the same time. Some 53 women (median age: 33.7 years, range 16-76) and seven men (median age: 52.5 years ± 19) were included. The median SLEDAI for patients with flare (n = 16, 28%) was 2 (range: 0-29). Five patients (8%) had systemic infection. Only one patient had increased PCT levels. Men had significantly higher PCT levels than women (0.196 ± 0.23 versus 0.066 ± 0.03, p < 0.01) and a significant correlation was observed between PCT, age, erythrocyte sedimentation rate, and C-reactive protein. We conclude that PCT levels were within the normal range in infected and non-infected SLE patients and there was no ability to differentiate SLE patients with or without bacterial infection.

Medical versus surgical treatment in native hip and knee septic arthritis.

OBJECTIVE: Antibiotic treatment and arthroscopic or open drainage is the gold standard for septic arthritis. Full recovery takes time after surgery and hospital stay is longer than for arthrocentesis at the bedside. We aimed to evaluate the effectiveness of arthrocentesis (medical approach) versus a surgical approach. METHOD: We retrospectively included 97 cases of native joint arthritis (hip and knee) between 2010 and 2017. The primary outcome was treatment failure of medical and surgical approaches (defined as surgical intervention within 7 days following diagnosis). Risk factors of failure were identified by univariable and multivariable logistic regression. RESULTS: We included 72 cases of knee arthritis, of which 43 and 29 were treated medically and surgically, respectively; 25 cases of hip arthritis, of which 8 and 17 were treated medically and surgically, respectively. Failure was observed in 39.2% of cases in the medical group and in 30.4% in the surgical group (P=0.2) (37.5% vs. 52.9% and 39.5% vs. 17.2% for hip and knee, respectively). The univariate analysis identified age and male sex as risk factors for failure (P=0.048 and P=0.02, respectively), but only age was independently associated with failure (P=0.04). Hospital length of stay was 12 days shorter in the medical group (21 vs. 33 days, P=0.02), sequelae were less frequent and less important in the medical group (31.7% vs. 60%). CONCLUSION: The medical treatment seems to be as effective as the surgical treatment for native joint septic arthritis with a shorter hospital stay and better functional outcome. Further prospective studies are warranted.

C-myc-induced apoptosis in polycystic kidney disease is Bcl-2 and p53 independent.

The SBM mouse is a unique transgenic model of polycystic kidney disease (PKD) induced by the dysregulated expression of c-myc in renal tissue. In situ hybridization analysis demonstrated intense signal for the c-myc transgene overlying tubular cystic epithelium in SBM mice. Renal proliferation index in SBM kidneys was 10-fold increased over nontransgenic controls correlating with the presence of epithelial hyperplasia. The specificity of c-myc for the proliferative potential of epithelial cells was demonstrated by substitution of c-myc with the proto-oncogene c-fos or the transforming growth factor (TGF)-alpha within the same construct. No renal abnormalities were detected in 13 transgenic lines established, indicating that the PKD phenotype is dependent on functions specific to c-myc. We also investigated another well characterized function of c-myc, the regulation of apoptosis through pathways involving p53 and members of the bcl-2 family, which induce and inhibit apoptosis, respectively. The SBM kidney tissues, which overexpress c-myc, displayed a markedly elevated (10-100-fold) apoptotic index. However, no significant difference in bcl-2, bax, or p53 expression was observed in SBM kidney compared with controls. Direct proof that the heightened renal cellular apoptosis in PKD is not occurring through p53 was obtained by successive matings between SBM and p53(-/-) mice. All SBM offspring, irrespective of their p53 genotype, developed PKD with increased renal epithelial apoptotic index. In addition, overexpression of both bcl-2 and c-myc in double transgenic mice (SBB+/SBM+) also produced a similar PKD phenotype with a high apoptotic rate, showing that c-myc can bypass bcl-2 in vivo. Thus, the in vivo c-myc apoptotic pathway in SBM mice occurs through a p53- and bcl-2-independent mechanism. We conclude that the pathogenesis of PKD is c-myc specific and involves a critical imbalance between the opposing processes of cell proliferation and apoptosis.

Sorting of Golgi resident proteins into different subpopulations of COPI vesicles: a role for ArfGAP1.

We present evidence for two subpopulations of coatomer protein I vesicles, both containing high amounts of Golgi resident proteins but only minor amounts of anterograde cargo. Early Golgi proteins p24alpha2, beta1, delta1, and gamma3 are shown to be sorted together into vesicles that are distinct from those containing mannosidase II, a glycosidase of the medial Golgi stack, and GS28, a SNARE protein of the Golgi stack. Sorting into each vesicle population is Arf-1 and GTP hydrolysis dependent and is inhibited by aluminum and beryllium fluoride. Using synthetic peptides, we find that the cytoplasmic domain of p24beta1 can bind Arf GTPase-activating protein (GAP)1 and cause direct inhibition of ArfGAP1-mediated GTP hydrolysis on Arf-1 bound to liposomes and Golgi membranes. We propose a two-stage reaction to explain how GTP hydrolysis constitutes a prerequisite for sorting of resident proteins, yet becomes inhibited in their presence.

Action of spontaneously produced beta interferon in differentiation of embryonal carcinoma cells through an autoinduction mechanism.

In the current study, we have addressed the role of interferons (IFNs) in controlling the differentiation of pluripotent P19 embryonal carcinoma (EC) cells. Blocking IFN activity in the culture medium of differentiating cells with antibodies leads to a strong decrease in the degree of differentiation. The antibodies are active for a relatively short time. During this time, IFN-beta mRNA can be detected in the differentiating cells, as can increases of IFN stimulation response element-binding activity and NF-KB. The timing of IFN action also coincides with the accumulation of cytoplasmic double-stranded RNA (dsRNA) and with a drop in dsRNA unwindase-modificase activity. A model for the involvement of autoinduction of IFN by intracellular dsRNA in the control of differentiation in this system is presented.

Overproduction of NFKB2 (lyt-10) and c-Rel: a mechanism for HTLV-I Tax-mediated trans-activation via the NF-kappa B signalling pathway.

Molecular, biochemical and epidemiological evidence implicate HTLV-I as an etiologic agent of adult T cell leukemia (ATL). The Tax protein of HTLV-I, a positive transcriptional activator of HTLV-I gene expression, is a viral oncogene that also increases transcription of cellular genes including GM-CSF, IL-2R alpha and IL-2. One of the cellular targets of the trans-activating effects of Tax is the NF-kappa B/Rel family of transcription factors, pleiotropic regulators of immunoregulatory, cytokine and viral gene expression. In this report, we demonstrate that NFKB2 (lyt-10) and c-Rel are overexpressed in HTLV-I infected and Tax-expressing cells and, together, account for the majority of the constitutive NF-kappa B binding activity in these cells before and after PMA stimulation. Most importantly, we show a Tax-dependent correlation between expression of NFKB2(p100) and processing to the DNA binding NFKB2(p52) form, induction of c-Rel, and trans-activation of NF-kappa B-mediated gene expression. Furthermore, the NFKB2 precursor is physically associated with c-Rel and with Tax in HTLV-I infected cells. We propose that NFKB2 synthesis and processing allows continuous nuclear expression of an otherwise cytoplasmic protein and, in conjunction with overexpression of c-Rel, NFKB2 alters the NF-kappa B signalling pathway and contributes to leukemic transformation of T cells by HTLV-I.

Dysregulation of cellular proliferation and apoptosis mediates human autosomal dominant polycystic kidney disease (ADPKD).

The proto-oncogene c-myc has been implicated in both cellular proliferation and apoptosis, and we have shown that overexpression of c-myc can induce polycystic kidney disease in transgenic mice. To elucidate the molecular and cellular defects underlying cystogenesis, we have investigated the potential roles of cell proliferation and apoptosis as they relate to c-myc and modulators of c-myc function in human autosomal dominant polycystic kidney disease (ADPKD). Renal c-myc expression was consistently elevated, up to 15-fold, in ADPKD. High levels of c-myc expression correlated with 10- to 100-fold increased proliferation index in cystic epithelium. Interestingly, steady-state levels of bcl-2 mRNA were also increased up to 20-fold and Bcl-2 protein was markedly elevated. In contrast, the expression of bax and p53 was virtually unchanged. However, apoptosis was consistently and significantly increased in ADPKD kidneys, unchecked by high levels of Bcl-2. Together with proliferation, apoptosis may thus represent a general mechanism for cyst growth and tissue remodeling. We conclude that both epithelial cell proliferation and apoptosis required for normal kidney homeostasis are deregulated in ADPKD, recapitulating the renal developmental program. Furthermore, abnormal expression of proto-oncogenes regulating these processes is an important mediator of cystogenesis in human ADPKD.

Wild-type egr1/Krox24 promotes and dominant-negative mutants inhibit, pluripotent differentiation of p19 embryonal carcinoma cells.

The zinc-finger transcription factor Krox24 was analysed for its role in differentiation in P19 embryonal carcinoma cells. Reciprocal dominant negative mutants consisting of Krox24 deleted for a crucial region of the zinc-finger domain (delta Krox24) or of the zinc-finger region alone (delta Krox24Zf) abolished the activation of transcription by Krox24 in P19 cells. Expression of Krox24 led to spontaneous differentiation of P19 cells in a lineage-independent fashion. Krox24 transfected populations, as well as individual clones randomly picked from them, displayed a wide array of diverse morphologies and expressed markers characteristic of a variety of differentiated cells. The dominant negative mutants blocked differentiation of P19 cells. We conclude that expression of Krox24 is sufficient for pluripotent differentiation of embryonal carcinoma cells, and that expression of Krox24 or other egr family members is essential to this process.

An enzymic analysis of a nuclear envelope fraction.

A rat liver nuclear envelope fraction isolated essentially by the technique of Monneron et al. (J. Cell Biol. 55, 104-125 (1972) is characterized by high levels of glucose-6-phosphatase and 5'-nucleotidase. A broadly specific nucleoside triphosphatase activity is present. Cytochromes b5 and P-450 as well as NADPH- and NADH-cytochrome c reductase activities are present but at lower levels than found in microsomes. Cytochrome c oxidase activity is low. RNA polymerase activity is absent from the nuclear envelope fraction. Cytochemistry shows that glucose-6-phosphatase activity is strong and restricted to the nuclear envelope of nuclei. 5'-Nucleotidase shows weak reaction deposit in whole nuclei but in contrast gives clear reaction deposit in isolated nuclear envelopes. Cytochemical reaction deposit due to nucleoside triphosphatase activity is not restricted to the nuclear envelope but is found to a larger extent within the nucleus.

Interactions between HTLV-I Tax and NF-kappa B/Rel proteins in T cells.

Members of the NF-kappa B/Rel family of transcription factors are involved in the transcriptional regulation of numerous polypeptides important to the immune response and cellular growth. Several genes regulated in part by NF-kappa B/Rel such as interleukin 2, IL-2 receptor alpha, and GM-CSF are trans-activated via an indirect association with the HTLV-I Tax protein in virus-infected and transformed T cells. In this study, we have investigated the interactions between Tax and NF-kappa B/Rel in an attempt to elucidate the mechanism of Tax mediated trans-activation and its role in leukemogenesis. Transfection studies were performed in Jurkat T cells using expression vectors for individual NF-kappa B subunits and the Tax protein as well as an NF-kappa B regulated reporter plasmid. NF-kappa B proteins differentially trans-activated the HIV-1 enhancer-CAT reporter; co-expression of Tax abrogated the inhibitory effect of I kappa B alpha and a trans-dominant negative mutant of p65 (p65 delta), indicating that Tax was a trans-dominant activator of NF-kappa B-regulated genes. Co-immunoprecipitation studies with extracts from transfected cells and NF-kappa B and Tax subunit specific antibodies revealed that Tax did not co-immunoprecipitate with p50/p105, c-Rel, or I kappa B; however, antibody specific to p65 was able to co-immunoprecipitate a 40kDa protein from Tax-transfected cells. Previous studies have demonstrated a physical interaction between Tax protein and p100, indicating that Tax may preferentially associate with specific NF-kappa B proteins.

Cytochemical analysis of the reconstitution of endoplasmic reticulum after microinjection of rat liver microsomes into Xenopus oocytes.

Fragments of rough and smooth endoplasmic reticulum purified from rat liver were injected into Xenopus oocyte cytoplasm. Light and electron microscopy, cytochemistry, immunocytochemistry, and enzyme assay were employed to determine the fate of heterologous membranes in the host cytoplasm. The in vivo-incubated microsomes disappeared in a time-dependent manner. Within 3 hr, rough microsomes were replaced by flattened ER cisternae and smooth microsomes were replaced by a network of anastomosing tubules. Polyclonal antibodies against rat liver microsomes and protein A-gold complexes were applied to glycol methacrylate sections of microinjected oocytes. Specific labeling was observed over discrete rough and smooth ER cisternae 3 hr after microinjection. Endogenous ER was not labeled by this technique, and label was not observed when sections were treated with pre-immune antibodies. Diaminobenzidene cytochemistry of microinjected rat lacrimal gland microsomes revealed enzyme activity in heterologous microsomes after 3 hr of in vivo incubation. Control injected microsomes (inactivated by heat denaturation) became associated with autophagic vacuoles, coincident with changes in lysosomal activity. Freshly isolated un-denatured microsomes did not provoke changes in lysosomal activity, and glucose-6-phosphatase activity associated with microinjected membranes could be detected 21 hr after in vivo incubation. Since rat liver microsomes reconstitute after in vivo incubation into cytoplasmic structures resembling those from which they were derived, we conclude that the microinjected membrane fragments act as templates for their own three-dimensional organization.

Changes in GTP-dependent fusion and ras-related proteins in membranes from rat hepatocellular carcinomas.

The fusion capacity of rough endoplasmic reticulum membranes isolated from dissected liver tumor nodules of aflatoxin-treated rats was determined by cell free assay to be greater than that of homologous membranes from control liver. In a first attempt to understand the reason for this difference we compared the content of ras-related proteins in rough microsomal fractions and other cell fractions of both dissected tumor nodules and control liver. Using [alpha-32P]GTP blot overlay and densitometric analysis, homogenate, Golgi and rough endoplasmic reticulum fractions from dissected tumor nodules were observed to contain increased amounts of [alpha-32P]GTP binding to ras-related proteins when compared to homologous control fractions. Western blot analysis indicated that ras content was also increased in the tumor fractions. [alpha-32P]GTP-blot overlay using double-dimensional SDS-polyacrylamide gel electrophoresis confirmed quantitative differences in the amount of [alpha-32P]GTP binding to ras-related proteins between fractions from tumor and control tissues and indicated a surprising number of such proteins in each fraction. The data suggest that the changes in ras-related proteins could, in part, account for the enhanced GTP-dependent fusion capacity observed for the tumor-derived membranes.

Tuberculosis in the intensive care unit: a descriptive analysis in a low-burden country.

BACKGROUND: Although tuberculosis (TB) is not a major public health issue in low-burden countries, severe cases are still a matter of concern. OBJECTIVE: To assess the risk factors for mortality due to TB in a low-burden setting. DESIGN: A retrospective study of 97 patients hospitalised with active TB in the intensive care unit (ICU) of the Bichat-Claude Bernard Hospital, Paris, France, from 2000 to 2009. RESULTS: The mean age was 47.4 ± 14.7 years; 40 patients were human immunodeficiency virus (HIV) infected, with a median CD4 cell count of 74 cells/mm(3). The survival analysis showed that 21 patients died during their time in the ICU. The observed risk factors for ICU mortality were organ failure, high Simplified Acute Physiology Score II (SAPS II) and Sequential Organ Failure Assessment scores, and concomitant non-tuberculous infection. In multivariate analysis, only SAPS II score was significantly associated with mortality. CONCLUSION: Risk factors identified in this study are different from those in high-burden countries, and were not associated with the site of TB disease. There was no difference in TB presentation between HIV-infected and non-HIV-infected patients, and HIV was not a mortality risk factor. Low-burden countries still experience high death rates due to severe TB.

Risk factors for prolonged treatment of lymph node tuberculosis.

Lymph node tuberculosis (LNTB) is the most frequent form of extra-pulmonary tuberculosis (TB). Randomised, controlled trials have convincingly demonstrated that 6 months of chemotherapy is sufficient for most drug-susceptible LNTB. We performed a retrospective, multicentric study from 1997 to 2010 to describe factors associated with prolonged anti-tuberculosis treatment in patients with LNTB. Of 126 patients diagnosed with LNTB, 22 (17.5%) were human immunodeficiency virus (HIV) infected. The median treatment duration was 9 months (interquartile range, 6-12). Treatment was significantly longer in patients with HIV (P < 0.01), additional sites of TB (P < 0.01) or weight loss (P = 0.04). Factors independently associated with excessively lengthy treatment were HIV co-infection and the presence of other TB foci.