[Pharmacokinetic modifications and pharmacokinetic/pharmacodynamic optimization of beta-lactams in ICU]. / Modifications pharmacocinétiques et optimisation pharmacocinétique/pharmacodynamique des bêta-lactamines en réanimation.

Pharmacokinetic modifications in critically ill patients and those induced by ICU therapeutics raise a lot of issues about antibiotic dose adaptation. Beta-lactams are anti-infectious widely used in ICU. Frequent beta-lactam underdoses induce a risk of therapeutic failure potentially lethal and of emergence of bacterial resistance. Overdoses expose to a neurotoxic and nephrotoxic risk. Therefore, an understanding of pharmacokinetics modifications appears to be essential. A global pharmacokinetic/pharmacodynamic approach is required, including use of prolonged or continued beta-lactam infusions to optimise probability of pharmacokinetic/pharmacodynamic target attainment. Beta-lactam therapeutic drug monitoring should also be considered. Experts agree to target a free plasma betalactam concentration above four times the MIC of the causative bacteria for 100 % of the dosing interval. Bayesian methods could permit individualized doses adaptations.

Meningoradiculitis due to varicella zoster virus reactivation in a patient treated with ixekizumab.

INTRODUCTION: Ixekizumab is a recently developed biopharmaceutical used since 2016 in the US and Europe for the treatment of plaque psoriasis. Few adverse effects have been reported in the literature and ixekizumab is not known to increase the risk of viral reactivation. Herein we report the case of an immunocompetent female patient treated with ixekizumab who presented meningoradiculitis due to varicella zoster virus (VZV) reactivation. PATIENTS AND METHODS: A 51-year-old woman, treated with ixekizumab for psoriasis, consulted in March 2018 for left hemicrania headache associated with left facial paralysis, but without fever. Brain MRI scans revealed cerebral venous thrombosis of the superior sagittal sinus. Analysis of cerebrospinal fluid (CSF) revealed lymphocytic meningitis and positive VZV-PCR. PCR blood assay for VZV was negative. Blood concentrations of anti-VZV IgG antibody increased while Anti-VZV IgM antibodies remained negative. The final diagnosis was VZV meningoradiculitis complicated by cerebral thrombophlebitis. The absence of skin rash, the rapid increase in anti-VZV IgG antibodies, the absence of anti-VZV IgM antibodies, and the negative blood PCR assay suggested viral reactivation rather than primary infection. The patient received acyclovir and coumadin and her condition improved rapidly. After multidisciplinary discussion, ixekizumab was reintroduced together with valacyclovir prophylaxis. CONCLUSION: This case raises the question of the risk of viral reactivation during treatment with an IL-17 inhibitor and with biologics in general. Neurological and vascular complications of VZV may occur without skin lesions and their occurrence during ixekizumab therapy must be investigated by PCR testing of CSF for VZV DNA.

The E3 ubiquitin ligase NEDD4 induces endocytosis and lysosomal sorting of connexin 43 to promote loss of gap junctions.

Intercellular communication via gap junctions has an important role in controlling cell growth and in maintaining tissue homeostasis. Connexin 43 (Cx43; also known as GJA1) is the most abundantly expressed gap junction channel protein in humans and acts as a tumor suppressor in multiple tissue types. Cx43 is often dysregulated at the post-translational level during cancer development, resulting in loss of gap junctions. However, the molecular basis underlying the aberrant regulation of Cx43 in cancer cells has remained elusive. Here, we demonstrate that the oncogenic E3 ubiquitin ligase NEDD4 regulates the Cx43 protein level in HeLa cells, both under basal conditions and in response to protein kinase C activation. Furthermore, overexpression of NEDD4, but not a catalytically inactive form of NEDD4, was found to result in nearly complete loss of gap junctions and increased lysosomal degradation of Cx43 in both HeLa and C33A cervical carcinoma cells. Collectively, the data provide new insights into the molecular basis underlying the regulation of gap junction size and represent the first evidence that an oncogenic E3 ubiquitin ligase promotes loss of gap junctions and Cx43 degradation in human carcinoma cells.

Mitotic cells form actin-based bridges with adjacent cells to provide intercellular communication during rounding.

In order to achieve accurate chromosome segregation, eukaryotic cells undergo a dramatic change in morphology to obtain a spherical shape during mitosis. Interphase cells communicate directly with each other by exchanging ions and small molecules via gap junctions, which have important roles in controlling cell growth and differentiation. As cells round up during mitosis, the gap junctional communication between mitotic cells and adjacent interphase cells ceases. Whether mitotic cells use alternative mechanisms for mediating direct cell-cell communication during rounding is currently unknown. Here, we have studied the mechanisms involved in the remodeling of gap junctions during mitosis. We further demonstrate that mitotic cells are able to form actin-based plasma membrane bridges with adjacent cells during rounding. These structures, termed "mitotic nanotubes," were found to be involved in mediating the transport of cytoplasm, including Rab11-positive vesicles, between mitotic cells and adjacent cells. Moreover, a subpool of the gap-junction channel protein connexin43 localized in these intercellular bridges during mitosis. Collectively, the data provide new insights into the mechanisms involved in the remodeling of gap junctions during mitosis and identify actin-based plasma membrane bridges as a novel means of communication between mitotic cells and adjacent cells during rounding.

Loss of LKB1 and p53 synergizes to alter fallopian tube epithelial phenotype and high-grade serous tumorigenesis.

Liver kinase B1 (LKB1) is a tumor suppressor ubiquitously expressed serine/threonine protein kinase involved in energy metabolism and cellular polarity. In microarray experiments that compared normal tubal epithelium with high-grade serous carcinoma (HGSC), we observed a decrease in LKB1 mRNA expression in HGSC. In this study, we demonstrate that loss of cytoplasmic and nuclear LKB1 protein expression is frequently observed in tubal cancer precursor lesions as well as in both sporadic and hereditary HGSCs compared with other ovarian cancer histotypes. Bi-allelic genomic loss of LKB1 in HGSC did not account for the majority of cases with a decrease in protein expression. In vitro, shLKB1-fallopian tube epithelial (FTE) cells underwent premature cellular arrest and in ex vivo FTE culture, LKB1 loss and p53 mutant synergized to disrupt apical to basal polarity and decrease the number of ciliated cells. Overexpression of cyclin E1 allowed for bypass of LKB1-induced cellular arrest, and increased both proliferation and anchorage-independent growth of transformed FTE cells. These data suggest that LKB1 loss early in ovarian serous tumorigenesis has an integral role in tumor promotion by disrupting apical to basal polarity in the presence of mutated p53 in fallopian tube cells.

Connexins in colorectal cancer pathogenesis.

The connexins constitute a family of integral membrane proteins that form channels between adjacent cells. These channels are assembled in plasma membrane domains known as gap junctions and enable cells to directly exchange ions and small molecules. Intercellular communication via gap junctions plays important roles in regulating cell growth and differentiation and in maintaining tissue homeostasis. This type of cell communication is often impaired during cancer development, and several members of the connexin protein family have been shown to act as tumor suppressors. Emerging evidence suggests that the connexin protein family has important roles in colorectal cancer development. In the normal colonic epithelial tissue, three connexin isoforms, connexin 26 (Cx26), Cx32 and Cx43, have been shown to be expressed at the protein level. Colorectal cancer development is associated with loss of connexin expression or relocalization of connexins from the plasma membrane to intracellular compartments. Downregulation of connexins in colorectal carcinomas at the transcriptional level involves cancer-specific promoter hypermethylation. Recent studies suggest that Cx43 may constrain growth of colon cancer cells by interfering with the Wnt/ß-catenin pathway. There is also increasing evidence that the connexins may have potential as prognostic markers in colorectal cancer. This review discusses the role of connexins in colorectal cancer pathogenesis, as well as their potential as prognostic markers and targets in the prevention and treatment of the disease.

NEDD4 is overexpressed in colorectal cancer and promotes colonic cell growth independently of the PI3K/PTEN/AKT pathway.

Ubiquitination controls multiple cellular processes relevant to cancer pathogenesis. Using Gene Set Enrichment Analysis of an mRNA transcriptome dataset, we have identified genes encoding components of the ubiquitin system that are differentially expressed in colorectal cancers as compared to normal colonic mucosa. Among the significantly overexpressed genes was NEDD4 (neural precursor cell-expressed developmentally down-regulated 4), the prototype member of the HECT (homologous to E6AP C-terminus) E3 ubiquitin ligase family. Previous studies have shown that NEDD4 may act as an oncoprotein by inducing ubiquitination and degradation of the tumor suppressor protein PTEN (phosphatase and tensin homolog). To investigate its functional importance in colorectal cancer, HCT-15 and LoVo colon cancer cells were depleted of NEDD4 by small interfering RNA. The depletion resulted in reduced growth and altered cell morphology in both cell lines. However, NEDD4 depletion did not affect the PTEN protein level or PI3K/AKT signaling pathway activation. Moreover, ectopic expression of NEDD4 did not influence the PTEN subcellular localization or protein level. Collectively, these data demonstrate that NEDD4 is overexpressed in colorectal cancers, and suggest that NEDD4 promotes growth of colon cancer cells independently of PTEN and PI3K/AKT signaling.

The gap junction channel protein connexin 43 is covalently modified and regulated by SUMOylation.

SUMOylation is a posttranslational modification in which a member of the small ubiquitin-like modifier (SUMO) family of proteins is conjugated to lysine residues in specific target proteins. Most known SUMOylation target proteins are located in the nucleus, but there is increasing evidence that SUMO may also be a key determinant of many extranuclear processes. Gap junctions consist of arrays of intercellular channels that provide direct transfer of ions and small molecules between adjacent cells. Gap junction channels are formed by integral membrane proteins called connexins, of which the best-studied isoform is connexin 43 (Cx43). Here we show that Cx43 is posttranslationally modified by SUMOylation. The data suggest that the SUMO system regulates the Cx43 protein level and the level of functional Cx43 gap junctions at the plasma membrane. Cx43 was found to be modified by SUMO-1, -2, and -3. Evidence is provided that the membrane-proximal lysines at positions 144 and 237, located in the Cx43 intracellular loop and C-terminal tail, respectively, act as SUMO conjugation sites. Mutations of lysine 144 or lysine 237 resulted in reduced Cx43 SUMOylation and reduced Cx43 protein and gap junction levels. Altogether, these data identify Cx43 as a SUMOylation target protein and represent the first evidence that gap junctions are regulated by the SUMO system.

Comparison of insulin detemir and insulin glargine on glycemic variability in patients with type 1 and type 2 diabetes.

AIMS: To compare the glycemic variability of insulin detemir and insulin glargine in type 1 and type 2 diabetic patients. METHODS: 15 type 1 and 14 type 2 diabetic patients receiving intensive insulin therapy with insulin glargine were enrolled. Before and after switching insulin glargine to insulin detemir, we assessed fasting glucose variability using the standard deviation (SD) and the coefficient of variance (CV) of self-monitored fasting blood sugar (FBS) levels. RESULTS: The SD and CV values were significantly decreased in type 1 diabetes after switching the therapy, though there was no significant difference in type 2 diabetes. The frequency of hypoglycemia was decreased in type 1 diabetes and there was no change in type 2 diabetes. The changes of the CV value also showed significant positive correlation with fasting serum CPR levels in all patients and total insulin dose in type 1 diabetes. The changes of frequency of hypoglycemia showed significant positive correlation with total and basal insulin dose adjusted for body weight in type 1 diabetes. CONCLUSION: The present study demonstrated lower within-subject variability of insulin detemir compared to insulin glargine, suggesting that the basal insulin replacement with insulin detemir may provide a useful therapeutic strategy for uncontrolled type 1 diabetes with high glucose variability.

[Non-cutaneous manifestations of secondary syphilis]. / Manifestations extra-cutanéomuqueuses de la syphilis secondaire.

BACKGROUND: The usual presentation of secondary syphilis is with cutaneous and mucosal symptoms. However, systematic symptoms can also occur. The purpose of this study was to describe non-mucocutaneous manifestations of secondary syphilis. PATIENTS AND METHODS: Patients from the Infectious Diseases Department of Tourcoing Hospital in whom secondary syphilis was diagnosed between January 2000 and December 2006 were enrolled in this study. Patients with secondary syphilis had the typical cutaneous and mucosal symptoms and a VDRLgreater than or equal to one quarter (or a fourfold increase in the VDRL if previously positive). RESULTS: Seventy-seven patients presenting a total of 80 cases of secondary syphilis were enrolled, 50 of whom were HIV-positive. Of these patients, 21 (26.3 p. 100) had neurological symptoms with three cases (3.8 p. 100) of uveitis, four (5 p. 100) of papillitis, two (2.5 p. 100) of retinitis and one (1.25 p. 100) of otosyphilis. In 14 of these 21 patients (67 p. 100), lumbar puncture was performed, confirming the diagnosis of neurosyphilis in six cases. Three patients (3.8 p. 100) had diarrhoea, four (5 p. 100) had abdominal pain and six (7.5 p. 100) had hepatomegaly. Seven (11.5 p. 100) patients had alanine aminotransferase levels above twice the normal upper limit and two above 10 times the normal upper limit. Three patients had bone pain and in one patient, osteitis was confirmed by technetium and gallium scintigraphy (osteolysis). CONCLUSION: In patients with secondary syphilis, clinicians should search for non-mucocutaneous symptoms. In the presence of these symptoms, appropriate syphilis treatment should be initiated.

Erythromycin ameliorates renal injury via anti-inflammatory effects in experimental diabetic rats.

AIMS/HYPOTHESIS: Recent studies have shown that the inflammatory process is involved in the pathogenesis of diabetic nephropathy. Fourteen-membered ring macrolides, including erythromycin, have anti-inflammatory, as well as antibacterial effects. The aim of this study was to investigate the renoprotective effects of erythromycin in streptozotocin (STZ)-induced diabetic rats. METHODS: STZ-induced diabetic rats were treated orally with erythromycin (5 mg/kg body weight) or vehicle every day for 8 weeks. To evaluate the effect of erythromycin treatment, we measured urinary albumin excretion, and examined the following in the kidney: histological changes, the expression of intercellular adhesion molecule-1 (ICAM-1), macrophage infiltration, and nuclear factor-kappa B (NF-kappaB) activity. RESULTS: Erythromycin significantly reduced urinary albumin excretion without affecting blood glucose levels and blood pressure. Erythromycin also attenuated glomerular hypertrophy, mesangial expansion, macrophage infiltration and ICAM-1 expression in renal tissues. The expression of the gene encoding TGFB1 (also known as TGF-beta1), type IV collagen protein production and NF-kappaB activity in renal tissues were increased in diabetic rats and reduced by erythromycin treatment. CONCLUSIONS/INTERPRETATION: Erythromycin prevented renal injuries without changes of blood glucose levels and blood pressure in experimental diabetic rats. These results suggest that the renoprotective effects of erythromycin are based on its anti-inflammatory effect via suppression of NF-kappaB activation. Modulation of microinflammation with erythromycin may provide a new approach for diabetic nephropathy.

Empirical rules predicting conformation of cyclic tetrapeptides from primary structure.

A useful set of empirical rules is put forward to predict the conformations of cyclic tetrapeptides and cyclic tetradepsipeptides on the basis of primary structure, briefly presented as follows: A conformation allowing an intramolecular hydrogen bond (IMHB) of gamma-turn is preferred, and an ester bond always adopts a trans form. On a right-handed peptide ring, the carbonyl group acylating a D residue is oriented to the upper side of the main ring. The carbonyl group acylating a D proline or an N-methyl-D-amino acid residue is oriented to the lower side of the ring, forming a cis bond. The LDDL configurational sequence adopts a cis-trans-cis-trans backbone with Ci symmetry. A glycine residue behaves as a D residue in an L-peptide. Conformations of cyclotetrapeptides containing two glycine residues at diametric positions or containing an N-methyl-dehydroamino acid residue are predicted by use of appendices of rule 5. Almost all conformations of cyclic tetrapeptides are predicted by these rules. Energetical rationalization of the rules and prediction of possible new conformations are described. Conformations of cyclo(-L-Pro-L-Leu-D-Tyr(Me)-L-Ile-)(1) and cyclo (-L-Pro-D-Leu-D-Tyr(Me)-L-Ile)(2) are compared. Results of n.m.r. experiments showed that compound 1 adopts a unique cis-trans-trans-trans backbone with a gamma-turn IMHB, and 2 has a cis-trans-cis-trans backbone with Ci symmetry. These observations confirmed the rules described above. Peptides 1 and 2 are the first diastereomeric peptides with trans (LD) and cis (DD) secondary amide bonds.