A rapid recovery protocol for head and neck oncology patients undergoing resection, free flap reconstruction, and tracheostomy: a feasibility study.

Enhanced recovery after surgery (ERAS) for head and neck oncology patients was first introduced in 2017 and was found to improve patient outcomes, in line with results from other surgical specialties. This article presents a rapid recovery protocol (RRP) to further enhance perioperative care in conjunction with the ERAS protocol, for patients undergoing ablative surgery together with free flap reconstruction and tracheostomy. A prospective multidisciplinary approach was adopted to identify a specific cohort of patients who would benefit from the RRP. Of 26 patients who fulfilled the eligibility criteria, 16 completed the RRP. On average, these patients spent 5 days less with a tracheostomy and were discharged 7 days sooner when compared to a matched control group of nine patients on the standard postoperative care pathway. This resulted in an approximate monetary saving of £ 9955 per patient for the hospital trust. These results demonstrate that the feasibility study should be rolled out further, as the RRP not only decreased the length of stay but also provided substantial monetary savings without compromising patient outcomes.

Acquisition of microvascular suturing techniques is feasible using objective measures of performance outside of the operating room.

The aim of this study was to determine the effectiveness of a microsurgical simulation course on a group of novice surgeons. The study also aimed to see whether a device to measure manual dexterity (Imperial College Surgical Assessment Device, ICSAD), a global rating scale and an end product assessment tool could be used to objectively measure performance. Thirty surgeons were recruited to take part and were evenly split into novice, intermediate, and expert groups. The novice group took part in a one-week microsurgical course. The assessment of performance was done with the surgeon anastomosing a harvested rat aorta. They were assessed using ICSAD, which records number of hand movements, distance moved by hands and time. The assessment was also video recorded and later watched by two assessors. The procedure performance was scored using a global rating scale and the final anastomosis was scored using an end product assessment tool. The novice surgeons took the assessment at the beginning and at the end of the course. The intermediate and expert group performed the assessment once to use as a comparison to the novice group. By the end of the course the novices performed significantly better in all parameters in comparison to their pre course assessment. The novice group performed similarly to the expert group in their end of course assessment in four out of the five assessment parameters. Simulation using objective measures of performance can be used to effectively to train a group of novice microsurgeons.

Is there any benefit in surgery for potentially malignant disorders of the oral cavity?

Oral epithelial dysplasia grading is currently recognised as the most useful prognostic indicator for predicting conversion of potentially malignant disorders of the oral cavity to squamous cell carcinoma. It is also used as a basis for deciding management options. However, the diagnosis of oral epithelial dysplasia is subjective and thus unreliable. Surgery is currently recommended for removal of high-risk lesions; however, the evidence for its success is lacking, and in some cases, there have been reports of increased recurrence of malignancy following surgical excision. Molecular and genetic markers have been identified and show promising results in identifying which potential malignant disorders are at risk of malignant transformation. The current evidence available for prognosis of potential malignant disorders and its treatment is based on observational and retrospective data. No randomised control trials have been conducted to date to assess the efficacy of surgery in oral epithelial dysplasia. Until good quality evidence is available from well-designed randomised control trials, experts still recommend the surgical removal of potential malignant disorders which are regarded as high risk.

Is there a therapeutic role for cranioplasty?

Cranioplasty is often undertaken as a joint neurosurgical and maxillofacial procedure. The principal aims remain to improve cosmesis and to protect the underlying brain. We report two cases of cranioplasty with subsequent improvement in neurological function and discuss the possible therapeutic role of cranioplasty.

Cutaneous sinuses of dental origin.

We report a case of a cutaneous sinus related to a non-vital lower premolar. The case was misdiagnosed by non-dentally trained medical staff and subsequent treatment proved ineffective. Following referral to an Oral and Maxillofacial clinic the correct cause was established. Correct treatment was followed by rapid resolution of signs and symptoms. This case highlights the need for healthcare professionals dealing with such patients to be aware of the dentition as a cause for cutaneous sinuses in the head and neck region. Those professionals not dentally qualified should enquire about dental pain and consider referral to the dental practitioner or a specialist department for further evaluation. Even those with a dental background can be fooled and a through history and examination is paramount, supplemented by special investigations were appropriate.

Use of omental pedicles in mycotic abdominal aortic aneurysm repair.

We report a case of a sixty year old man with a mycotic infra-renal abdominal aortic aneurysm complicated by a left psoas abscess. After treatment with parenteral antibiotics he underwent early aortic reconstruction with an in-situ prosthetic graft wrapped in an omental pedicle. Mycotic abdominal aortic aneurysms can be treated in this way despite the potential for graft infection from persisting retroperitoneal sepsis.

Torsion of the gallbladder.

The authors report a case of a 79-year-old female who presented with signs and symptoms of acute cholecystitis. She was taken to theatre within 24 h of acute admission to undergo laparoscopic cholecystectomy. The gallbladder was found to have undergone torsion upon its mesentery leading to its infarction and necrosis. Laparoscopic cholecystectomy was performed, and the patient made an uneventful recovery.

Unusual features of the Drosophila melanogaster telomere transposable element HeT-A are conserved in Drosophila yakuba telomere elements.

HeT-A was the first transposable element shown to have a bona fide role in chromosome structure, maintenance of telomeres in Drosophila melanogaster. HeT-A has hallmarks of non-long-terminal-repeat (non-LTR) retrotransposable elements but also has several unique features. We have now isolated HeT-A elements from Drosophila yakuba, showing that the retrotransposon mechanism of telomere maintenance predates the separation of D. melanogaster and D. yakuba (5-15 million years ago). HeT-A elements from the two species show significant sequence divergence, yet unusual features seen in HeT-Amel are conserved in HeT-Ayak. In both species, HeT-A elements are found in head-to-tail tandem arrays in telomeric heterochromatin. In both species, nearly half of the HeT-A sequence is noncoding and shows a distinctive imperfect repeat pattern of A-rich segments. Neither element encodes reverse transcriptase. The HeT-Amel promoter appears to be intermediate between the promoters of non-LTR and of LTR retrotransposons. The HeT-Ayak promoter shows similar features. HeT-Amel has a frameshift within the coding region. HeT-Ayak does not require a frameshift but shows conservation of the polypeptide sequence of the frameshifted product of D. melanogaster.

Substitution of serine or threonine at position 473 of tissue-type plasminogen activator increases its stability in plasma.

Inactivation by slow acting inhibitors in plasma is of little consequence for thrombolysis with wild type t-PA, since it is rapidly cleared from the blood stream and constantly replenished through infusion. However, it becomes increasingly important as the clearance rate of t-PA is reduced, through mutagenesis, to enable the molecule to be long acting and administered by a single bolus injection. The substitution of serine for alanine at position 473 substantially reduced the slow inactivation that occurs at pharmacological levels of t-PA in plasma. Approximately 70% of the activity of A473S remained after 4 h incubation in human plasma compared to approximately 25% for wild type t-PA. Wild type t-PA and A473S showed the same stability in alpha-2-antiplasmin depleted plasma, indicating that the resistance of A473S to inactivation is a result of reduced reactivity towards alpha-2-antiplasmin, the primary slow acting inhibitor of t-PA. The second order rate constant for the inactivation of A473S by purified alpha-2-antiplasmin was approximately 4 fold less than that of wild type t-PA, which is consistent with the results obtained in plasma. Substitution of threonine at position 473 also produced inhibitor resistance, but glycine did not. The substitution of charged or bulky residues at position 473 destroyed enzymatic activity. The mechanism of inhibitor resistance for A473S and A473T appears to be a reduced reactivity towards substrates with arginine at the P1 position. The A473S mutation adds well to T103N, a mutation that causes an approximate 9 fold reduction in the clearance rate of t-PA. The double mutation variant, T103N, A473S had normal plasma clot lysis activity, and was stable in plasma over a 4 h incubation period at 37 degrees C in vitro.

Regeneration of catalytic activity of glutamine synthetase mutants by chemical activation: exploration of the role of arginines 339 and 359 in activity.

In order to understand the nature of ATP and L-glutamate binding to glutamine synthetase, and the involvement of Arg 339 and Arg 359 in catalysis, these amino acids were changed to cysteine via site-directed mutagenesis. Individual mutations (Arg-->Cys) at positions 339 and 359 led to a sharp drop in catalytic activity. Additionally, the Km values for the substrates ATP and glutamate were elevated substantially above the values for wild-type (WT) enzyme. Each cysteine was in turn chemically modified to an arginine "analog" to attempt to "rescue" catalytic activity by covalent modification; 2-chloroacetamidine (CA) (producing a thioether) and 2,2'-dithiobis (acetamidine)(DTBA) (producing a disulfide) were the reagents used to effect these chemical transformations. Upon reaction with CA, both R339C and R359C mutants showed a significant regain of catalytic activity (50% and 70% of WT, respectively) and a drop in Km value for ATP close to that for WT enzyme. With DTBA, chemically modified R339C had a greater kcat than WT glutamine synthetase, but chemically modified R359C only regained a small amount of activity. Modification with DTBA was quantitative for each mutant and each modified enzyme had similar Km values for both ATP and glutamate. The high catalytic activity of DTBA-modified R339C could be reversed to that of unmodified R339C by treatment with dithiothreitol, as expected for a modified enzyme containing a disulfide bond. Modification of each cysteine-containing mutant to a lysine "analog" was accomplished using 3-bromopropylamine (BPA).(ABSTRACT TRUNCATED AT 250 WORDS)

Kinetic and mutagenic studies of the role of the active site residues Asp-50 and Glu-327 of Escherichia coli glutamine synthetase.

The role of Asp-50 and Glu-327 of Escherichia coli glutamine synthetase in catalysis and substrate binding has been interrogated by construction of site-directed mutants at these positions. Steady-state and rapid-quench kinetic methods were used to elucidate contributions of Asp-50 and Glu-327 to the Km values of all three substrates, ATP, glutamate, and NH4+, as well as to the enzymatic kcat value. Kinetic constants were obtained for the D50A enzyme using both Mg2+ and Mn2+ as activating metal ions; the data reveal that Asp-50 has a significant role in both substrate binding and catalysis as reflected by the increases in the Km values for NH4+ and the destabilization of both the ground state and the transition state for phosphoryl transfer. The D50E mutant was found to have activity with Mn2+ but very low activity with Mg2+, the physiologically important metal ion. The kcat/Km values for all three substrates were substantially altered by changing Asp to Glu. The steady-state results for the E327A mutant indicate a decreased kcat/Km value for NH4+ compared to that of the wild-type enzyme. The E327A-Mg2+ enzyme destabilizes the ground state of the ternary complex (E-ATP-Glu-NH4+) and the transition state for phosphoryl transfer while the E327A-Mn2(+)-enzyme provides greater stabilization for the ATP and glutamate complexes but destabilizes phosphoryl transfer steps in the ternary complex. Overall, these results suggest that Asp-50 is likely involved in binding NH4+ and may also play a role in catalyzing deprotonation of NH4+ to form NH3.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of ELISA with activity and ligand-binding methods for the determination of thymidylate synthase concentration.

The determination of enzyme levels in cellular extracts by active site titrations or by catalytic activity measurements is relevant in both science and medicine. However, these techniques assume that enzymes exhibit the same response in crude sample matrices as they do in the purified state. We report here an example of how an enzyme-linked immunosorbent assay (ELISA) was used to determine the true enzyme concentration which was compared to the effective enzyme concentration obtained by ligand binding and catalytic assay methods in a crude bacterial cell extract. Rabbit antibodies specific for Lactobacillus casei thymidylate synthase (TS) were used to develop a highly specific and sensitive heterogeneous noncompetitive ELISA assay with a typical detection limit of 1.4 fmol of TS (100 pg) and a dynamic working range of 3 orders of magnitude. The antibodies showed identical responses for TS, its inhibitory binary complex with 5-fluoro-2'-deoxyuridylate, and its inhibitory ternary complex with 5-fluoro-2'-deoxyuridylate and 5,10-methylenetetrahydrofolate in the immunoassay. L. casei cell-free extracts were subjected to extraction with CM-Sephadex and the various fractions were analyzed by ELISA, active-site titrations, and catalytic assays which demonstrated that assays which assumed full catalytic or ligand-binding competence underestimated the true enzyme level.