Pharmaceutical development and manufacturing of a parenteral formulation of a novel antitumor agent, VNP40101M.
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The objective of this study was to develop and manufacture a stable parenteral formulation for Phase I clinical trials of VNP40101M (1,2-Bis(methylsulfonyl)-1-(2-chloroethyl)-2-[(2-methylamino)carbonyl] hydrazine), a novel antitumor agent. The solubility and stability of the drug was determined. Solubility studies suggested that VNP40101M exhibited poor aqueous solubility but showed appreciable solubility in nonaqueous solvents. The aqueous solubility of the drug could not be increased by adjusting the pH. At a pH above 7, base-catalyzed decomposition of VNP40101M occurred. The low octanol-water partition coefficient of 0.75 suggested poor solubility in lipophilic solvents. Based on these preformulation observations, a parenteral formulation containing 10 mg/mL of VNP40101M was prepared in a solvent system consisting of 30% ethyl alcohol and 70% polyethylene glycol-300 (PEG-300). To minimize base-catalyzed hydrolytic degradation, citric acid at 0.6% concentration was included to acidify the formulation. Rubber closures, filter membranes, and liquid transfer tubing were selected on the basis of compatibility studies and absence of loss of drug due to adsorption of these components. The formulation was subjected to accelerated stability studies and dilution studies with large volume parenteral (LVP) solutions, normal saline, and 5% dextrose injection (D5W). The results of the dilution study indicated that the formulation could be diluted in these solutions up to 2 mg/mL for 8 hours without drug precipitation and degradation. Accelerated stability studies suggested that the product should be kept at 2 degrees C to 8 degrees C for long-term storage. The developed formulation was successfully scaled up and manufactured for use in clinical trials. (+info)
Use of studded Polyflex stents in patients with neoplastic obstructions of the central airways.
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BACKGROUND: The Polyflex is a commercially available silastic airway stent with proven efficacy. Due to a smooth outer surface its anchorage in the airway wall is superficial which may lead to stent migration. OBJECTIVE: To study the performance of an newer version of the Polyflex stent with a studded outer surface, which should improve anchorage. METHODS: In a 5-centre international study the new stent was prospectively tested in symptomatic patients with neoplastic central airway stenosis of more that 50% of normal diameter. Insertion technique, efficacy of stent placement and stent-related complications were recorded before, 1 month and 3 months post stent placement. RESULTS: Under general anaesthesia and rigid bronchoscopy 27 stents were inserted in 26 patients, mean age: 62 years (range: 37-83), 16 men. Diagnoses were 18 bronchogenic carcinoma, 4 oesophageal carcinoma, 2 metastases, 1 tracheal carcinoma, and 1 schwannoma. The stents were inserted in the following locations: 10 right main bronchus, 8 left main bronchus, 7 trachea, and 2 tracheo-bronchial. There was significant improvement in all functional parameters assessed from before (A), to 1 month (B) and 3 months (C) after stent placement. The measured values (mean +/- SD) were for the WHO scale: A: 2.7 (0.8), B: 1.5 (0.9), C: 1.6 (1.0); for the Karnofsky scale: A: 44 (19), B: 72 (18), C: 71 (21); for the Dyspnoea Index: A: 3.3 (0.7), B: 1.5 (0.8), C: 1.9 (1.2); for FEV(1): A: 1.2 (0.5), B: 1.9 (0.6), C: 1.5 (0.5), and for FVC: A: 2.1 (0.7), B: 2.8 (0.7), C: 2.5 (1.0). Stent-related complications were 4 reversible stent obstructions by secretions, 1 migration. The observation period was mean 4.3 months (range 2 days to 23 months). CONCLUSION: The studded Polyflex showed excellent efficacy, was very well tolerated, and had a very low migration rate. It presents an improvement over the older smooth model and can be considered a true alternative to the most widely used silastic stent, the Dumon stent. (+info)
Light-adjustable lens.
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PURPOSE: First, to determine whether a silicone light-adjustable intraocular lens (IOL) can be fabricated and adjusted precisely with a light delivery device (LDD). Second, to determine the biocompatibility of an adjustable IOL and whether the lens can be adjusted precisely in vivo. METHODS: After fabrication of a light-adjustable silicone formulation, IOLs were made and tested in vitro for cytotoxicity, leaching, precision of adjustment, optical quality after adjustment, and mechanical properties. Light-adjustable IOLs were then tested in vivo for biocompatibility and precision of adjustment in a rabbit model. In collaboration with Zeiss-Meditec, a digital LDD was developed and tested to correct for higher-order aberrations in light-adjustable IOLs. RESULTS: The results establish that a biocompatible silicone IOL can be fabricated and adjusted using safe levels of light. There was no evidence of cytotoxicity or leaching. Testing of mechanical properties revealed no significant differences from commercial controls. Implantation of light-adjustable lenses in rabbits demonstrated- excellent biocompatibility after 6 months, comparable to a commercially available IOL. In vivo spherical (hyperopic and myopic) adjustment in rabbits was achieved using an analog light delivery system. The digital light delivery system was tested and achieved correction of higher-order aberrations. CONCLUSION: A silicone light-adjustable IOL and LDD have been developed to enable postoperative, noninvasive adjustment of lens power. The ability to correct higher-order aberrations in these materials has broad potential applicability for optimization of vision in patients undergoing cataract and refractive surgery. (+info)
Dynamics of novel feet of Dictyostelium cells during migration.
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We observed the dynamics of actin foci in live Dictyostelium cells expressing GFP-actin. Actin foci were dynamic structures, but they were fixed on the substratum during cell migration. Interference reflection microscopy revealed that the ventral cell membrane was closer to the substratum at sites of actin foci. Furthermore, some actin foci were incorporated into the retraction fibers, ripped off from the cells and eventually shed on the substratum after the cells moved away. The velocity of the cells was inversely proportional to the number of actin foci. Measurement of traction force using a silicone substratum demonstrated that the traction force was transmitted to the substratum through actin foci. Taken together, several lines of evidence strongly suggest that actin foci function as the active 'feet' of Dictyostelium cells. We also found evidence suggesting that changing step is regulated in a coordinated manner during cell migration. Possible mechanisms by which these cells migrate across substrata are discussed in this context. (+info)
Fractal branching pattern of the monopodial canine airway.
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Unlike the human lung, monopodial canine airway branching follows an irregular dichotomized pattern with fractal features. We studied three canine airway molds and found a self-similarity feature from macro- to microscopic scales, which formed a fractal set up to seven scales in the airways. At each fractal scale, lateral branches evenly lined up along an approximately straight main trunk to form three to four two-dimensional structures, and each lateral branch was the monopodial main trunk of the next fractal scale. We defined this pattern as the fractal main lateral-branching pattern, which exhibited similar structures from macro- to microscopic scales, including lobes, sublobes, sub-sublobes, etc. We speculate that it, rather than a mother-daughter pattern, could better describe the actual asymmetrical architecture of the monopodial canine airway. (+info)
Silicone patch saphenoplasty to prevent repeat recurrence after surgery to treat recurrent saphenofemoral incompetence: long-term follow-up study.
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OBJECTIVE: Barrier techniques have been proposed to improve the results of repeat surgery to treat recurrent saphenofemoral junction incompetence. We hypothesized that interposition of a silicone implant would contain postoperative neovascularization and thus reduce the incidence of clinical recurrence at 5-year follow-up. METHODS: We compared the results of repeat interventions with use of silicone sheeting with a control group without artificial implants. The study was performed in hospitalized patients in a level 3 referral center (University Hospital). All patients underwent new flush ligation in the groin, with stab avulsion of recurrent varicosities. Two closure techniques were compared: in group A (33 limbs) the groin incision was closed in two layers; in group B (35 limbs) a piece of silicone sheeting was sutured on the saphenous stump. Clinical examination and duplex scanning were performed after 1 and 5 years postoperatively. Limbs operated on were checked in particular for the presence of recurrent thigh varicose veins. Color-coded duplex scanning was performed to assess for the presence of clinically relevant neovascularization, defined as the presence of a new vein with diameter at least 4 mm and with pathologic reflux in direct connection with incompetent varicose veins at thigh level. RESULTS: Clinical examination after 1 year showed recurrent thigh varicosities in 24% of limbs in group A and 12% of limbs in group B (P =.369). After 5 years recurrent thigh varicosities were observed in 58% of limbs in group A and in 26% of limbs in group B (P =.009). Duplex scans after 1 year revealed neovascularization in 27% of limbs in group A and 6% of limbs in group B (P =.018). After 5 years neovascularization was present in 45% of limbs in group A and 9% of limbs in group B (P =.0007). CONCLUSIONS: The use of a silicone patch at repeat operation to treat recurrent varicose veins caused by new incompetence at the level of the saphenofemoral junction is associated with a lower incidence of recurrent thigh varicosities and neovascularization compared with a control group in which no additional barrier technique was used. (+info)
Clinical evaluation of radiotherapy for advanced esophageal cancer after metallic stent placement.
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AIM: To evaluate the therapeutic effect of radiotherapy for esophageal cancer after expandable metallic stent placement. METHODS: Ten cases of advanced esophageal cancer were evaluated, 7 having complete obstruction and 3 with digestive-respiratory fistula. Ten nitinol stents were placed at the site of stenosis. Patients were treated with a total dose of 1 200 cGy divided into 3 fractions of 400 cGy 4-7 d after stents placement. RESULTS: All the 10 stents were placed successfully at one time. After radiotherapy for advanced esophageal cancer, the survival period of the cases ranged from 14 to 22 mo, with a mean survival of 17 mo. No re-stenosis occurred among all the 10 cases. CONCLUSION: Stent placement combined with radiotherapy for esophageal cancer is helpful to prolong patients' survival and reduce occurrence of re-stenosis. (+info)
Long-term silicone central venous catheters impregnated with minocycline and rifampin decrease rates of catheter-related bloodstream infection in cancer patients: a prospective randomized clinical trial.
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PURPOSE: To evaluate the efficacy of long-term nontunneled silicone catheters impregnated with minocycline and rifampin (M-R) in reducing catheter-related bloodstream infections. PATIENTS AND METHODS: This prospective, randomized, double-blind clinical trial was conducted at M.D. Anderson Cancer Center, a tertiary care hospital in Houston, TX. All patients in the trial had a malignancy. RESULTS: Between September 1999 and May 2002, 356 assessable catheters were used: 182 M-R and 174 nonimpregnated. The patients' characteristics were comparable between the two study groups. The mean (+/- standard deviation) duration of catheterization with M-R catheters was comparable to that of nonimpregnated catheters (66.21 +/- 30.88 v 63.01 +/- 30.80 days). A total of 17 catheter-related bloodstream infections occurred during the course of the study. Three were associated with the use of M-R catheters and 14 were associated with the nonimpregnated catheters, with a rate of catheter-related bloodstream infection of 0.25 and 1.28/1,000 catheter-days, respectively (P = .003). Gram-positive cocci accounted for the majority of the organisms causing the infections. There were no allergic reactions associated with M-R catheters. CONCLUSION: Long-term nontunneled central venous catheters impregnated with minocycline and rifampin are efficacious and safe in reducing catheter-related bloodstream infections in cancer patients. (+info)