Establishment of four head and neck squamous cell carcinoma cell lines: importance of reference DNA for accurate genomic characterisation.

OBJECTIVE: There is significant interest in developing early passage cell lines with matched normal reference DNA to facilitate a precision medicine approach in assessing drug response. This study aimed to establish early passage cell lines, and perform whole exome sequencing and short tandem repeat profiling on matched normal reference DNA, primary tumour and corresponding cell lines. METHODS: A cell culture based, in vitro study was conducted of patients with primary human papillomavirus positive and human papillomavirus negative tumours. RESULTS: Four early passage cell lines were established. Two cell lines were human papillomavirus positive, confirmed by sequencing and p16 immunoblotting. Short tandem repeat profiling confirmed that all cell lines were established from their index tumours. Whole exome sequencing revealed that the matched normal reference DNA was critical for accurate mutational analysis: a high rate of false positive mutation calls were excluded (87.6 per cent). CONCLUSION: Early passage cell lines were successfully established. Patient-matched reference DNA is important for accurate cell line mutational calls.

Anterolateral thigh butterfly free flap for reconstruction of laryngopharyngeal defect: surgical considerations.

BACKGROUND: Reconstruction of a pharyngoesophageal defect remains a challenging problem, especially with involvement of the neck skin. This study aimed to demonstrate the surgical technique of utilising a butterfly modification of the anterolateral thigh flap. RESULTS: Reconstruction of the pharyngoesophageal defect was accomplished using the butterfly modification of the anterolateral thigh free flap. The flap was tubed on the leg while still being attached to the pedicle, to minimise the ischaemia time. CONCLUSION: Butterfly anterolateral thigh free flap allows for multi-layer closure of the neopharynx and can be utilised for reconstruction of pharyngoesophageal and neck skin defects.

Surgical management of advanced pleomorphic dermal sarcoma of the occipital scalp.

Pleomorphic dermal sarcoma is a rare neoplasm of mesenchymal origin that most commonly affects the head. We describe the presentation of a 61-year-old man with a 10-week history of an exophytic lesion affecting the occipital scalp, demonstrating rapid growth. The final histopathology revealed a completely excised 9cm pleomorphic dermal sarcoma (pT2aN0M0, Stage 3), one of the largest such lesions reported in the literature to date. This patient's management involved a wide local subperiosteal excision onto the cranium, with a reconstruction with an Integra dermal regeneration template (Integra LifeSciences, Princeton, NJ, USA) and healing with secondary intention. This was mainly due to poorly defined clinical margins on primary excision, the potential for further excision of involved margins (later confirmed as not needed) and the patient's comorbidities, making a return to theatre for definitive reconstruction undesirable.

Closure of tracheocutaneous fistula using prefabricated conchal bowl cartilage and a supraclavicular flap.

BACKGROUND: Tracheocutaneous fistula represents one of the most troublesome complications of prolonged tracheostomy. Simple closure of a fistula can be ineffective, particularly in the context of prior surgery and adjuvant radiation. As such, modes of repair have expanded to include locoregional flaps and even free tissue transfers. OBJECTIVE: This paper describes a case of persistent tracheocutaneous fistula in an irradiated patient who had undergone previous unsuccessful attempts at repair. METHOD AND RESULTS: The use of regional fasciocutaneous supraclavicular flap with prefabricated conchal bowl cartilage resulted in successful closure of the tracheocutaneous fistula. CONCLUSION: This represents a novel technique for closure of such fistulas in patients for whom previous attempts have failed. This mode of repair should be added to the surgeon's repertoire of reparative techniques.

Sunitinib in metastatic renal cell carcinoma: Experience from single center study, efficacy and safety.

BACKGROUND: The 5-year survival rate for metastatic renal cell carcinoma (RCC) is estimated to be <10%. RCC is highly resistant to chemotherapy. Targeted agents are now first choice of therapy for metastatic RCC such as sunitinib and sorafenib. METHODS: This study is a retrospective analysis of 15 patients having metastatic RCC treated with sunitinib. Apart from three patients, all had clear cell histology. Thirteen patients received dosage of 50 mg/d (4 weeks on/2 weeks off cycles). In 14 patients sunitinib was used as 1st line. The primary end point was objective response rate. Secondary end points were progression free survival (PFS) and safety. RESULTS: Until date of reporting, 3 out of 15 patients are currently on sunitinib. The most common Memorial Sloan = Kettering Cancer Centre poor prognostic factor was an interval of <1 year between diagnosis and starting of treatment (80%). The objective response rate was 13.66% (complete response [CR] + partial response [PR] = 0 + 2). Clinical benefit rate (CR + PR + stable disease) was 60% (n = 9). Median PFS in this study was 7.5 months, with a range of 2-22 month. Median overall survival (OS) of patients in this study was 12 months with a range of 3-24 month. An impact of the dose or/and number of cycles on response was seen in this study, with patients having average cycles >3 showing better response rates, PFS and OS. Major toxicities seen were fatigue ( n= 7), diarrhea (n = 3) and skin rash (n = 4) with majority patients experienced Grade 1-2 toxicities. While Grade 3-4 toxicities include fatigue (n = 1), mucositis (n = 1) and nausea (n = 1). CONCLUSIONS: These results confirm efficacy and safety profile of sunitinib in metastatic RCC, particularly as a first line. Sunitinib produced a 60% disease control rate for metastatic RCC in Indian patients, with acceptable rates of toxicity at a dose of 50 mg daily. Response rates were well matched to other studies confirming the efficacy of sunitinib.

Free hydroxyl radicals are formed on reaction between the neutrophil-derived species superoxide anion and hypochlorous acid.

Superoxide anion reacts with hypochlorous acid to yield free hydroxyl radicals, as shown by the hydroxylation of benzoate. This reaction is analogous to the Haber-Weiss reaction but in the absence of metal ions is at least six orders of magnitude faster.

Oxidative denitrification of the antitumour drug hydroxyguanidine.

The oxidative denitrification of the antitumour agent hydroxyguanidine (HOG) has been investigated by radiolysis methods and EPR spectroscopy. The azide radical (N3.), a model one-electron oxidant, reacts with HOG with the rate constant 5.1 x 10(9) dm3 mol(-1) s(-1) to yield the guanidino carbon-centred radical (HOG.) which rapidly eliminates nitric oxide (k = 3.1 x 10[3] s[-1]) with the concomitant formation of urea. The HOG. undergoes conjugation with molecular oxygen to form a peroxyl radical (HOGOO.) with a rate constant 8.8 x 10(8) dm3 mol(-1) s(-1). The HOGOO. radical also eliminates nitric oxide but may act as a precursor to the peroxynitrite (ONOO-) ion. The oxidation of HOG by the dibromide radical (Br2.-) was found to release nitric oxide with a yield of 95% relative to Br2.- as determined from the combined yields of inorganic nitrite, nitrate and a HOG/nitric oxide-adduct. This study provides a possible mechanistic basis for the oxidative denitrification of HOG which may contribute to the observed toxicity of the drug both in vitro and in vivo and for the oxidation of nonphysiological hydroxyguanidines to NO. via nitric oxide synthase-independent pathways.

Radicals from one-electron reduction of nitro compounds, aromatic N-oxides and quinones: the kinetic basis for hypoxia-selective, bioreductive drugs.

Drugs based on nitroarene, aromatic N-oxide or quinone structures are frequently reduced by cellular reductases to toxic products. Reduction often involves free radicals as intermediates which react rapidly with oxygen to form superoxide radicals, inhibiting drug reduction. The elevation of cellular oxidative stress accompanying oxygen inhibition of reduction is generally less damaging than drug reduction to toxic products, so the drugs offer selective toxicity to hypoxic cells. Since such cells are resistant to radiotherapy, these bioreductive drugs offer potential in tumour therapy. The basis for the selectivity of action entails kinetic competition involving the contesting reaction pathways. The reduction potential of the drug, radical pKa and nature of radical/radical decay kinetics all influence drug activity and selectivity, including the range of oxygen tensions over which the drug offers selective toxicity. These properties may be quantified using generation of radicals by pulse radiolysis, presenting a physicochemical basis for rational drug design.

Reduction of nitroimidazoles in model chemical and biological systems.

Some chemical and biological properties of intermediates obtained during reduction of nitroimidazoles are discussed. These include: rate data for the decay of the nitro radical-anion, stoichiometry and absorption spectra for reduction via the radical-anion or using dithionite, stoichiometry with other reducing agents, and rate of reduction by xanthine/xanthine oxidase. Increased radiosensitization by misonidazole is seen upon prolonged pre-irradiation incubation using E. coli, enabling demonstration that a freely-diffusable metabolite is responsible for this effect. Preliminary experiments designed to extend studies of the radiobiological properties of extracellularly-added metabolites to mammalian cells and the use of liver perfusion to generate metabolites are described.

2-Cyclopropylindoloquinones and their analogues as bioreductively activated antitumor agents: structure-activity in vitro and efficacy in vivo.

A series of 2-cycloalkyl- and 2-alkyl-3-(hydroxymethyl)-1-methylindoloquinones and corresponding carbamates have been synthesized and substituted in the 5-position with a variety of substituted and unsubstituted aziridines. Cytotoxicity against hypoxic cells in vitro was dependent upon the presence of a 5-aziridinyl or a substituted aziridinyl substituent for 3-hydroxymethyl analogues. The activity of 5-methoxy derivatives was dependent upon the presence of a 3-(carbamoyloxy)methyl substituent. Increasing the steric bulk at the 2-position reduced the compounds' effectiveness against hypoxic cells. A 2-cyclopropyl substituent was up to 2 orders of magnitude more effective than a 2-isopropyl substituent, suggesting possible radical ring-opening reactions contributing to toxicity. Nonfused 2-cyclopropylmitosenes were more effective than related fused cyclopropamitosenes reported previously. The reduction potentials of the quinone/semiquinone one-electron couples were in the range -286 to -380 mV. The semiquinone radicals reacted with oxygen with rate constants 2-8 x 10(8) dm3 mol-1 s-1. The involvement of the two-electron reduced hydroquinone in the mediation of cytotoxicity is implicated. The most effective compounds in vitro were the 2-cyclopropyl and 5-(2-methylaziridinyl) derivatives, and of these, 5-(aziridin-1-yl)-2-cyclopropyl-3-(hydroxymethyl)-1-methylindole-4 ,7-dione (21) and 3-(hydroxymethyl)-5-(2-methylaziridin-1-yl)-1,2-dimethylindole+ ++-4,7-dione (54) were evaluated in vivo. Both compounds showed antitumor activity both as single agents and in combination with radiation, with some substantial improvements over EO9 (3) at maximum tolerated doses and as single agents against the RIF-1 tumor model and comparable efficacy in the KHT tumor model.

Indolequinone antitumor agents: reductive activation and elimination from (5-methoxy-1-methyl-4,7-dioxoindol-3-yl)methyl derivatives and hypoxia-selective cytotoxicity in vitro.

A series of indolequinones bearing a variety of leaving groups at the (indol-3-yl)methyl position was synthesized by functionalization of the corresponding 3-(hydroxymethyl)indolequinone, and the resulting compounds were evaluated in vitro as bioreductively activated cytotoxins. The elimination of a range of functional groups-carboxylate, phenol, and thiol-was demonstrated upon reductive activation under both chemical and quantitative radiolytic conditions. Only those compounds which eliminated such groups under both sets of conditions exhibited significant hypoxia selectivity, with anoxic:oxic toxicity ratios in the range 10-200. With the exception of the 3-hydroxymethyl derivative, radiolytic generation of semiquinone radicals and HPLC analysis indicated that efficient elimination of the leaving group occurred following one-electron reduction of the parent compound. The active species in leaving group elimination was predominantly the hydroquinone rather than the semiquinone radical. The resulting iminium derivative acted as an alkylating agent and was efficiently trapped by added thiol following chemical reduction and by either water or 2-propanol following radiolytic reduction. A chain reaction in the radical-initiated reduction of these indolequinones (not seen in a simpler benzoquinone) in the presence of a hydrogen donor (2-propanol) was observed. Compounds that were unsubstituted at C-2 were found to be up to 300 times more potent as cytotoxins than their 2-alkyl-substituted analogues in V79-379A cells, but with lower hypoxic cytotoxicity ratios.

Clinical pharmacokinetics of newer cephalosporins.

Several new cephalosporins have been developed in recent years. These agents include several oral and parenteral agents with extended activity against Gram-negative pathogens. The pharmacokinetic literature for these agents is quite extensive; therefore, we have summarised this information and presented it in tabular form for critical comparison. With a few exceptions, the newer cephalosporins share similar pharmacokinetic properties. Cefixime, cefetamet pivoxil and ceftibuten differ from the others in that they exhibit nonlinear pharmacokinetic properties. The nonlinear nature of these agents is reflected by decreasing maximal concentrations with escalating doses of cefixime and cefetamet pivoxil, decreasing area under the serum concentration-time curve with increasing doses for cefixime, and a reduced bioavailability with large doses of ceftibuten. Attention to such characteristics aid the clinician in selecting appropriate dosage regimens that will optimise drug absorption. The majority of agents are primarily renally eliminated; however, renal elimination accounts for only 20% of cefixime elimination. The pharmacokinetic parameters noted for the newer cephalosporins are not influenced by multiple-dose administration, suggesting lack of drug accumulation over time. The pharmacodynamics of antimicrobials should be considered when extrapolating pharmacokinetic information into the clinical arena. In the case of the beta-lactams, the time which drug concentrations remain above some critical threshold, such as the minimal inhibitory concentration, appears to have the greatest influence on bactericidal activity. Therefore, it is important to select dosage regimens that will optimise the time serum concentrations remain above this threshold. We present an evaluation of these agents with respect to their activity against a variety of pathogens in an effort to demonstrate a pharmacokinetically-based process of antimicrobial selection.

Oxidative metabolism of amsacrine by the neutrophil enzyme myeloperoxidase.

Oxidative metabolism of the anti-cancer drug amsacrine 4'-(9-acridinylamino) methane-sulphan-m-anisidide has been suggested to account for its cytotoxicity. However, enzymes capable of oxidizing it in non-hepatic tissue have yet to be identified. A potential candidate, that may be relevant to the metabolism of amsacrine in blood and its action in myeloid leukaemias and myelosuppression, is the haem enzyme myeloperoxidase. We have found that the purified human enzyme oxidizes amsacrine to its quinone diimine, either directly or through the production of hypochlorous acid. In comparison, the 4-methyl-5-methylcarboxamide derivative of amsacrine, CI-921 9-[[2-methoxy-4[(methylsulphonyl)-amino]phenyl]amino)-N, 5-dimethyl-4-acridine carboxamide, reacted poorly with myeloperoxidase, although it was oxidized by hypochlorous acid. Detailed studies of the mechanism by which myeloperoxidase oxidizes amsacrine revealed that the semiquinone imine free radical is a likely intermediate in this reaction. Oxidation of amsacrine analogues indicated that factors other than their reduction potential determine how readily they are metabolized by myeloperoxidase. Both amsacrine and CI-921 inhibited production of hypochlorous acid by myeloperoxidase. CI-921 acted by trapping the enzyme as the inactive redox intermediate compound II. Amsacrine inhibited by a different mechanism that may involve conversion of myeloperoxidase to compound III, which is also unable to oxidize Cl-. The susceptibility of amsacrine to oxidation by myeloperoxidase indicates that this reaction may contribute to the cytotoxicity of amsacrine toward neutrophils, monocytes and their precursors.

Metabolic potentiation of the radiosensitization of hypoxic bacterial cells afforded by nitroaromatic compounds.

Prolonged preirradiation incubation of nitroaromatic radiosensitizers with Escherichia coli cells has been found to increase the degree of radiosensitization of the cells in anoxia. Studies with E. coli strains which differ in their nitroreductase activity indicate that the increase in sensitization arises from the action of metabolites produced by the nitroreductase system of the cell. The metabolites alone appear to decrease the extrapolation number of irradiated hypoxic cells and when combined with the parent compound give a biphasic survival curve. The combination of misonidazole (1 mmole dm-3) and its metabolites (1 mmole dm-3) gave initial and final enhancement ratios of 2.4 and 1.4, respectively. The final enhancement ratio is that expected for 1 mmole dm-3 misonidazole alone, whereas the initial enhancement ratio indicates that the metabolites potentiate the action of misonidazole. The preirradiation incubation effect is removed by dithiothreitol at concentrations which do not affect the radiosensitization level of the nitroaromatic sensitizer. This result indicates that the active metabolite probably depletes a certain amount of the free-thiol compounds inside the cell which assist in the repair of radiation-induced damage.

Acute promyelocytic leukaemia and Hodgkin's disease in the same patient.

Acute non-lymphocytic leukaemia is a well recognised and increasingly reported complication of treated Hodgkin's disease. The prognosis is generally poor with a disappointing response to chemotherapy. A patient in whom myelodysplastic features appeared after treatment for Hodgkin's disease, to be followed shortly afterwards by acute promyelocytic leukaemia, is reported. Complete remission was achieved and sustained until Hodgkin's disease reappeared three years later when the patient was autografted with a marrow harvested four years earlier. The patient remains in good health with platelet support at the time of writing.

Cephalosporin-metronidazole combinations in the management of intra-abdominal infections.

With our current understanding of antimicrobial pharmacokinetics and pharmacodynamics, optimal antimicrobial dosing strategies can be developed for a variety infectious processes. Herein, we discuss the clinical utility of a combination containing a third-generation cephalosporin plus metronidazole as compared to conventional single agents (cefoxitin and ampicillin-sulbactam) for the management intra-abdominal infections. At present, several studies have been performed that compare the bactericidal activity of such combinations to that of single agents for organisms commonly isolated from these intra-abdominal process. From these studies it appears that the use of a third-generation cephalosporin with strong activity against common aerobic organisms associated with intra-abdominal infections in combination with a potent anaerobic drug such as metronidazole provides improved antibacterial activity and optimizes the pharmacodynamic profile of the agents over the dosing interval compared to conventional single agents. As a result of the pharmacokinetic and pharmaco-dynamic superiority of the combination regimen, considerable pharmacoeconomic advantages may be realized with the clinical implementation of a third-generation cephalosporin plus metronidazole regimen. This approach should result in maximal clinical efficacy and is important not only for individual patient therapy, but also for formulary management decisions.

Pharmacokinetics of cefotaxime in healthy volunteers and patients.

Cefotaxime is a third-generation cephalosporin that has maintained good susceptibility pattern despite its extensive use. It is available for intravenous and intramuscular administration. Its pharmacokinetic property includes a small volume of distribution with low protein binding. Cefotaxime's half-life is approximately 1.1 h, and it is primarily eliminated by the kidney. It has an active metabolite desacetyl-cefotaxime that displays pharmacokinetic properties similar to cefotaxime. Desacetyl-cefotaxime has a half-life of 1.5 h and also is eliminated by the kidneys by both glomerular filtration and active secretion. The half-life of cefotaxime and its metabolite is altered in patients with severe renal dysfunction requiring dosage adjustment. Despite its relatively short half-life, cefotaxime may be dosed every 12 h based on its pharmacokinetic and pharmacodynamic properties.

Absorption of ciprofloxacin in febrile and afebrile patients.

There are few studies evaluating the effect of fever on the bioavailability of oral antimicrobials. Owing to the growing interest in early conversion of febrile hospitalized patients from intravenous to oral therapy to reduce costs and avoid line sepsis, we evaluated the absorption of a single 500 mg dose of ciprofloxacin in 12 patients during an acute febrile episode and following defervescence. Patients able to take medication by mouth, oral temperature > or = 38.9 degrees C, and no known gastrointestinal disease were enrolled. Medications known to interact with the test agent were discontinued. Serum samples were obtained prior to and up until 12 h postdose. Pharmacokinetic parameters were obtained from the concentration-time profile using noncompartmental methods. The mean values for C(max) were 2.45 +/- 0.77 and 2.31 +/- 1.26 microg/ml, for T(max) 1.48 +/- 0.75 and 2.48 +/- 1.46 h, AUC(0-->infinity) 10.91 +/- 3.64 and 11.05 +/- 4.41 microg/ml h, and T (1 2 ) 4.05 +/- 0.65 and 4.08 +/- 0.76 h, respectively, for the febrile and afebrile periods. No statistically significant differences were observed between these parameters. We conclude that oral ciprofloxacin is well absorbed and is a suitable alternative to intravenous therapy in selected patients during an acute febrile illness.

Comparison of bactericidal activities of intermittent and continuous infusion dosing of vancomycin against methicillin-resistant Staphylococcus aureus and Enterococcus faecalis.

STUDY OBJECTIVE: To describe the pharmacokinetic profiles of vancomycin administered by continuous infusion and intermittent dosing and compare the duration of activity of the regimens. DESIGN: Randomized, open-label, crossover study. SETTING: Clinical research center at an academic medical center. SUBJECTS: Twelve healthy, nonpregnant volunteers age 27.6 +/- 2.3 years. INTERVENTION: Subjects received the following intravenous vancomycin regimens: 1 g every 12 hours; 2 g continuous infusion over 24 hours; and 1 g continuous infusion over 24 hours. Dosages were administered with and without gentamicin 2 mg/kg. MEASUREMENTS AND MAIN RESULTS: Serum samples were collected, drug concentrations determined, and bactericidal activity measured against two isolates each of methicillin-resistant Staphylococcus aureus and Enterococcus faecalis. Subjects had poor tolerability for continuous infusions. Trough concentration for the intermittent regimen was 5.5 +/- 1.9 mg/ml, and steady-state concentrations were 8.8 +/- 1.6 and 16.9 +/- 1.9 mg/ml for 1 and 2 g continuous infusions, respectively. In general, all regimens provided bactericidal activity throughout the study interval. Against one isolate of E. faecalis, 2 g continuous infusion plus gentamicin provided cidal activity for a significantly greater percentage of the dosing interval (p<0.001). CONCLUSION: Continuous infusion does not greatly improve the activity of vancomycin and should not be routinely administered. However, it may prove useful against isolates with reduced susceptibility to the agent.

Inactivation of xanthine oxidase by oxidative radical attack.

Steady-state radiolysis, pulse radiolysis and epr studies, combined with enzyme activity measurements, were carried out on the mechanism by which radical attack, through one-electron oxidation, inactivates xanthine oxidase. Electron transfer to both the N3 and Br2- radical species was used to initiate oxidative damage on the enzyme. Inactivation was found to occur to a greater extent at low than at high pH and is associated with the initial formation of a tryptophanyl radical which converts by a known intramolecular pathway to a tyrosyl radical with a rate constant of 5 x 10(3) S-1. The tyrosyl radical in turn slowly loses around half of its absorbance at an intramolecular rate constant of 350S-1 and is consistent with the establishment of a radical equilibrium with cysteine residue(s). The sequence of reactions could be repeated several times on the same irradiated sample implying that restitution of the implied cysteinyl radical occurs leading to other damage in the protein. N3+Trp/N-->Trp/N-->Tyr/O<-->Cys/S-->?. Epr evidence implies that inactivation of the enzyme from the above sequence of reactions arises in part from alternations to Fe/S center I in the enzyme.