Comparative study of laser versus radiofrequency myringotomy in rabbits: The effectiveness of mitomycin C application.

OBJECTIVE: To compare laser-assisted tympanostomy (LAT) with radiofrequency myringotomy (RFM), as well as the effectiveness of mitomycin C (MC) on the above techniques, in rabbits. STUDY DESIGN: Experimental animal research protocol. SETTING: University of Crete, School of Medicine, Medical Experimental Education and Research Center. METHODS: Bilateral myringotomies were performed under general anesthesia on 40 rabbits. LAT was performed on 20 animals (40 ears) and RFM on the remaining 20 animals (40 ears). MC (0.3 mg/mL) pledgets were applied to the right ears and saline pledgets to the left ears. Animals were monitored weekly using otomicroscopy until myringotomy closure. Kaplan-Meier survival techniques were used to compare myringotomy patency times. INTERVENTIONS: Under general anesthesia, bilateral LAT was performed on 20 rabbits and bilateral RFM on 20 rabbits. MAIN OUTCOME MEASURES: Myringotomy patency time. RESULTS: The mean patency times of the saline-treated ears were: 1.85 weeks (95% confidence interval [CI], 1.556-2.144 wk) for the LAT group and 1.70 weeks (95% CI, 1.494-1.906 wk) for the RFM group. This difference was not significant (p > 0.5). MC application significantly prolonged mean patency time (p < 0.0001) in both LAT and RFM groups. The mean patency times in the MC-treated ears were 5.45 weeks (95% CI, 5.226-5.674 wk) for the LAT group and 5.55 weeks (95% CI, 5.285-5.815 wk) for the RFM group. This difference was not significant (p > 0.5). CONCLUSION: There is no significant difference in myringotomy patency times between LAT and RFM techniques in rabbits, whereas MC significantly prolongs the patency rate of either technique.     

Prolonged exposure of intraocular lens implant with preservation of globe integrity and visual function.

A 70-year-old woman had corneal ulcer and melting after complicated cataract surgery with polymethylmethacrylate lens implant insertion. A conjunctival flap was initially used to cover the defect with a plan to perform keratoplasty later. Fifteen months postoperatively, she presented with total absence of central corneal tissue and iris and exposure of the implant. The eye was not inflamed, painful, or hard on palpation and visual acuity was counting fingers at 3 m. The preservation of globe integrity despite exposure of the polymethylmethacrylate implant implies a stable adhesion between polymethylmethacrylate and residual corneal tissue and may prove useful in keratoprosthesis design.     

The Hemodynamic Mechanisms of Lung Injury and Systemic Inflammatory Response Following Brain Death in the Transplant Donor

Brain-dead donors are the major source of lungs for transplantation. Brain death is characterized by two hemodynamic phases. Initially, massive sympathetic discharge results in a hypertensive crisis. This is followed by neurogenic hypotension. Up-regulation of pro-inflammatory mediators occurs in all organs and lung injury develops; this can adversely affect graft function post-transplantation. The mechanisms of the systemic and lung inflammation are unknown. We hypothesized that the hemodynamic changes are responsible for these inflammatory phenomena. Brain death was induced by intra-cranial balloon inflation in rats. This resulted in hypertensive crisis, followed by hypotension. There was a significant increase in blood neutrophil CD11b/CD18 expression and pro-inflammatory cytokine levels in serum and bronchoalveolar lavage, compared with control animals. Rupture of the capillary-alveolar membrane was demonstrated by electron microscopy. Elimination of the hypertensive response by α-adrenergic antagonist pre-treatment prevented inflammatory lung injury, reduced the systemic inflammatory markers and preserved capillary-alveolar membrane integrity. Correction of the neurogenic hypotension with noradrenaline ameliorated the systemic inflammatory response and improved oxygenation. We conclude that the sympathetic discharge triggers systemic and lung inflammation, which can be further enhanced by neurogenic hypotension. Management of the brain-dead donor with early anti-inflammatory treatment and vasoconstrictors is warranted.     

Monitoring motor function during resection of tumours in the lower brain stem and fourth ventricle

Objectives Even in the days of modern microsurgery, the removal of a brain stem lesion remains a surgical challenge. Especially when operating on children, the prognosis is directly related to the radicality of the resection; however, a radical resection is often associated with surgical morbidity. Intraoperative neuromonitoring could help to minimise the surgical morbidity, but few studies have been performed to clarify the value of this monitoring. We investigated a prospective series of 21 patients with lesions involving the brain stem for the prognostic value and benefits of neuromonitoring.Methods We performed intraoperative neuromonitoring of cranial nerve function by electromyography (EMG) and motor evoked potential (MEP). The results were correlated with postoperative neurological deficits.Conclusions There is a good correlation between intraoperative neurophysiological events and postoperative neurological deficits in patients with lesions of the brain stem. In general, transient, prolonged, spontaneous activity in EMG is associated with a transient paresis of the respective muscle, whereas a permanent spontaneous activity is associated with a permanent deficit. Intraoperative neuromonitoring reliably predicts postoperative neurological function in patients with tumours of the lower brain stem and fourth ventricle. This neuromonitoring guides the neurosurgeon in the operation and may decrease surgical morbidity. We recommend using monitoring of MEP and EMG of the lower cranial nerves in surgery on all patients with lesions involving the lower brain stem and fourth ventricle.     

Increased incidence of papillary thyroid cancer among total thyroidectomies in Crete.

OBJECTIVE: To investigate the increased incidence of papillary thyroid cancer as found in specimens of total thyroidectomies and potential correlation with etiological factors. STUDY DESIGN AND SETTING: A retrospective study on patients who underwent total thyroidectomy, from 1990 to 2004, in an academic tertiary referral medical center. Patients' records were placed in a database, which included medical condition, history, and demographics. Histopathological slides were reviewed with special focus on papillary cancer. RESULTS: Our series consisted of 2379 patients. Thyroid cancer was confirmed in 354 patients (14.88%). Papillary carcinoma represented the most frequent type (316 patients, 89.26%). Increased incidence of papillary carcinomas was noticed after 1995, reaching the maximum value in the year 2000. After 2000, there was a descending trend and then a plateau. CONCLUSION: The increased incidence of papillary thyroid cannot be attributed to dietary patterns or increased diagnostic and therapeutic activity. It is likely to be associated with increased radiation and may be associated with the Chernobyl fallout.     

Peripheral-type benzodiazepine receptor (PBR) gene amplification in MDA-MB-231 aggressive breast cancer cells

Recent studies using human breast cancer cell lines, animal models, and human tissue biopsies have suggested a close correlation between the expression of the peripheral-type benzodiazepine receptor (PBR) and the progression of breast cancer. This study investigates the genetic status of the PBR gene in two human breast cancer cell lines: MDA-MB-231 cells, which are an aggressive breast cancer cell line that contains high levels of PBR, and MCF-7 cells, which are a nonaggressive cell line that contains low levels of PBR. Both DNA (Southern) blot and fluorescence in situ hybridization analyses indicate that the PBR gene is amplified in MDA-MB-231 relative to MCF-7 cells. These data suggest that PBR gene amplification may be an important indicator of breast cancer progression.     

Hyper immunoglobulin M syndrome due to CD40 deficiency: clinical, molecular, and immunological features

Summary: CD40 is a member of the tumor necrosis factor receptor family, which is expressed by a variety of cells including B cells, macrophages, dendritic cells, and other nonimmune cell types. CD40 activation is critical for B‐cell proliferation, immunoglobulin (Ig)‐isotype switching, and germinal center formation. In physiological conditions, the activation of CD40 occurs by binding to its natural ligand, CD154, which is expressed on activated T cells. The in vivo critical role of CD40–CD154 interaction on B‐cell differentiation and isotype switching is provided by the discovery that mutations in either CD40 or CD154 gene cause the hyper IgM syndrome, termed HIGM3 or HIGM1, respectively, characterized by very low levels of serum IgG, IgA, and IgE, with normal or elevated IgM, associated with a defective germinal center formation. Originally considered humoral primary immunodeficiencies, the clinical features and the defect of T‐cell priming, resulting from a defective T–B cell or dendritic cell interaction, is now considered as combined immunodeficiencies. In this article, we present a comprehensive overview of the clinical, genetic, and immunological features of patients with hyper IgM syndrome due to CD40 mutations.     

Effect of fibronectin- and collagen I-coated titanium fiber mesh on proliferation and differentiation of osteogenic cells

The objective of this study was to evaluate the effects of fibronectin and collagen I coatings on titanium fiber mesh on the proliferation and osteogenic differentiation of rat bone marrow cells. Three main treatment groups were investigated in addition to uncoated titanium fiber meshes: meshes coated with fibronectin, meshes coated with collagen I, and meshes coated first with collagen I and then subsequently with fibronectin. Rat bone marrow cells were cultured for 1, 4, 8, and 16 days in plain and coated titanium fiber meshes. In addition, a portion of each of these coating treatment groups was cultured in the presence of antibodies against fibronectin and collagen I integrins. To evaluate cellular proliferation and differentiation, constructs were examined for DNA, osteocalcin, and calcium content and alkaline phosphatase activity. There were no significant effects of the coatings on cellular proliferation as indicated by the DNA quantification analysis. When antibodies against fibronectin and collagen I integrins were used, a significant reduction (p < 0.05) in cell proliferation was observed for the uncoated titanium meshes, meshes coated with collagen, and meshes coated with collagen and fibronectin. The different coatings also did not affect the alkaline phosphatase activity of the cells seeded on the coated meshes. However, the presence of antibodies against fibronectin or collagen I integrins resulted in significantly delayed expression of alkaline phosphatase activity for uncoated titanium meshes, meshes coated with collagen, and meshes coated with collagen and fibronectin. Calcium measurements did not reveal a significant effect of fibronectin or collagen I coating on calcium deposition in the meshes. Also, no difference in calcium content was observed in the uncoated titanium meshes and meshes coated with fibronectin when antibodies against fibronectin or collagen I integrins were present. Meshes coated with both collagen I and fibronectin showed significantly higher calcium content when cultured in the presence of antibodies to collagen and fibronectin integrins. A similar phenomenon was also observed for collagen-coated meshes cultured in the presence of antibodies to fibronectin integrins. No significant differences in osteocalcin content were observed between the treatment groups. However, all groups exposed to antibodies against fibronectin integrins showed a significant decrease in osteocalcin content on day 16. These results show that a fibronectin or collagen I coating does not stimulate the differentiation of rat bone marrow cells seeded in a titanium fiber mesh.     

Preclinical pharmacology of the antitumor agentO-6-methylguanine in CDF1 mice

O-6-methylguanine (O6-mG), a guanine analog recently shown to be a potent inhibitor of alkylguanine-DNA alkyltransferase, has been found to potentiate the antitumor activity of nitrosoureas, in particular, carmustine (BCNU), in resistant cell lines (HT-29 mer+) and is targeted for development as a modulating agent with chloroethyl nitrosoureas. A high-performance liquid chromatography (HPLC) assay of O6-mG in plasma has been developed using a C18 reverse-phase column. O6-mG and the internal standard deoxyguanosine (dGuo) were eluted with a linear gradient of from 15% to 35% methanol in 0.5M ammonium acetate (pH 6.5) at a flow rate of 1 ml/min. The assay was linear over a 4-log concentration range with a detection limit of 0.1 g/ml. The within-run and between-run coefficients of variation (CV) were found to be 8.1% and 9.3%, respectively. The pharmacokinetics (PK) of O6-mG were investigated in healthy CDF1 mice following separate i.v. and i.p. administrations. At 20 mg/kg i.v., plasma O6-mG gave a biexponential profile with a terminal half-life (t_1/2) of 24 min and a total clearance (CLT) of 23.7 ml min^–1 kg^–1. Higher doses (40–80 mg/kg) revealed a fluctuating third phase, probably due to enterohepatic cycling. Dose-dependent kinetics as measured by CLT and area under the plasma-concentration curve (AUC) values were also seen. Following i.p. dosing, O6-mG was completely absorbed and available to the circulation. No acute toxicity was observed in the animals, except for mild sedation, a possible side effect of the 10% ethanol used in the formulation. Studies on the cellular metabolism of highly purified [³H]-O6-mG have shown that the compound is not anabolized by a human lymphoblastoid cell line (CEM). Biochemistry studies have shown that the parent molecule is inactivating the alkylguanine-DNA alkyltransferase (AGT), thus exerting its pharmacological effect.Abbreviations O6-mG O-6-methylguanine - HPLC high-performance liquid chromatography - PK pharmacokinetics - CLT total clearance - AUC area under the plasma concentration curve - AGT alkylguanine-DNA alkyltransferase - dGuo deoxyguanosine This work was supported in part by contract NO1-CM-97620 from the National Cancer Institute (NIH) and by the Neil Bogart Memorial Laboratories by the T. J. Martell Foundation for Cancer, Leukemia, and AIDS Research     

Asparaginase pharmacokinetics after intensive polyethylene glycol-conjugated L-asparaginase therapy for children with relapsed acute lymphoblastic leukemia.

PURPOSE: Asparaginase therapy is an important component in the treatment of children with acute lymphoblastic leukemia. Polyethylene glycol-conjugated asparaginase (PEG-ASNase) has significant pharmacological advantages over native Escherichia coli asparaginase. We investigated the pharmacokinetics of PEG-ASNase, presence of antibodies to PEG-ASNase, and concentrations of asparagine in serum and cerebrospinal fluid (CSF) in combination chemotherapy for relapsed pediatric acute lymphoblastic leukemia. EXPERIMENTAL DESIGN: Twenty-eight pediatric patients with relapsed medullary (n = 16) and extramedullary (n = 11) acute lymphoblastic leukemia were enrolled at three pediatric institutions and had at least two serum and CSF samples obtained for analysis. Patients received induction therapy (including PEG-ASNase 2500 IU/m2 intramuscularly weekly on days 2, 9, 16, and 23) and intensification therapy (including PEG-ASNase 2500 IU/m2 intramuscularly once on day 7). Serum samples were obtained weekly during induction and intensification. CSF samples were obtained during therapeutic lumbar punctures during induction and intensification. RESULTS: Weekly PEG-ASNase therapy resulted in PEG-ASNase activity of >0.1 IU/ml in 91-100% of patients throughout induction. During intensification, PEG-ASNase on day 7 resulted in PEG-ASNase activity >0.1 IU/ml in 94% and 80% of patients on days 14 and 21, respectively. Serum and CSF asparagine depletion was observed and maintained during induction and intensification in the majority of samples. PEG-ASNase antibody was observed in only 3 patients. CONCLUSIONS: Intensive PEG-ASNase therapy in the treatment of relapsed acute lymphoblastic leukemia reliably results in high-level serum PEG-ASNase activity, and asparagine depletion in serum and CSF is usually achieved. Incorporation of intensive PEG-ASNase in future trials for recurrent acute lymphoblastic leukemia is warranted.