Plastic physicians: The surgical salamanders of the COVID-19 pandemic.

At the time of writing, coronavirus disease-2019 (COVID-19) has affected 6.42 million people globally and over 380,000 deaths, with the United Kingdom now having the highest death rate in Europe. The plastic surgery department at Leeds Teaching Hospitals put necessary steps in place to maintain an excellent urgent elective and acute service whilst also managing COVID-positive medical patients in the ward. We describe the structures and pathways implemented together with complex decision-making, which has allowed us to respond early and effectively. We hope these lessons will prove a useful tool as we look to open conversations around the recovery of normal activity.

Extracellular vesicles induce protective immunity against Trichuris muris.

Gastrointestinal nematodes, such as Trichuris trichiura (human whipworm), are a major source of morbidity in humans and their livestock. There is a paucity of commercially available vaccines against these parasites, and vaccine development for T. trichiura has been impeded by a lack of known host protective antigens. Experimental vaccinations with T. muris (murine whipworm) soluble Excretory/Secretory (ES) material have demonstrated that it is possible to induce protective immunity in mice; however, the potential for extracellular vesicles (EVs) as a source of antigenic material has remained relatively unexplored. Here, we demonstrate that EVs isolated from T. muris ES can induce protective immunity in mice when administered as a vaccine without adjuvant and show that the protective properties of these EVs are dependent on intact vesicles. We also identified several proteins within EV preparations that are targeted by the host antibodies following vaccination and subsequent infection with T. muris. Many of these proteins, including VWD and vitellogenin N and DUF1943-domain-containing protein, vacuolar protein sorting-associated protein 52 and TSP-1 domain-containing protein, were detected in both soluble ES and EV samples and have homologues in other parasites of medical and veterinary importance, and as such are possible protective antigens.

A sticky end for gastrointestinal helminths; the role of the mucus barrier.

Gastrointestinal (GI) nematodes are a group of successful multicellular parasites that have evolved to coexist within the intestinal niche of multiple species. It is estimated that over 10% of the world's population are chronically infected by GI nematodes, making this group of parasitic nematodes a major burden to global health. Despite the large number of affected individuals, there are few effective treatments to eradicate these infections. Research into GI nematode infections has primarily focused on defining the immunological and pathological consequences on host protection. One important but neglected aspect of host protection is mucus, and the concept that mucus is just a simple barrier is no longer tenable. In fact, mucus is a highly regulated and dynamic-secreted matrix, underpinned by a physical hydrated network of highly glycosylated mucins, which is increasingly recognized to have a key protective role against GI nematode infections. Unravelling the complex interplay between mucins, the underlying epithelium and immune cells during infection are a major challenge and are required to fully define the protective role of the mucus barrier. This review summarizes the current state of knowledge on mucins and the mucus barrier during GI nematode infections, with particular focus on murine models of infection.

Changes in the mucosal barrier during acute and chronic Trichuris muris infection.

The intestinal mucosal barrier, part of the innate immune defence, is responsive to the external environment and changes in response to infection. There is disparate evidence for the epithelial and goblet cell products within the intrinsic barrier being part of a response to resolve infection. We comprehensively analysed the changes of mucosal glycoconjugates during acute and chronic infection by utilising the Trichuris muris (T. muris) model. Transcription factors, atonal homolog 1 (Math-1) and SAM pointed domain containing ETS transcription factor (Spdef) were activated during acute infection, which promoted stem cell fate towards a secretory cell phenotype. The thickness of the intermediate barrier, the carbohydrate-rich glycocalyx, composed of cell surface mucins increased with exposure to T. muris, with an increase in Muc4, Muc13 and Muc17. Overall, hypersecretion of glycoproteins into the extrinsic barrier (mediated by IL-13) via the gamma amino-butyric acid-α3 receptor (GABA-α3), was observed during acute infection. Furthermore, altered glycosylation was observed during acute and chronic infection; mucins were more highly charged during acute infection than during chronic infection. This study readdresses the changes within the mucosal barrier, in particular in the cell surface and secreted mucins during acute and chronic nematode infection.

Thromboembolic prophylaxis in plastic surgery a 12-year follow up in the UK.

Potentially fatal thromboembolic events prevail post-operatively despite the widespread availability of proven methods of prophylaxis. In 1992 Dujon et al published an article which reviewed thromboembolic prophylaxis methods of Consultant Plastic Surgeons in the UK and Ireland. Our follow up study surveyed all current Consultant B.A.P.S members using a modified postal questionnaire to assess practice nationwide. Our conclusions were drawn from comparisons made between the two populations some twelve years apart. Our results show a dramatic change from the previous findings. Since 1992 86% of respondents have developed a set prophylaxis protocol (compared to 19%). The use of low molecular weight heparin has drastically increased by 24% to 76%, the use of flow-tron boots (or similar) has increased by 22% to 68%, the use of TED stockings has increased by 12% to 83%, the use of multi-modality prophylaxis has increased by 27% to 79% Our results demonstrate a definite shift towards multi-modal thromboembolic prophylaxis, possibly due to increased awareness of available technologies and subsequent reduction in costs.

Re-evaluating selection criteria for local anaesthesia in day surgery.

Day surgery is an increasing element of surgical practice, particularly in plastic surgery. A large proportion of work is undertaken using local anaesthesia in the elderly who have associated co-morbidity. At present no national guidelines exist for the use of local anaesthesia in day surgery. This study aimed to examine the relationship between patient selection and complications, in order to identify those who should be excluded from local anaesthetic day surgery treatment. A retrospective analysis of patients undergoing local anaesthetic plastic surgical procedures over a 10-month period identified 328 operative episodes. There were 37 complications, two of which required admission 5 days post surgery for treatment of wound infection. The remaining complications were treated on an outpatient basis. An increased level of complication was seen in males with elevated systolic blood pressure and with the use of full thickness skin grafts in reconstruction. Age, smoking, ASA grade, and medication that altered coagulation (aspirin, warfarin and steroids) were not associated with increased complication levels. We conclude that local anaesthetic plastic surgical procedures are associated with a very low level of risk, and are suitable for those patients traditionally regarded as unsuitable for general anaesthetic day surgery.

Patients awaiting laparoscopic cholecystectomy--can preoperative complications be predicted?

AIMS: To determine the nature and incidence of gallstone-related complications arising in patients awaiting laparoscopic cholecystectomy and to formulate a strategy to detect those most in need of urgent intervention. PATIENTS AND METHODS: A retrospective analysis of the case notes of 337 consecutive patients undergoing laparoscopic cholecystectomy under a single surgeon in a district general hospital between 1995 and 1999. RESULTS: Of patients awaiting laparoscopic cholecystectomy, 65 (19.3%) were documented as suffering significant on-going symptoms, of whom 19 (5.6%) required hospital admission or urgent surgical review at median 8.9 weeks (range 0.1-32.3 weeks) after being placed on the waiting list. Factors predictive of symptom recurrence included: (i) initial acute presentation; (ii) diagnoses of jaundice, pancreatitis, or acute cholecystitis; (iii) elevation of amylase or liver function tests; and (iv) small stones on ultrasonography examination. CONCLUSIONS: A significant proportion of patients awaiting laparoscopic cholecystectomy experience stone-related complications requiring hospital admission. We feel it is possible to reduce this number by selecting those most at risk on the basis of their history and pre-operative investigations for more urgent intervention.

Interaction between mycobacteria and mucus on a human respiratory tissue organ culture model with an air interface.

Mycobacteria adhere specifically to extracellular matrix (ECM) and mucus with a fibrous, but not globular, appearance, in organ cultures of human respiratory mucosa examined by scanning electron microscopy. Previously, light microscopy sections made of tissue infected for 7 days demonstrated mycobacteria associated with mucus on the organ culture surface, and within submucosal glands in areas of damaged epithelium. The authors have now investigated the interactions between Mycobacterium avium complex (MAC), Mycobacterium tuberculosis (MTB), and Mycobacterium smegmatis (MS) and mucus by preincubating bacteria with purified mucins MUC5AC and MUC5B prior to inoculation onto the organ culture mucosal surface. They have also measured mucin production by the organ culture after mycobacterial infection. Mucus did not cause clumping of mycobacteria. There was a significant (P=.03) increase in the amount of fibrous mucus, but not globular mucus, observed on tissue inoculated with mucins compared to controls. The number of bacteria adhering to ECM was markedly reduced after incubation with mucins, which could indicate a protective effect. Mycobacterial infection did not increase mucin production by the organ culture. Mycobacterial adherence to mucins may play a role in the pathogenicity of mycobacteria in diseases such as cystic fibrosis, bronchiectasis, and chronic obstructive pulmonary disease (COPD), in which there are changes in mucus composition and clearance.

The impact of violent injuries on an NHS plastic surgery unit.

BACKGROUND: Violence and injuries caused by violence appear to be increasing. PATIENTS AND METHODS: A prospective study of violent injuries treated in our unit. RESULTS: Over a 5-month period, 148 (21%) of 704 acute admission patients aged 14 years or more and 11 children had injuries due to violence. The head, neck and hands were the commonest sites of injury. Of the 148 patients, 144 (91%) underwent surgery for their injuries. CONCLUSIONS: Injuries due to violence have a significant effect on the resources of our NHS hospital and probably of all NHS hospitals with acute surgical services.

Laparoscopic cholecystectomy without routine operative cholangiography does not result in significant problems related to retained stones.

BACKGROUND: This study investigated whether failure to identify common bile duct stones at laparoscopic cholecystectomy results in significant postoperative complications related to retained stones. METHODS: We performed a retrospective analysis of the case notes of 377 consecutive patients undergoing laparoscopic cholecystectomy without routine operative cholangiography under a single surgeon in a district general hospital between 1995 and 1999. Highly selective preoperative endoscopic retrograde cholangiopancreatography (ERCP) was employed to identify and manage suspected bile duct stones in pancreatitis, jaundice, persistently elevated liver function tests, or a dilated common bile duct. RESULTS: Eighteen (4.8%) of 377 patients presented postoperatively with symptoms/signs suggesting biliary pathology. Two (0.5%) were confirmed to have retained duct stones/debris (ultrasound/ERCP); both recovered with conservative treatment. Only 1 patient of 274 (0.4%) without preoperative ERCP subsequently presented with a symptomatic retained stone, the other having been stented preoperatively. CONCLUSIONS: Highly selective preoperative ERCP without routine operative cholangiography is not associated with a significant increase in morbidity/mortality related to retained stones following laparoscopic cholecystectomy.

Identification of a nonmucin glycoprotein (gp-340) from a purified respiratory mucin preparation: evidence for an association involving the MUC5B mucin.

Rate-zonal centrifugation of a reduced and alkylated respiratory mucin preparation identified a protein-rich fraction. This was subjected to trypsin treatment and one of the many liberated peptides was purified and its N-terminal sequence determined. The peptide was identical to a 14 amino acid sequence from the scavenger receptor cysteine-rich domain containing glycoprotein gp-340. A polyclonal antiserum, raised against the peptide, stained the serous cells in the submucosal glands of human tracheal tissue. The glycoprotein was purified from respiratory mucus by density-gradient centrifugation, gel chromatography, and anion exchange chromatography. The molecule exhibited a heterogeneous distribution of buoyant density (1.28-1.46 g/ml) that overlapped with the gel-forming mucins, was included on Sepharose CL-2B and was quite highly anionic. SDS-PAGE indicated a mass greater than 208 kDa and measurements performed across the molecular size distribution indicated an average M(r) of 5 x 10(5) with a range of M(r) from 2 x 10(5) to 1 x 10(6). Gel chromatography of respiratory mucus extracts ("associative" and "dissociative") indicated that this glycoprotein forms complexes that may involve the large gel-forming mucins MUC5AC and MUC5B. Rate zonal centrifugation suggested such complexes are more likely to involve MUC5B rather than MUC5AC mucins.

Characterization of mucins from cultured normal human tracheobronchial epithelial cells.

Early-passage normal human tracheobronchial epithelial (NHTBE) cells grown in air-liquid interface cultures in medium containing retinoids differentiate into a mucociliary epithelium over a 2- to 3-wk period and express increasing mRNA levels of the airway mucin genes MUC5AC and MUC5B as the cultures age; the levels of MUC2 mRNA were very low throughout the study. Using specific antibodies to MUC5AC and MUC5B mucins, we noted a gradual increase in these two mucins in the intracellular and apically secreted pools as a function of time. A low level of MUC2 mucin was detected, which did not change with time. The intracellular and apically secreted mucins isolated from day 14 and day 21 cultures by density gradient centrifugation were similar in density to those previously isolated from human respiratory mucus secretions. The sedimentation rate of the apically secreted mucins indicated that they were highly oligomerized, polydisperse macromolecules similar to those previously documented from in vivo secretions. In contrast, the cell-associated mucins from the cultured NHTBE cells were much smaller, possibly only monomers and dimers. Anion-exchange chromatography detected no differences in charge density between the reduced and carboxymethylated cell-associated and secreted forms of the MUC5AC and MUC5B mucins. The MUC5AC mucin was of similar charge density to its in vivo counterpart; however, MUC5B was more homogeneous than that found in vivo. Finally, evidence is presented for an intracellular NH(2)-terminal cleavage of the MUC5B mucins. These studies indicate that the mucins produced by cultured NHTBE cells are similar to those found in human airways, suggesting that this cell culture model is suited for studies of respiratory mucin biosynthesis, processing, and assembly.

Physical characterization of the MUC5AC mucin: a highly oligomeric glycoprotein whether isolated from cell culture or in vivo from respiratory mucous secretions.

We have isolated the high-M(r) mucins from growth medium of the early stage of an HT-29 cell culture by gel chromatography and isopycnic density gradient centrifugation. The mucins (buoyant density 1.34-1.44 g/ml) were reactive with an anti-peptide antiserum (MAN-5ACI) raised against a sequence from within the MUC5AC mucin. Similar antisera raised against the MUC2 and MUC5B mucins were not reactive. The MUC5AC reduced-mucin subunits exhibited a homogeneous charge distribution on anion-exchange chromatography, but appeared as two bands, one major and one more minor, after agarose gel electrophoresis. The unreduced mucins had an average M(r) in excess of 40 MDa and were visualized in the electron microscope as large, fine filamentous threads (many microns in length) that after reduction were greatly reduced in size (number average length 570 nm). Agarose gel electrophoresis of unreduced MUC5AC mucins identified a major band just entering the gel with evidence of a 'ladder' of faster-migrating minor bands. Partial reduction of the mucins increased the proportion of the faster bands and at least 16 could be discriminated. M(r) measurements showed that these bands differed by single monomer units. The mucins behaved as very stiff extended structures in solution and this characteristic might explain the poor separation of different-sized oligomers in sedimentation-rate experiments. The cell-culture mucin preparation had similar characteristics of charge and buoyant density to MUC5AC mucins from respiratory secretions in vivo. In addition the MUC5AC mucin from respiratory tract secretions exhibited similar behaviour, reduced and unreduced on agarose gel electrophoresis, indicating that the mucin has a similar molecular phenotype in vivo and in vitro.

Identification in vitreous and molecular cloning of opticin, a novel member of the family of leucine-rich repeat proteins of the extracellular matrix.

A prominent 45-kDa component was identified by protein staining following SDS-polyacrylamide gel electrophoresis of a 4 M guanidine hydrochloride extract from bovine vitreous collagen fibrils. Peptide sequences obtained from this component were used as a basis for the cloning (from human retinal cDNA) and sequencing of a novel member of the leucine-rich repeat extracellular matrix protein family that we have named opticin. Opticin mRNA was found by reverse transcription polymerase chain reaction in ligament and skin as well as in retina. An open reading frame containing 332 amino acids was identified, the first 19 amino acids representing a signal peptide. The deduced amino acid sequence of the mature protein encodes a 35-kDa protein with a calculated isoelectric point of 5.4. The central domain of this protein consists of six B-type leucine-rich repeats. This domain is flanked by cysteine clusters including a C-terminal two-cysteine cluster containing an additional leucine-rich repeat. The N-terminal region contains a cluster of potential O-glycosylation sites, and analysis of bovine vitreous opticin demonstrated the presence of sialylated O-linked oligosaccharides substituting the core protein. Opticin shows highest protein sequence identity to epiphycan (42%) and osteoglycin (35%) and belongs to Class III of the leucine-rich repeat extracellular matrix protein family.