ABCG2/BCRP transport mechanism revealed through kinetically excited targeted molecular dynamics simulations.

ABCG2/BCRP is an ABC transporter that plays an important role in tissue protection by exporting endogenous substrates and xenobiotics. ABCG2 is of major interest due to its involvement in multidrug resistance (MDR), and understanding its complex efflux mechanism is essential to preventing MDR and drug-drug interactions (DDI). ABCG2 export is characterized by two major conformational transitions between inward- and outward-facing states, the structures of which have been resolved. Yet, the entire transport cycle has not been characterized to date. Our study bridges the gap between the two extreme conformations by studying connecting pathways. We developed an innovative approach to enhance molecular dynamics simulations, 'kinetically excited targeted molecular dynamics', and successfully simulated the transitions between inward- and outward-facing states in both directions and the transport of the endogenous substrate estrone 3-sulfate. We discovered an additional pocket between the two substrate-binding cavities and found that the presence of the substrate in the first cavity is essential to couple the movements between the nucleotide-binding and transmembrane domains. Our study shed new light on the complex efflux mechanism, and we provided transition pathways that can help to identify novel substrates and inhibitors of ABCG2 and probe new drug candidates for MDR and DDI.

Target manufacturing by Spark Plasma Sintering for efficient 89Zr production.

Zirconium-89 (89Zr) is an emerging radionuclide for positron emission tomography (PET), with nuclear properties suitable for imaging slow biological processes in cellular targets. The 89Y(p,n)89Zr nuclear reaction is commonly exploited as the main production route with medical cyclotrons accelerating low-energy (< 20 MeV) and low-current (< 100 µA) proton beams. Usually, natural yttrium solid targets manufactured by different methods, including yttrium electrodeposition, yttrium sputtering, compressed yttrium powders, and foils, were employed. In this study, the Spark Plasma Sintering (SPS) technique has been investigated, for the first time, to manufacture yttrium solid targets for an efficient 89Zr radionuclide yield. The natural yttrium disc was bonded to a niobium backing plate using a commercial SPS apparatus and a prototype machine assembled at the University of Pavia. The resulting targets were irradiated in a TR19 cyclotron with a 12 MeV proton beam at 50 µA. A dedicated dissolution module, obtained from a commercial system, was used to develop an automated process for the purification and recovery of the produced 89Zr radionuclide. The production yield and recovery efficiency were measured and compared to 89Zr produced by irradiating standard yttrium foils. SPS manufactured targets withstand an average heat power density of approximately 650 W∙cm-2 for continuous irradiation up to 5 h without visible damage. A saturation yield of 14.12 ± 0.38 MBq/µAh was measured. The results showed that the obtained 89Zr production yield and quality were comparable to similar data obtained using standard yttrium foil targets. In conclusion, the present work demonstrates that the SPS technique might be a suitable technical manufacturing solution aimed at high-yield 89Zr radioisotope production.

[Implementation of a new gene therapy in ophthalmology: Regulatory and organizational issues]. / Mise en place d'une nouvelle thérapie génique en ophtalmologie : aspects réglementaires et organisationnels.

Voretigene neparvovec (VN) is the first gene therapy in ophthalmology for patients with RPE65-mediated hereditary retinal dystrophy. It has recently obtained European market approval, which is subject to strict regulatory and organizational conditions for its use. Here, we analyze the main studies supporting the authorization of this new therapy and describe the necessary steps to take at a hospital level for optimal administration to patients following current regulations.

[Drug interactions in an elderly population. Prospective assessment of their frequency and seriousness among 56 patients]. / Interactions médicamenteuses dans une population âgée.

OBJECTIVE: To assess the nature and the number of potential adverse drug interactions by analysis of outpatient prescriptions for elderly patients, of medications taken during the week before hospitalization in a general surgery department. METHOD: The study of 56 patients older than 65 years was conducted from November 2002 through February 2003. The outpatient prescriptions corresponding to medications taken during the 7 days before admission were analyzed by a pharmacy resident, who used data-processing tools and databases. RESULTS: Most patients (83%) knew the reason for their prescription. Thirteen (28%) reported using over-the-counter medication. Only 89% of the patients reported complete compliance with the prescription. The average age of the patients was 72.1 +/- 6.3 years and the median was 71 years [65-91]; 43% were women and 57% men. The 257 lines of prescriptions analyzed averaged 5.7 +/- 2.6 drugs (range: 2-10) per prescription. The average number of possible interactions was 3.1 +/- 2.8 per prescription for a total of 89 listed potential interactions. The levels observed were 3 warnings (3%), 37 precautions (42%) and 49 possible adverse interactions (55%). No contraindication was noted. The drugs mentioned most often were benzodiazepines, diuretics, conversion enzyme inhibitors, angiotensin II inhibitors, and beta-blockers. The potential risks most often found were hypotension, depression of the central nervous system, hypoglycemia and acute renal failure. The drug interactions were mainly due to the accumulation of the effects of separate drug classes. Deterioration in renal function was often noted as plasma concentration of the second drug increased. DISCUSSION: This exploratory study shows the reality of the iatrogenic risk for elderly patients. This analysis of outpatient prescriptions is consistent with findings in the literature. Analysis of interactions is conducted on a pairwise basis. It is thus difficult to envisage the consequences of the association of 5 or more drugs in patients with complex illnesses and diminished physiological and metabolic capacity. Patient files kept by the pharmacist could provide information about individual combinations ofthe prescription and over-the-counter drugs.

Stability of doxorubicin combined with Radioselectan, a contrast agent, for chemoembolization.

OBJECTIVE: To assess the stability of doxorubicin combined with Radioselectan. METHODS: Solutions of doxorubicin 5 mg/mL were prepared from commercially available 50 mg powder with 10 mL of Radioselectan. They were stored in glass syringes at 4, 25 and 45 degrees C. The concentrations of doxorubicin were determined using a stability-indicating high-performance liquid chromatography method. The initial and final pHs of solutions were compared. The times (t90) needed for doxorubicin to fall to 90% of its initial concentration were calculated by a linear regression analysis. RESULTS: The t90 [95% confidence limits] were 79 [75-83], 56 [53-59] and 22 [21-23] hours for the solutions stored at 4, 25 and 40 degrees C respectively. The initial pH of the solutions stored at 4, 25 and 40 degrees C were 6.52, 6.50 and 6.51 respectively. The final pH of solutions stored at 25 and 40 degrees C decreased significantly by 0.3 and 0.9 respectively. No change of pH solution stored at 4 degrees C was observed. CONCLUSION: Doxorubicin combined with Radioselectan stored at room temperature is stable for 48 h.

Stability of fludrocortisone acetate solutions prepared from tablets and powder.

To assess the stability of fludrocortisone acetate oral solutions prepared from tablets and powder at three temperatures over a 60-days period. Solutions of fludrocortisone acetate 40 microg/ml were prepared from commercially available 0.05-mg tablets and powder in ethanol 17% v/v. They stored in an amber glass prescription bottles at +4, +23 and +40 degrees C shielded from light. The concentrations of fludrocortisone acetate were determined in duplicate by high-performance liquid chromatography at 0, 1, 7, 14, 30, 50 and 60 days. The initial and final pH of solutions were compared. The recovery of fludrocortisone acetate from tablets was determined. The times (t(90)) needed for fludrocortisone acetate to fall to 90% of it's initial concentration were calculated by a linear regression analysis to allow the determination of the expired dates. The recovery of fludrocortisone acetate from tablets was 78 +/- 3%. The t(90) expressed with 95% confidence limits were 2 +/- 1 and 22 +/- 3 days for the solutions prepared from tablets and stored at +23 and +4 degrees C, respectively, whereas t(90) were 11 +/- 2 days and at least 60 days for the solutions prepared with the powder and stored at +23 and +4 degrees C, respectively. No color or odour changes were observed during the study period. The initial pH of the solutions prepared from tablets and powder were 7.7 and 6.9, respectively. No change of pH values was observed at the end of the 60 days. Significant degradation of fludrocortisone acetate occurred in formulations stored at +23 degrees C. Fludrocortisone acetate 40 microg/ml solutions prepared from tablets and powder were stable 19 days and at least 60 days, respectively, when stored at +4 degrees C. The solution prepared from powder is the best in term of stability and final concentration which is independent on the fludrocortisone acetate recovery.

Screening of multidrug-resistance sensitive drugs by in situ brain perfusion in P-glycoprotein-deficient mice.

PURPOSE: This study was conducted to assess the influence of P-glycoprotein (P-gp) on brain uptake of multidrug resistance sensitive drugs using an in situ brain perfusion technique in P-gp-deficient (mdr1a[-/-]) and wild-type mice. METHODS: The blood-brain transport of radiolabeled vinblastine, vincristine, doxorubicin, colchicine, and morphine was evaluated in mdr1a(-/-) and wild-type CF-1 mice with the in situ brain perfusion technique. Brain uptake of drugs after intravenous pretreatment with P-gp reversal agents, (PSC 833, GF 120918, or (+/-)-verapamil), or vehicle also was studied in wild-type mice. In all experiments, cerebral vascular volume was determined by co-perfusion of sucrose. RESULTS: Cerebral vascular volume was preserved during perfusion, indicating maintenance of blood-brain barrier integrity in both types of mice within the concentration range of substrates in the perfusate. The apparent brain transport of colchicine. vinblastine, doxorubicin, and morphine was increased 3.0, 2.7, 1.5, and 1.4-fold, respectively, in mdr1a(-/-) mice compared with the wild-type: the brain uptake of vincristine was not affected by P-gp. Preadministration of PSC 833 or GF 120918 in wild-type mice led to a -3-fold increase in the brain transport of colchicine and vinblastine, but no effect was observed for the other compounds. Intravenous verapamil enhanced colchicine brain transport (1.8-fold), but failed to increase the brain uptake of vinblastine and morphine. CONCLUSION: The in situ brain perfusion technique appears to be a sensitive and powerful tool for medium throughput screening of the brain uptake of multidrug resistance sensitive drugs. The effect of P-gp is characterized more efficiently with mdr1a(-/-) mice than by using modulators of P-gp in wild-type mice.

[Laparoscopic appendectomy as first choice intervention in the treatment of inflammatory diseases of the appendix. Analysis of 397 laparoscopic interventions]. / L'appendicectomia laparoscopica come intervento di scelta nel trattamento delle malattie infiammatorie dell'appendice. Analisi di 397 interventi laparoscopici.

Despite the increasingly widespread use of laparoscopy, especially for gallbladder diseases, laparoscopic appendectomy has not yet met with universal acceptance. The aim of the present retrospective study was to illustrate the technical aspects and the results of 397 laparoscopic appendectomies carried out at the Surgical Department of the San Giovanni Battista Hospital in Zagarolo, Rome, from January 1993 to December 2000. The patients included 260 females with a mean age of 35.5 years and 137 males with a mean age of 38.5 years. All the appendectomies were carried out laparoscopically, with a conversion index of 0%, by two surgeons, utilising only three trocars and the Veress needle technique. Mean operating time was 22.5 min (range: 15-30 min). The mean postoperative hospital stay was 1.5 days. Morbidity was 1.76% (7 cases) and mortality nil. The authors emphasise the numerous advantages of laparoscopic techniques in their experience, including the excellent cosmetic results, reduced postoperative pain, rapid functional recovery, and lower incidences of adhesions, wound infections and laparocele, and believe that laparoscopic appendectomy is a reliable operation for treating all inflammatory diseases of the appendix.

[Videolaparoscopic treatment of varicocele: retrospective study of 165 cases]. / Trattamento videolaparoscopico del varicocele: studio retrospettivo su 165 casi.

Idiopathic varicocele is a common condition that is present in approximately 15% of the general male population. The mechanism by which varicocele exerts a deleterious effect on testicular function and semen quality remains unknown. Nevertheless, it is generally regarded as a significant factor in male infertility. Varicocelectomy is accomplished with a variety of approaches: the inguinal and high retroperitoneal procedures are still commonly accepted methods, but laparoscopic varicocelectomy is currently proving an increasingly popular procedure. The authors report the results of a retrospective study of 165 laparoscopic varicocelectomies performed from 1993 to 2000 and conclude that this approach is simple, safe and effective and should be recommended as the treatment of choice.

[Phlebodynamometry in the study of venous insufficiency of the lower limbs]. / La flebodinamometria nello studio dell'insufficienza venosa degli arti inferiori.

BACKGROUND: The significance of ambulatory venous pressure measurement in the diagnosis of chronic venous insufficiency of the lower limbs is evaluated. METHODS: 190 limbs of 120 outpatients were investigated from 1991 through 1997; the study was performed whenever clinical and ultrasound evaluation did not allow to establish the diagnosis of "simple varices". The technique standardized according to Nicolaides was followed. RESULTS AND CONCLUSIONS: The results of the study confirm the importance of ambulatory venous pressure measurement in the differential diagnosis of chronic venous hypertension of the lower limbs, especially when caused by vein compression, as well as in the follow-up of these patients when submitted to surgical treatment.

Population pharmacokinetics of methotrexate in the guinea pig.

The population pharmacokinetics of an antitumoral and antiinflammatory agent, methotrexate (MTX), a folic acid antagonist, was studied in guinea pigs. Animals received an acute intraperitoneal injection of 0.25, 1 or 5 mg/kg MTX. Blood sampling was carried out for 12 hrs. after MTX administration and plasma drug concentrations were measured by fluorescence polarization immunoassay. The pharmacokinetic (PK) parameters were computed using the bayesian population model. MTX reached the level of detection at 3 hrs. for the animals injected with the lowest dose (0.25 mg/kg), at 3.5 hrs. for those animals which had the intermediate dose (1 mg/kg) and more than 6 hrs. for animals having received the highest dose (5 mg/kg). Each kinetic parameter (half life, total clearance - CLt, volume of distribution at steady state - VDSS, mean residence time - MRT - and area under curve - AUC) didn't show any significant difference between doses. MTX kinetic was linear for the first two doses (0.25 and 1 mg/kg MTX) and non-linear thereafter. MTX presented a one compartment distribution.

Determination of cisapride and norcisapride in human plasma using high-performance liquid chromatography with ultraviolet detection.

A simple, rapid and reproducible high-performance liquid chromatographic assay for cisapride and norcisapride in human plasma is described. Samples of plasma (150 microl) were extracted using a C18 solid-phase cartridge. Regenerated tubes were eluted with 1.0 ml of methanol, dried, redissolved in 150 microl of methanol and injected. Chromatography was performed at room temperature by pumping acetonitrile-methanol-0.015 M phosphate buffer pH 2.2-2.3 (680:194:126, v/v/v) at 0.8 ml/min through a C18 reversed-phase column. Cisapride, norcisapride and internal standard were detected by absorbance at 276 nm and were eluted at 4.3, 5.3 and 8.1 min, respectively. Calibration plots in plasma were linear (r>0.998) from 10 to 150 ng/ml. Intraday precisions for cisapride and norcisapride were 3.3% and 5.4%, respectively. Interday precisions for cisapride and norcisapride were 9.6% and 9.0%, respectively. Drugs used which might be coadministered were tested for interference.

[Entrapment syndrome of the popliteal vein: results of the surgical treatment]. / La sindrome da intrappolamento della vena poplitea: risultati del trattamento chirurgico.

Entrapment of the popliteal vein has been rarely reported. Purpose of the present study was to evaluate the long-term results of vein decompression in the popliteal vein entrapment syndrome. Between August 1986 and June 1994, 35 patients (49 limbs) were operated on for popliteal vein entrapment syndrome at our Institution. There were 28 female and 7 male (mean age 44.5 +/- 13.5 years). Seven limbs had associated a popliteal artery entrapment syndrome. Twenty-three (49.6%) limbs presented with skin changes ascribed to venous disease. Preoperative diagnosis consisted on Doppler CW, Duplex Scan, venography and ambulatory venous pressure measurements. Surgical management consisted on the division of the anomalous structure causing entrapment. In 35 (71.4%) limbs subfascial ligation of perforating veins was associated. The patients were followed-up (mean 61 +/- 7 months) with venography and AVP. No deaths occurred and morbidity was 14.3%. Doppler CW and Duplex Scan were not accurate to diagnose the entrapment. Ambulatory venous pressure and venography accurately diagnosed the syndrome. Age and preoperative status did not affect long-term results (p = NS). Long-term operative success was negatively influenced by associated procedures for ligation of perforating veins (p < 0.03). Popliteal vein entrapment syndrome should be early diagnosed to prevent incompetence of perforating veins. Surgical treatment of cases not requiring ligation of perforating veins had a better long-term success rate. Treatment at later stages allows symptom amelioration but does not prevent the consequences of a long-standing chronic venous disease.

[The use of the jejunum free flap in the reconstruction of the oral cavity]. / Il lembo rivascolarizzato di digiuno nella ricostruzione del cavo orale.

The rapid development of surgical techniques in the head and neck area has greatly assisted in enabling reconstructive surgery to bring about prompt positive results. Radical tumor excision alone is no longer an acceptable treatment. Through new reconstructive techniques, psychological and social isolation of the patients, due to difficulties in such vital functions as chewing, speech, swallowing and breathing, can be reduced remarkably. In the past numerous techniques which employed myocutaneous flaps in the reconstruction of the oropharynx have been described. During the last ten years, however, many Authors have proposed the use of free flaps for this reconstructive surgery. Our Department presents its personal experience in reconstruction of the oral cavity using the jejunal flap, which facilitates superior physiological and histological adaptation when compared to that had with other flaps. Our histological study shows metaplastic transformation of the columnar epithelium into squamous epithelium (similar to oral cavity epithelium), phenomenon already observed in "cervix uteri" and anorectal area. The primary reconstruction with a free revascularized jejunal loop associated with mandibular replacement offers certain significant advantages such as satisfactory reconstruction of large defects, high flexibility of the flap and a productions of mucous which cleans the surface of transplants. Furthermore, the mesenteric foot tissue serves as good transplant material for extended soft-tissue loss. In agreement with a Study begun by Carrel in 1906 and that of Reuther (1982), we believe that reconstruction of large defects in the oral cavity by means of transplantation of the mucosa is the ideal treatment.

[Magnetic resonance imaging of the esophagus with lumen opacification using a specific contrast agent]. / Studio dell'esofago con risonanza magnetica con opacizzazione del lume mediante impiego di un mezzo di contrasto specifico.

A new contrast agent has been developed for the opacification of the esophageal lumen in Magnetic Resonance (MR) Imaging. The contrast agent consists of an emulsion of low-density and high-viscosity barium paste employed for the CT study of the esophagus (E.Z.E.M., Westbury, USA) and a small amount of Gadolinium-DTPA (Magnevist, Schering, Germany), diluted in 3 ml of saline solution. In vitro evaluation of the contrast solution showed high-signal intensity on T1-weighted SE sequences. The study was subsequently performed on 5 healthy volunteers and 30 subjects with clinical indication for MR Imaging of the chest. The complete opacification of the esophagus was obtained in 12 of the 16 patients (75%) who presented no pathological involvement of the esophagus. The esophageal lumen was completely opacified in 8 patients with esophageal carcinoma and in 1 case of esophageal leiomyoma. In the cases with esophageal carcinoma, lumen opacification allowed the evaluation of tumor growth (concentric or eccentric), a more detailed definition of tumor extent, with assessment of neoplastic wall thickening, and the evaluation of the possible infiltration of adjacent organs. Lumen opacification was obtained in 8 of 10 patients (80%) affected with other chest conditions secondarily involving the esophagus. In these cases, lumen opacification helped to localize the esophagus and to evaluate its involvement by adjacent tumors.

[Magnetic resonance in the diagnosis of thyroid diseases]. / La Risonanza Magnetica nella diagnostica delle malattie della tiroide.

Previous clinical experience in the study of the soft tissues of the neck region has pointed out the accuracy of MRI in terms of high definition and contrast resolution. Seventy-seven patients with thyroid diseases were examined to define the possible role of MRI in the diagnosis of these conditions. In the patients affected with thyroiditis, MR findings were not specific, showing increased glandular volume and signal inhomogeneity. MR examinations of struma allowed an accurate evaluation of glandular size; furthermore, more information was obtained than with other imaging modalities in the cases with mediastinal involvement. On T2-weighted images, adenomas were always hyperintense, whereas variable signal intensity was seen on T1-weighted scans, with the exception of Hürthle cell adenomas, which were hyperintense on both T1- and T2-weighted sequences. MRI proved to be reliable in the depiction of tumor spread at both glandular and extraglandular levels. The distinction between scar fibrosis and relapse was also possible, in the cases undergoing postoperative follow-up. In conclusion, MRI emerges as a diagnostic tool complementary to other imaging techniques. However, in selected conditions--e.g., mediastinal struma and tumors--and in the postoperative follow-up, MRI can be considered the method of choice.