Risk factors for surgical site infection after groin hernia repair: does the mesh or technique matter?

INTRODUCTION

Surgical site infections (SSIs) following groin hernia repair (GHR) are getting rarer in high income countries despite a wider use of meshes. Among the risk factors for SSIs, those related to the mesh and the surgical technique have rarely been described.

METHODS

A registry-based multicenter study using prospectively collected data, including SSIs and their potential risk factors, was conducted in the French Hernia-Club.

RESULTS

Between 2012 and 2019, 21,976 consecutive unselected adult patients aged 64.8  ±  15.4 years old (88.9% male) underwent GHR (83.5% unilateral). Fifty four percent were laparoscopic; 97.6% used mesh. The overall incidence of SSI was 0.26%. The incidence of SSI was respectively, 0.24% and 0.19% (p  =  0.420) in open vs laparoscopic repairs; 0.19% and 0.25% (p  =  0.638) for polyester vs polypropylene mesh; In adjusted multivariate analysis focusing on macroporous meshes (which were the most implanted meshes: 23,148 out of 24,099), there were no differences in terms of SSIs' rates regarding the technique: open versus laparoscopy (p  =  0.762) nor the type of mesh used: polypropylene versus polyester (p  =  0.557).

CONCLUSION

The rate of SSI following GHR was low in this large registry study. Mesh type and surgical technique did not affect SSIs rates. Caution is advised when interpreting these data due to this very low rate of SSI and the potential for a type II error.

The Information System of Experimental Pathology of the German Cancer Research Center

The information system of experimental oncopathology of the German Cancer Research Center is a computerized data processing program for studying the etiology, pathogenesis and therapy of experimental cancer. This program is adapted to correlate stored data with those from the thesaurus of human pathology. The system is developed and administered by the histodiagnostic facility which serves to collect and register standardized, centralized and current data from all sources. These are: individual investigators, animal laboratory, and central histodiagnostic facility. To record uniform data, a standardized protocol is introduced which entails data sets for information about animals, substances under study, experimental design, and necropsy and histological changes. The data entry takes place semi-automatically by using different codes grouped into three files: for substances, for animals, and for pathological changes. The code for pathological findings is based on SNOP. For data processing the system ALIS is employed which permits input, check and update; reorganisation and confirmation; evaluation.

The information system is adapted to the organization and research programs of the German Cancer Research Center. It is a flexible system applicable for different conditions in registering and processing diverse information about animal experiments.

Towards a correlative approach for characterising single virus particles by transmission electron microscopy and nanoscale Raman spectroscopy

The morphology and structure of biological nanoparticles, such as viruses, can be efficiently analysed by transmission electron microscopy (TEM).

Population-based cohort study of variation in the use of emergency cholecystectomy for benign gallbladder diseases

Background

The aims of this prospective population-based cohort study were to identify the patient and hospital characteristics associated with emergency cholecystectomy, and the influences of these in determining variations between hospitals.

Methods

Data were collected for consecutive patients undergoing cholecystectomy in acute UK and Irish hospitals between 1 March and 1 May 2014. Potential explanatory variables influencing the performance of emergency cholecystectomy were analysed by means of multilevel, multivariable logistic regression modelling using a two-level hierarchical structure with patients (level 1) nested within hospitals (level 2).

Results

Data were collected on 4744 cholecystectomies from 165 hospitals. Increasing age, lower ASA fitness grade, biliary colic, the need for further imaging (magnetic retrograde cholangiopancreatography), endoscopic interventions (endoscopic retrograde cholangiopancreatography) and admission to a non-biliary centre significantly reduced the likelihood of an emergency cholecystectomy being performed. The multilevel model was used to calculate the probability of receiving an emergency cholecystectomy for a woman aged 40 years or over with an ASA grade of I or II and a BMI of at least 25·0 kg/m2, who presented with acute cholecystitis with an ultrasound scan showing a thick-walled gallbladder and a normal common bile duct. The mean predicted probability of receiving an emergency cholecystectomy was 0·52 (95 per cent c.i. 0·45 to 0·57). The predicted probabilities ranged from 0·02 to 0·95 across the 165 hospitals, demonstrating significant variation between hospitals.

Conclusion

Patients with similar characteristics presenting to different hospitals with acute gallbladder pathology do not receive comparable care.

Approaches to prepare perfluoroalkyl and pentafluorophenyl copper couples for cross-coupling reactions with organohalogen compounds

The reactions of iodoperfluoroalkanes CnF2n+1I (n = 2, 3, 4) and n-BuLi at low temperatures give NMR spectroscopic evidence for LiCnF2n+1 which were converted into LiCu(CnF2n+1)2 derivatives upon treatment with 0.5 mol copper(i) bromide, CuBr. An alternative route to obtain perfluoroorgano copper couples, Cu(Rf)2Ag (Rf = n-C3F7, n-C4F9, C6F5) was achieved from the reactions of the corresponding perfluoroorgano silver(i) reagents, AgRf, and elemental copper through redox transmetallations. The composition of the resulting reactive intermediates was investigated by means of (19)F NMR spectroscopy and ESI mass spectrometry. Perfluoro-n-propyl and perfluoro-n-butyl copper-silver reagents prepared by the oxidative transmetallation route exhibited good properties in C-C bond formation reactions with acid chlorides even under moderate conditions. Substitution of bromine directly bound to aromatics for perfluoroalkyl groups was achieved at elevated temperatures, while success in halide substitution reactions using lithium copper couples remained poor.

Comparison between the Molecular and Crystal Structures of a Benzylpenicillin Ester and its Corresponding Sulfoxide with Drastically Reduced Biological Activity

A comparative X-ray structure determination was performed to elucidate possible conformational differences between penicillins and penicillin sulfoxides. Penicillin-G-acetoxy-methylester and its β-oxide were used as model substances, because the only chemical difference between both compounds resides in the thiazolidine ring sulfur oxidation. On the basis of the X-ray data as well as of infrared measurements it is discussed that the drastically reduced biological activity of the penicillin-G-sulfoxide might be related to conformational differences in thiazolidine ring puckering or, even more simply, to the geometric position of the sulfoxide oxygen atom, both of which may hamper the proper reaction of the sulfoxide with its target enzyme(s)

Neue Untersuchungen zur Herstellung von Chlornitrat ClONO2 [1] / New Methods for the Preparation of Chlorine Nitrate ClONO2 [1]

ClONO2 can be prepared in good yields from the reactions of anhydrous metal nitrates M(NO3)2 (M = Ca, Sr, Pb) with ClF as well as from the direct reaction of Cl2, HgO and N2O5.

Healthy ageing and home: the perspectives of very old people in five European countries

This paper reports on in-depth research, using a grounded theory approach, to examine the ways in which very old people perceive healthy ageing in the context of living alone at home within urban settings in five European countries. This qualitative study was part of a cross-national project entitled ENABLE-AGE which examined the relationship between home and healthy ageing. Interviews explored the notion of healthy ageing, the meaning and importance of home, conceptualisations of independence and autonomy and links between healthy ageing and home. Data analysis identified five ways in which older people constructed healthy ageing: home and keeping active; managing lifestyles, health and illness; balancing social life; and balancing material and financial circumstances. Older people reflected on their everyday lives at home in terms of being engaged in purposeful, meaningful action and evaluated healthy ageing in relation to the symbolic and practical affordances of the home, contextualised within constructions of their national context. The research suggests that older people perceive healthy ageing as an active achievement, created through individual, personal effort and supported through social ties despite the health, financial and social decline associated with growing older. The physicality and spatiality of home provided the context for establishing and evaluating the notion of healthy ageing, whilst the experienced relationship between home, life history and identity created a meaningful space within which healthy ageing was negotiated.

IR spectroscopic analyses of amyloid fibril formation of β2-microglobulin using a simplified procedure for its in vitro generation at neutral pH

β2-microglobulin (β2m) is known to be the major component of fibrillar deposits in the joints of patients suffering from dialysis-related amyloidosis. We have developed a simplified procedure to convert monomeric recombinant β2m into amyloid fibrils at physiological pH by a combination of stirring and heating, enabling us to follow conformational changes associated with the assembly by infrared spectroscopy and electron microscopy. Our studies reveal that fibrillogenesis begins with the formation of relatively large aggregates, with secondary structure not significantly altered by the stirring-induced association. In contrast, the conversion of the amorphous aggregates into amyloid fibrils is associated with a profound re-organization at the level of the secondary and tertiary structures, leading to non-native like parallel arrangements of the β-strands in the fully formed amyloid structure of β2m. This study highlights the power of an approach to investigate the formation of β2m fibrils by a combination of biophysical techniques including IR spectroscopy.

Ocean enemy's lasting sting: chronic cutaneous reaction after Cnidarian attack

Cnidaria stings cause a wide range of cutaneous and systemic symptoms, normally occurring shortly after the venomous insult (1). We report a case of worsening cutaneous reaction over an eight-year period following a Cnidaria attack sustained whilst maritime swimming. The lesion was characterised by severe, ulcerating chronic inflammation that required wide local excision and skin grafting. Prevention and early identification of Cnidaria envenomation is important for those treating maritime swimmers.

Direct optical detection of viral nucleoprotein binding to an anti-influenza aptamer

We have demonstrated label-free optical detection of viral nucleoprotein binding to a polyvalent anti-influenza aptamer by monitoring the surface-enhanced Raman (SERS) spectra of the aptamer-nucleoprotein complex. The SERS spectra demonstrated that selective binding of the aptamer-nucleoprotein complex could be differentiated from that of the aptamer alone based solely on the direct spectral signature for the aptamer-nucleoprotein complex. Multivariate statistical methods, including principal components analysis, hierarchical clustering, and partial least squares, were used to confirm statistically significant differences between the spectra of the aptamer-nucleoprotein complex and the spectra of the unbound aptamer. Two separate negative controls were used to evaluate the specificity of binding of the viral nucleoproteins to this aptamer. In both cases, no spectral changes were observed that showed protein binding to the control surfaces, indicating a high degree of specificity for the binding of influenza viral nucleoproteins only to the influenza-specific aptamer. Statistical analysis of the spectra supports this interpretation. AFM images demonstrate morphological changes consistent with formation of the influenza aptamer-nucleoprotein complex. These results provide the first evidence for the use of aptamer-modified SERS substrates as diagnostic tools for influenza virus detection in a complex biological matrix.

Detection of viral nucleoprotein binding to anti-influenza aptamers via SERS

A highly sensitive surface-enhanced Raman (SERS)-based method for detection of influenza viral nucleoproteins is described. The intrinsic SERS spectrum of the aptamer-nucleoprotein complex provides direct evidence of binding between a polyvalent anti-influenza aptamer and the nucleoproteins of three influenza strains.

Identification of the protease cleavage sites in a reconstituted Gag polyprotein of an HERV-K(HML-2) element

BACKGROUND

The human genome harbors several largely preserved HERV-K(HML-2) elements. Although this retroviral family comes closest of all known HERVs to producing replication competent virions, mutations acquired during their chromosomal residence have rendered them incapable of expressing infectious particles. This also holds true for the HERV-K113 element that has conserved open reading frames (ORFs) for all its proteins in addition to a functional LTR promoter. Uncertainty concerning the localization and impact of post-insertional mutations has greatly hampered the functional characterization of these ancient retroviruses and their proteins. However, analogous to other betaretroviruses, it is known that HERV-K(HML-2) virions undergo a maturation process during or shortly after release from the host cell. During this process, the subdomains of the Gag polyproteins are released by proteolytic cleavage, although the nature of the mature HERV-K(HML-2) Gag proteins and the exact position of the cleavage sites have until now remained unknown.

RESULTS

By aligning the amino acid sequences encoded by the gag-pro-pol ORFs of HERV-K113 with the corresponding segments from 10 other well-preserved human specific elements we identified non-synonymous post-insertional mutations that have occurred in this region of the provirus. Reversion of these mutations and a partial codon optimization facilitated the large-scale production of maturation-competent HERV-K113 virus-like particles (VLPs). The Gag subdomains of purified mature VLPs were separated by reversed-phase high-pressure liquid chromatography and initially characterized using specific antibodies. Cleavage sites were identified by mass spectrometry and N-terminal sequencing and confirmed by mutagenesis. Our results indicate that the gag gene product Pr74Gag of HERV-K(HML-2) is processed to yield p15-MA (matrix), SP1 (spacer peptide of 14 amino acids), p15, p27-CA (capsid), p10-NC (nucleocapsid) and two C-terminally encoded glutamine- and proline-rich peptides, QP1 and QP2, spanning 23 and 19 amino acids, respectively.

CONCLUSIONS

Expression of reconstituted sequences of original HERV elements is an important tool for studying fundamental aspects of the biology of these ancient viruses. The analysis of HERV-K(HML-2) Gag processing and the nature of the mature Gag proteins presented here will facilitate further studies of the discrete functions of these proteins and of their potential impact on the human host.

Type-IV pili spectroscopic markers: applications in the quantification of piliation levels in Moraxella bovis cells by a FT-IR ANN-based model

Type-IV pili are cell surface organelles found in a wide variety of Gram-negative bacteria. They have traditionally been detected by electron microscopy and ELISA techniques. However, these methodologies are not appropriate for the rapid discrimination and quantification of piliated and nonpiliated cells in industrial or field conditions. Here, the analysis of FT-IR spectra of piliated, nonpiliated and sheared Moraxella bovis cells, together with purified pili suspensions spectra, allowed the identification of 3 IR regions associated to spectroscopic markers of Type-IV pili: 1750-1600, 1450-1350 and 1280-950 cm(-1). Such IR-specific markers were found for piliated cells grown in different culture systems (liquid or solid media), independently of the strain or pili serotype. They were also sensitive to pili expression levels. Therefore, on the bases of these specific spectral features, an FT-IR ANN-based model was developed to classify piliation levels in 5 distinct groups. An overall classification rate of almost 90% demonstrates the strong potential of the ANN system developed to monitor M. bovis cultures in vaccine production.

Rapid identification of Burkholderia cepacia complex species including strains of the novel Taxon K, recovered from cystic fibrosis patients by intact cell MALDI-ToF mass spectrometry

Two approaches based on intact cell matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (IC-MALDI-ToF MS) have been evaluated in order to discriminate and identify nine former Burkholderia cepacia complex (Bcc) species, Burkholderia contaminans belonging to the novel Taxon K, Burkholderia gladioli, and the most relevant non-fermentative (NF) Gram-negative rods recovered from cystic fibrosis (CF) sputum cultures. In total, 146 clinical isolates and 26 reference strains were analysed. IC mass spectra were obtained with high reproducibility applying a recently developed inactivation protocol which is based on the extraction of microbial proteins by trifluoroacetic acid (TFA). In a first approach, spectral analysis was carried out by means of a gel-view representation of mass spectra, which turned out to be useful to recognize specific identifying biomarker proteins (SIBPs). A series of prominent mass peaks, mainly assigned to constitutively expressed proteins, were selected as SIBPs for identifications at the genus and species level. Two distinctive mass peaks present in B. contaminans spectra (7501 and 7900 Da) were proposed as SIBPs for the identification of this novel species. A second approach of spectral analysis based on data reduction, feature selection and subsequent hierarchical cluster analysis was used to obtain an objective discrimination of all species analysed. Both complementary modalities of analyzing complex IC-MALDI-ToF MS data open the path towards a rapid, accurate and objective means of routine clinical microbiology diagnosis of pathogens from sputum samples of CF patients.

Changes in protein structure and distribution observed at pre-clinical stages of scrapie pathogenesis

Scrapie is a neurodegenerative disorder that involves the misfolding, aggregation and accumulation of the prion protein (PrP). The normal cellular PrP (PrP(C)) is rich in alpha-helical secondary structure, whereas the disease-associated pathogenic form of the protein (PrP(Sc)) has an anomalously high beta-sheet content. In this study, protein structural changes were examined in situ in the dorsal root ganglia from perorally 263K scrapie-infected and mock-infected hamsters using synchrotron Fourier Transform InfraRed Microspectroscopy (FTIRM) at four time points over the course of the disease (pre-clinical, 100 and 130 days post-infection (dpi); first clinical signs ( approximately 145 dpi); and terminal ( approximately 170 dpi)). Results showed clear changes in the total protein content, structure, and distribution as the disease progressed. At pre-clinical time points, the scrapie-infected animals exhibited a significant increase in protein expression, but the beta-sheet protein content was significantly lower than controls. Based on these findings, we suggest that the pre-clinical stages of scrapie are characterized by an overexpression of proteins low in beta-sheet content. As the disease progressed, the beta-sheet content increased significantly. Immunostaining with a PrP-specific antibody, 3F4, confirmed that this increase was partly - but not solely - due to the formation of PrP(Sc) in the tissue and indicated that other proteins high in beta-sheet were produced, either by overexpression or misfolding. Elevated beta-sheet was observed near the cell membrane at pre-clinical time points and also in the cytoplasm of infected neurons at later stages of infection. At the terminal stage of the disease, the protein expression declined significantly, likely due to degeneration and death of neurons. These dramatic changes in protein content and structure, especially at pre-clinical time points, emphasize the possibility for identifying other proteins involved in early pathogenesis, which are important for a further understanding of the disease.

Early stages of misfolding and association of beta2-microglobulin: insights from infrared spectroscopy and dynamic light scattering

Conformational changes associated with the assembly of recombinant beta 2-microglobulin in vitro under acidic conditions were investigated using infrared spectroscopy and static and dynamic light scattering. In parallel, the morphology of the different aggregated species obtained under defined conditions was characterized by electron microscopy. The initial salt-induced aggregate form of beta 2-microglobulin, composed of small oligomers (dimers to tetramers), revealed the presence of beta-strands organized in an intramolecular-like fashion. Further particle growth was accompanied by the formation of intermolecular beta-sheet structure and led to short curved forms. An increase in temperature by only 25 degrees C was able to disaggregate these assemblies, followed by the formation of longer filamentous structures. In contrast, a rise in temperature up to 100 degrees C was associated with a reorganization of the short curved forms at the level of secondary structure and the state of assembly, leading to a species with a characteristic infrared spectrum different from those of all the other aggregates observed before, suggesting a unique overall structure. The infrared spectral features of this species were nearly identical to those of beta 2-microglobulin assemblies formed at low ionic strength with agitation, indicating the presence of fibrils, which was confirmed by electron microscopy. The observed spectroscopic changes suggest that the heat-triggered conversion of the short curved assemblies into fibrils involves a reorganization of the beta-strands from an antiparallel arrangement to a parallel arrangement, with the latter being characteristic of amyloid fibrils of beta 2-microglobulin.

Analytical applications of Fourier transform-infrared (FT-IR) spectroscopy in microbiology and prion research

A genuine biophysical method, Fourier transform-infrared (FT-IR) spectroscopy has become a versatile research tool in biochemistry and biomedicine. Topical applications in microbiology and prion research are impressive illustrations of the vigorous evolution of the technique. FT-IR spectroscopy has established itself as a powerful method for the rapid differentiation and identification of microorganisms, thereby contributing to both clinical medicine and the prevention of bioterrorism. It has also led to considerable progress in various other fields of basic research, not least in prion sciences. In this field, FT-IR spectroscopy has been increasingly applied as a tool for elucidating structural features of the pathological prion protein, and also to study the molecular changes induced by prions in neuronal tissue and blood. This article sets out to give a review of current examples of the analytical potential of FT-IR spectroscopy in microbiology and prion research.