Robotic transanal total mesorectal excision: Is the future now?

Total mesorectal excision (TME) is the standard surgical treatment for the curative radical resection of rectal cancers. Minimally invasive TME has been gaining ground favored by the continuous technological advancements. New procedures, such as transanal TME (TaTME), have been introduced to overcome some technical limitations, especially in low rectal tumors, obese patients, and/or narrow pelvis. The earliest TaTME reports showed promising results when compared with the conventional laparoscopic TME. However, recent publications raised concerns regarding the high rates of anastomotic leaks or local recurrences observed in national series. Robotic TaTME (R-TaTME) has been proposed as a novel technique incorporating the potential benefits of a perineal dissection together with precise control of the distal margins, and also offers all those advantages provided by the robotic technology in terms of improved precision and dexterity. Encouraging short-term results have been reported for R-TaTME, but further studies are needed to assess the real role of the new technique in the long-term oncological or functional outcomes. The present review aims to provide a general overview of R-TaTME by analyzing the body of the available literature, with a special focus on the potential benefits, harms, and future perspectives for this novel approach.     

Periscope Proteins are variable-length regulators of bacterial cell surface interactions

Changes at the cell surface enable bacteria to survive in dynamic environments, such as diverse niches of the human host. Here, we reveal “Periscope Proteins” as a widespread mechanism of bacterial surface alteration mediated through protein length variation. Tandem arrays of highly similar folded domains can form an elongated rod-like structure; thus, variation in the number of domains determines how far an N-terminal host ligand binding domain projects from the cell surface. Supported by newly available long-read genome sequencing data, we propose that this class could contain over 50 distinct proteins, including those implicated in host colonization and biofilm formation by human pathogens. In large multidomain proteins, sequence divergence between adjacent domains appears to reduce interdomain misfolding. Periscope Proteins break this “rule,” suggesting that their length variability plays an important role in regulating bacterial interactions with host surfaces, other bacteria, and the immune system.

Bacteria encounter complex and dynamic environments, including within human hosts, and have thus evolved various mechanisms that enable a rapid response for survival within, and exploitation of, new conditions. In addition to classical control by regulation of gene expression, bacteria exploit mechanisms that give rise to random variation to facilitate adaptation [e.g., phase and antigenic variation (1)]. In Gram-positive and Gram-negative human pathogens, DNA inversions (2, 3), homologous recombination (4), DNA methylation (1), and promoter sequence polymorphisms (5) govern changes in bacterial surface components, including capsular polysaccharide and protein adhesins, which can impact bacterial survival and virulence in the host (1, 6). Many of these mechanisms are very well studied and widespread across bacteria.A less well-studied mechanism is length variation in bacterial surface proteins. Variability in the number of sequence repeats in the Rib domain (7)–containing proteins on the surface of Group B streptococci has been linked to pathogenicity and immune evasion (8). The repetitive regions of the Staphylococcus aureus surface protein G (SasG) (9) and Staphylococcus epidermidis SasG homolog, Aap (10), also demonstrate sequence repeat number variability. In SasG, this variability regulates ligand binding by other bacterial proteins in vitro (11) in a process that has been proposed to enable bacterial dissemination in the host. Variations in repeat number have also been noted in the biofilm forming proteins Esp from Enterococcus faecalis (12) and, more recently, CdrA from Pseudomonas aeruiginosa (13). High DNA sequence identity in the genes that encode these proteins is likely to facilitate intragenic recombination events that would lead to repeat number variation (14) and, in turn, to protein sequence repetition. However, such sequence repetition is usually highly disfavored in large multidomain proteins (15), so its existence in these bacterial surface proteins suggests that protein length variation provides an evolutionary benefit. SasG, Aap, and Rib contain N-terminal host ligand binding domains and C-terminal wall attachment motifs; thus our recent demonstration that the repetitive regions of both SasG (16) and Rib (17) form unusual highly elongated rods suggests that host-colonization domains will be projected differing distances from the bacterial surface.Here, we show that repeat number variation in predicted bacterial surface proteins is more widespread and we characterize a third rod-like repetitive region in the Streptococcus gordonii protein (Sgo_0707) formed by tandem array of Streptococcal High Identity Repeats in Tandem (SHIRT) domains. Thus, we propose a growing class of “Periscope Proteins,” in which long, highly similar DNA repeats facilitate expression of surface protein stalks of variable length. This mechanism could enable changes in response to selection pressures and confer key advantages to the organism that include evasion of the host immune system (8) and regulation of surface interactions (11) involved in biofilm formation and host colonization.     

White blood cell count is associated with carotid and femoral atherosclerosis

ObjectiveRelationship of high sensitivity C-reactive protein (hsCRP) with Metabolic Syndrome (MetS) is well documented in many populations, but comprehensive data is lacking in Indian population. Thus, we set out to investigate the association of hsCRP levels with MetS and its features and the effect of obesity and insulin resistance on this association in urban Indians.MethodsThis is a cross-sectional study that included 9517 subjects comprising 4066 subjects with MetS. MetS was defined according to the modified National Cholesterol Education Program (NCEP) Adult Treatment Panel (ATP III) criteria for Asians.ResultsMedian levels of hsCRP were considerably higher in individuals with MetS with higher levels in women compared to men. Among the features of MetS, waist circumference was most strongly correlated with hsCRP levels (r = 0.28) and contributed maximally (β = 0.025 mg/l ln hsCRP, P = 7.4 × 10^?147). Subjects with high risk hsCRP levels (>3 mg/l) were at high risk of MetS (OR (95% CI) = 1.65(1.41–1.92), P = 1.7 × 10^?10). Risk of MetS increased in a dose dependent manner from low risk to high risk hsCRP category with increase in BMI and HOMA-IR.ConclusionsOur findings suggest that hsCRP predicts the risk of MetS, independent of obesity and insulin resistance, and therefore, can be a valuable tool to aid the identification of individuals at risk of MetS. The study provides a lead for future investigation for effects of hsCRP, obesity, and insulin resistance on MetS in this population.     

Beneficial dose conversion after switching from higher doses of shorter-acting erythropoiesis-stimulating agents to C.E.R.A in CKD patients in clinical practice: MINERVA Study

Purpose

To assess whether the correction dose recommended by the summary of product characteristics was adequate and to confirm the adequacy of the recommended conversion dosing strategies from shorter-acting erythropoiesis-stimulating agents (ESAs) to continuous erythropoietin receptor activator (C.E.R.A) in anaemic chronic kidney disease (CKD) patients in the clinical setting.

Methods

This was a 12-month, multicenter, prospective, observational study in anaemic CKD patients on haemodialysis and not on dialysis receiving C.E.R.A (at least one dose).

Results

A total of 227 patients were included (not on dialysis; n = 142; haemodialysis: n = 85). The present analysis was conducted on ESA-naïve patients (not on dialysis: n = 31) and patients switched from other ESA (not on dialysis: n = 63; haemodialysis: n = 57). Both on and not on dialysis patients switched from other ESA received lower starting C.E.R.A doses than those recommended, and remained stable during the 12-month period. The higher the previous ESA dose was, the more beneficial the C.E.R.A dose conversion factor was. The proportion of patients with stable haemoglobin within the target range (11–13 g/dL) did not vary during the 12-month period both in nondialysis CKD patients and in those undergoing dialysis [baseline: 42 (66.7 %) and 34 (59.6 %); month 6: 21 (55.3 %) and 26 (50.0 %); month 12: 20 (64.5 %) and 25 (69.4 %), respectively]. In naïve patients, the mean weight-adjusted C.E.R.A dose during the study (1.19 ± 0.49 µg/kg/month) was similar to the recommended one. C.E.R.A was well tolerated.

Conclusions

Conversion from shorter-acting ESAs to C.E.R.A doses lower than those recommended can efficiently maintain target haemoglobin levels both in nondialysis and haemodialysis CKD patients, particularly when switching from higher ESA doses. A monthly C.E.R.A dose of 1.2 µg/Kg seems adequate for anaemia correction.     

From the Cover: Proton transfers are key elementary steps in ethylene polymerization on isolated chromium(III) silicates

Mononuclear Cr(III) surface sites were synthesized from grafting [Cr(OSi(O^tBu)₃)₃(tetrahydrofurano)₂] on silica partially dehydroxylated at 700 °C, followed by a thermal treatment under vacuum, and characterized by infrared, ultraviolet-visible, electron paramagnetic resonance (EPR), and X-ray absorption spectroscopy (XAS). These sites are highly active in ethylene polymerization to yield polyethylene with a broad molecular weight distribution, similar to that typically obtained from the Phillips catalyst. CO binding, EPR spectroscopy, and poisoning studies indicate that two different types of Cr(III) sites are present on the surface, one of which is active in polymerization. Density functional theory (DFT) calculations using cluster models show that active sites are tricoordinated Cr(III) centers and that the presence of an additional siloxane bridge coordinated to Cr leads to inactive species. From IR spectroscopy and DFT calculations, these tricoordinated Cr(III) sites initiate and regulate the polymer chain length via unique proton transfer steps in polymerization catalysis.Almost half of the world’s high-density polyethylene is produced by the Phillips catalyst, a silica-supported chromium oxide (CrO_x/SiO₂) (1). This catalyst is prepared by incipient wetness impregnation of a chromium salt on silica, followed by high temperature calcination. Contacting this material with ethylene forms the active reduced species in situ that polymerizes ethylene. The Phillips catalyst is active in the absence of activators that are typically required for polymerization catalysts (2). Despite 50 y of research, the catalytically active site and the initiation mechanism, particularly the formation of the first Cr–C bond, remain controversial. Numerous spectroscopic techniques [infrared (IR), ultraviolet-visible (UV-Vis), electron paramagnetic resonance (EPR), X-ray absorption spectroscopy (XAS), etc.] established that the Phillips catalyst contains a complex mixture of surface Cr species, of which only ∼10% are active in polymerization (3, 4). The low number of active sites is one of the main limiting factors in using spectroscopic methods to study this material because the spectroscopic signature mainly belongs to inactive species.Previous molecular approaches to determine the Phillips catalyst ethylene polymerization mechanism focused on systems containing preformed Cr–C bonds (5–7). We recently reported the preparation of well-defined silica-supported Cr(II) and Cr(III) dinuclear sites (8), where Cr(III) species are active polymerization sites, in contrast to Cr(II), which is consistent with extensive research on homogeneous chromium complexes (9–11). We proposed that these well-defined Cr(III) silicates initiate polymerization by the heterolytic cleavage of a C–H bond of ethylene on a Cr–O bond to form a Cr–vinyl species that is capable of inserting ethylene by a Cossee–Arlman mechanism (8). However, extensive studies on Phillips catalyst invoke mononuclear polymerization sites (12–18). Furthermore, direct evidence of the active site structure and the polymerization mechanism is critically needed. Here we investigate the preparation and the detailed characterization of isolated Cr(III) sites supported on silica, prepared by grafting [Cr^III(OSi(O^tBu)₃)₃(tetrahydrofurano; THF)₂] (19) on dehydroxylated silica and a subsequent thermal treatment under vacuum. These isolated Cr(III) sites are highly active in ethylene polymerization in the absence of coactivator. Computational investigations in combination with IR spectroscopy indicate that polymerization occurs on tricoordinate Cr(III) sites and involves two key proton transfer steps: (i) formation of the first Cr–C bond through the C–H activation of ethylene across a Cr–O bond and (ii) termination by the microreverse of the initiation step while chain growth occurs by classical Cossee–Arlman insertion polymerization (20, 21).     

Gene expression profiles of breast cancer metastasis according to organ site

In advanced breast cancer, biomarker identification and patient selection using a metastatic tumor biopsy is becoming more necessary. However, the biology of metastasis according to the organ site is largely unknown. Here, we evaluated the expression of 771 genes in 184 metastatic samples across 11 organs, including liver, lung, brain, and bone, and made the following observations. First, all PAM50 molecular intrinsic subtypes were represented across organs and within immunohistochemistry‐based groups. Second, HER2‐low disease was identified across all organ sites, including bone, and HER2 expression significantly correlated with ERBB2 expression. Third, the majority of expression variation was explained by intrinsic subtype and not organ of metastasis. Fourth, subtypes and individual subtype‐related genes/signatures were significantly associated with overall survival. Fifth, we identified 74 genes whose expression was organ‐specific and subtype‐independent. Finally, immune profiles were found more expressed in lung compared to brain or liver metastasis. Our results suggest that relevant tumor biology can be captured in metastatic tissues across a variety of organ sites; however, unique biological features according to organ site were also identified and future studies should explore their implications in diagnostic and therapeutic interventions.     

X-inactivation of HSD17B10 revealed by cDNA analysis in two female patients with 17β-hydroxysteroid dehydrogenase 10 deficiency

17β-Hydroxysteroid dehydrogenase 10 (HSD10) is a mitochondrial enzyme involved in the degradation pathway of isoleucine and branched-chain fatty acids. The gene encoding HSD10, HSD17B10, has been reported as one of the few genes that escapes X-inactivation. We previously studied two female patients with HSD10 deficiency, one of them was severely affected and the other presented a mild phenotype. To elucidate as to why these two carriers were so differently affected, cDNA analyses were performed. The HSD17B10 cDNA of eight control cell lines, two hemizygous patients and two carriers was obtained from cultured fibroblasts, amplified by PCR and sequenced by standard methods. All HSD17B10 cDNAs were quantified by real-time PCR. In the fibroblasts of the female patient who presented with the severe phenotype, only the mutant allele was identified in the cDNA sequence, which was further confirmed by relative quantification (RQ) of HSD17B10 cDNA. This is in agreement with an unfavourable X-inactivation. The other female patient, with slight clinical affectation, showed the presence of both mutant and wild-type alleles in the cDNA sequence, which was confirmed by RQ of HSD17B10 cDNA in fibroblasts. This is in line with normal X-inactivation and the expression of both alleles in different cells (functional mosaicism). RQ results of HSD17B10 cDNA did not differ significantly between male and female controls, which indicate that the genetic doses of mRNA of HSD17B10 was the same in both sexes. In conclusion, these results suggest that the HSD17B10 gene does not escape X-inactivation as has been reported previously.     

Olive oil in parenteral nutrition

PURPOSE OF REVIEW: A lipid emulsion for use in parenteral nutrition containing a significant proportion of olive oil in place of soybean oil (ClinOleic; Baxter, Maurepas, France) is now available. The purpose of this review is to provide background information about the rationale for this emulsion, to collate and synthesize the literature about it, and to highlight recent studies in which it has been used. RECENT FINDINGS: ClinOleic offered significant advantage over soybean oil-based emulsions in terms of glucose metabolism in preterm infants. ClinOleic was recently used for the first time in malnourished haemodialysis, trauma and burn patients and was found to be safe and well tolerated. In burn patients ClinOleic was associated with better liver function. SUMMARY: ClinOleic is safe and well tolerated in preterm infants, and in home parenteral nutrition, haemodialysis, trauma and burn patients and may offer advantages with regard to liver function, oxidative stress and immune function. ClinOleic may offer significant advantage over soybean oil-based emulsions in terms of glucose metabolism in preterm infants. More clinical studies of ClinOleic are required and these should include evaluation of oxidative stress markers and immune function as well as of clinical outcomes.