Stability of desmopressin loaded in liposomes.

Desmopressin-containing liposome formulations have been developed for intranasal administration previously. Positively charged liposomes were found to be an efficient delivery system for desmopressin. In this study, stability of the loaded desmopressin in positively charged liposomes was further investigated. Comparison of the stability of desmopressin in solution and liposomes was made. Degradation of desmopressin was shown to follow a pseudo-first-order reaction. Degradation of desmopressin in both solution and liposomes demonstrated the same kinetic behavior and exhibited no significant difference in half-lives. Similar v-shape pH-rate profile was found for desmopressin degradation in solution and liposomes. At pH 4.0, the inflection point of the v-shape pH-rate curve, the reaction rate of desmopressin was lowest and the stability was greatest. The stability of lipid ingredients of dioleoylphosphatidylcholine (DOPC), cholesterol (C), and stearylamine (S) in the liposome dispersion at pH 4.0 was studied. Results demonstrated that DOPC, C, and S were relatively stable in the liposome structure when formulated with desmopressin. The degradation of desmopressin in solution and liposomes in the presence of alpha-chymotrypsin was investigated. A longer half-life for desmopressin in liposomes than in solution was observed. It was suggested that desmopressin was protected by the liposomes against alpha-chymotrypsin digestion.

Development of a real-time control strategy with artificial neural network for automatic control of a continuous-flow sequencing batch reactor.

The purpose of this study is to develop a reliable and effective real-time control strategy by integrating artificial neural network (ANN) process models to perform automatic operation of a dynamic continuous-flow SBR system. The ANN process models, including ORP/pH simulation models and water quality ([NH4(+)-N] and [NOx(-)-N]) prediction models, can assist in real-time searching the ORP and pH control points and evaluating the operation performances of aerobic nitrification and anoxic denitrification operation phases. Since the major biological nitrogen removal mechanisms were controlled at nitrification (NH4(+)-N-->NO2(-)-N) and denitritification (NO2(-)-N-->N2) stages, as well as the phosphorus uptake and release could be completely controlled during aerobic and anoxic operation phases, the system operation performances under this ANN real-time control system revealed that both the aeration time and overall hydraulic retention time could be shortened to about 1.9-2.5 and 4.8-6.2 hrs/cycle respectively. The removal efficiencies of COD, ammonia nitrogen, total nitrogen, and phosphate were 98%, 98%, 97%, and 84% respectively, which were more effective and efficient than under conventional fixed-time control approach.

Characterization of calcitonin-containing liposome formulations for intranasal delivery.

Calcitonin-containing liposome formulations were characterized to obtain information for evaluation of their feasibility in intranasal delivery. The parameters of liposomal charge characteristics, charge inducing agent concentration, calcitonin concentration and pH of the medium on the loading efficiency and leakage behaviour, and the chemical stability of calcitonin in liposomes were investigated. Results showed that the loading efficiency of calcitonin increased with increasing the added concentration of calcitonin. The magnitude of the loading efficiency due to the liposomal charge of negative, positive and neutral characteristics was in the order of negatively charged liposome > neutral liposome > positively charge liposome. The increase of molar ratio of phosphatidylserine in liposomes showed an increase of loading efficiency; while, the increase of molar ratios of stearylamine showed a decrease of loading efficiency. The loading efficiency at pH 7.4 was greater than that at pH 4.3. The leakage of positively charged liposomes was greater than that of neutral and negatively charged liposomes. The leakage at pH 4.3 was faster than that at pH 7.4. The leakage of positively charged liposomes increased as temperature increased. The chemical stability of calcitonin in both solution and liposomes demonstrated a pseudo-first-order kinetic degradation. Less degradation was observed at pH 3.4 and 4 degrees C. The degradation rate of calcitonin in solution, or in positively charged, negatively charged, and neutral liposomes, exhibited no significant difference. The particle size of the calcitonin-containing liposomes after storage for 1 month at pH 4.3 and 4 degrees C showed little change.

Preparation of desmopressin-containing liposomes for intranasal delivery.

The loading and leakage characteristics of the desmopressin-containing liposomes and the effect of liposomes on the nasal mucosa permeation and antidiuresis of desmopressin were investigated. Higher loading efficiency of desmopressin for positively charged liposomes than negatively charged liposomes was obtained, and neutral liposomes resulted in a similar loading efficiency as that of positively charged liposomes. Greater leakage of desmopressin from negatively charged liposomes than from positively charged and neutral liposomes was shown. The increase of permeability of desmopressin through the nasal mucosa indicated positively charged liposomes>negatively charged liposomes>solution. It was suggested that the enhanced contact time of positively charged liposomes with negatively charged nasal mucosa led to a high local desmopressin concentration on the penetration site to promote an effective penetration of desmopressin through the nasal mucosa. The desmopressin antidiuresis result after intranasal administration was in good agreement with the permeability result in the order of positively charged liposomes>negatively charged liposomes>solution. One of the mechanisms for the explanation of the best result on the enhancement of antidiuresis for positively charged liposomes may be the bioadhesive effect of the liposomes on the negatively charged nasal mucosa.

Enhancement of nasal absorption of calcitonin loaded in liposomes.

Intranasal administration of calcitonin-containing liposomes in rabbits was investigated to evaluate the in vivo calcitonin absorption performance. Plasma calcitonin concentrations and calcium levels were measured and pharmacokinetic parameters were calculated. The bioavailability of calcitonin resulted from the intranasal delivery formulations demonstrated an order of calcitonin-containing positively charged liposomes > calcitonin-containing negatively charged liposomes > calcitonin solution. The significant enhancement of bioavailability of calcitonin for positively charged liposomes may be due to the charge interaction of positively charged liposomes with the negatively charged mucosa surface. Marked accumulation of positively charged liposomes was found on the negatively charged nasal mucosa surface. The retention of positively charged liposomes on the nasal mucosa resulted in an increase of residence time with high local concentration of calcitonin for increase of absorption.

An evaluation of preoperative ibuprofen for treatment of pain associated with orthodontic separator placement.

Patients undergoing orthodontic treatment can experience significant levels of pain. This study assessed the effectiveness of preoperative ibuprofen in reducing the incidence and the severity of pain after orthodontic separator placement. Sixty-three adolescent patients (mean age, 13 years) were included in this randomized, double-blind, placebo-controlled, prospective study. Patients were randomly assigned to 1 of 3 experimental conditions: (1) 400 mg of ibuprofen taken orally 1 hour before separator placement and a lactose placebo taken orally immediately after the appointment, (2) a lactose placebo taken orally 1 hour before separator placement and 400 mg of ibuprofen taken orally immediately after the appointment, or (3) a lactose placebo taken orally 1 hour before separator placement and again immediately after the appointment. The patient's level of discomfort was assessed with a visual analog scale at 2, 6, and 24 hours, as well as at 2, 3, and 7 days after placement of the orthodontic separators. An analysis of variance and Duncan's multiple range test revealed that 2 hours after their orthodontic appointment the patients who had taken ibuprofen 1 hour before separator placement had significantly less pain with chewing than did the patients who received either ibuprofen postoperatively or a placebo. Additional measures suggest a trend for less pain for this group of patients. These results support the use of pretreatment ibuprofen for patients requiring analgesics for orthodontic discomfort. Future study of the use of preemptive analgesics in orthodontics is warranted.

Acyclovir-containing liposomes for potential ocular delivery. Corneal penetration and absorption.

The in vitro corneal penetration and in vivo corneal absorption of acyclovir from an acyclovir-containing liposome system were investigated. Results of in vitro corneal penetration demonstrated that positively charged liposomes resulted in a penetration rate lower than those of negatively charged liposomes and free acyclovir in solution. An in vivo study indicated that the extent of acyclovir absorption from positively charged liposomes was higher that those from negatively charged liposomes and free acyclovir. The acyclovir concentration in the cornea after administration of positively charged liposomes showed that an acyclovir deposition in the cornea was greater than those of negatively charged liposomes and free acyclovir. From morphological observation of the cornea surface treated with liposomes, it was suggested that positively charged liposomes formed a completely coated layer on the cornea surface. These liposomes would bind intimately on the cornea surface, leading to an increase of residence time. Therefore, positively charged liposomes resulted in an increase of acyclovir (ACV) absorption.

Adsorption of calcitonin to glass.

Surface adsorption of calcitonin on soda lime silica glass was investigated. An attempt was also made to examine the effect of additives on the inhibition of calcitonin adsorption. Results showed that the adsorption isotherms were of the Langmuir and Freundlich type, depending on pH. Less adsorption was found for calcitonin at pH 4.3. The addition of nonionic surfactants such as Pluronic F68 and Tween 80 to the calcitonin solutions demonstrated inhibition of absorption and reduction of adsorption rate. The addition of chlorobutanol also showed the effect of minimizing adsorption.

In vitro gene transfer in mammalian cells via a new cationic liposome formulation.

A new cationic liposome formulation of sphingosine (SP) and dioleoylphosphatidylethanolamine (DOPE) was developed as an efficient transfection reagent. This SP/DOPE liposome showed efficient transfection in a wide variety of mammalian cancer cells. No significant cytotoxicity of the SP/DOPE liposome to cells was observed. The tranfection activity was greater than that of a well-reported liposome which was made from a cholesterol derivative 3beta-[N-(N',N'-dimethylaminoethane)-carbamoyl] cholesterol (DC-Chol) and the neutral lipid DOPE. In addition, the SP/DOPE liposome was found to be less toxic to cells than the DC-Chol/DOPE liposome. Stable transfections mediated by SP/ DOPE liposome were also demonstrated. These results suggest that the SP/DOPE liposome may provide a good gene delivery system to be used in the human cancer gene therapy.

The N-terminal 178-amino-acid domain only of the SV40 large T antigen acts as a transforming suppressor of the HER-2/neu oncogene.

The deregulation of the HER-2/neu protooncogene was demonstrated in a wide variety of human cancers and shown to be correlated with the progress of malignancy and metastasis in animal models. Repression of HER-2/neu overexpression suppressed the malignant phenotypes of HER-2/neu-overexpressing cancer cells. This suggested that HER-2/neu may be a good target for developing anti-cancer drugs. We found a deletion mutant of simian virus 40 (SV40) large T antigen (LT) suppresses the HER-2/neu oncogene expression at the transcriptional level. PCR clones of this mutant SV40LT, named LT425, which contains the N-terminal region of amino acid residues 1-178 of SV40LT, were subcloned and stably transfected into the HER-2/neu-overexpressing human ovarian cancer SKOV3.ip1 cells. These LT425 clones were found to be able to down-regulate the endogenous production of p185(HER-2/neu). In addition, the LT425-expressing stable transfectants showed reduced growth rate, low soft agarose colony forming ability, and low tumorigenic potential as compared with the parental line. These data suggested that the N-terminal 178 amino acids domain only of SV40LT may act as a transforming repressor of HER-2/neu oncogene.

Free sphingosines in oral epithelium.

Free sphinogosines, intermediates in the biosynthesis of ceramides and inhibitors of protein kinase C, have been found to be present in significant concentrations in epidermis and oral epithelia of the pig (Sus scrofa). Concentrations of sphingosines were higher in the outer portion of epidermis (4.4 mg/g), palatal epithelium (3.9 mg/g) and buccal epithelium (0.7 mg/g) compared to the inner portion of the epithelia (1.0, 0.9 and 0.4 mg/g, respectively). Free sphingosines may provide antimicrobial activity at the epithelial surfaces, and the sphingosine gradient may modulate epithelial differentiation.

Inhibition of microtubule assembly is a possible mechanism of action of mitoxantrone.

We have found that mitoxantrone can inhibit the polymerization of brain tubulin in a dose dependent manner. MXT had relatively high affinity for tubulin but had no appreciable effect on tubulin associated guanosine-triphosphatase (GTPase) activity nor could it compete with vinblastine (VB) and colchicine (Col) for tubulin binding sites. Furthermore, MXT (0.1-10 microM) is antiproliferative to cold-treated (0 degree C) epithelial cells after only brief exposure (30 min). These results indicated that MXT is a microtubule inhibitory agent and can exert its anticellular effect through modulation of microtubule assembly.

Effect of stabilization temperature on the degradation of adriamycin in albumin microspheres.

The effect of stabilization temperature on the degradation of adriamycin HCl during the preparation of albumin microspheres was investigated. The degradation of adriamycin HCl by heating at various temperature with different time interval in dried adriamycin HCl powder, adriamycin HCl aqueous solution, wetted Adriablastina (adriamycin HCl with lactose) powder and Adriablastina aqueous solution was also studied. In the presence of water the degradation of adriamycin HCl was found; whereas, in the absence of water no degradation occurred. The degradation of adriamycin HCl in solution and wetted powder showed a zero order reaction. An increase in temperature increased degradation rate. The rate constant for adriamycin HCl degradation in Adriablastina solution obtained was in good agreement with that in adriamycin HCl solution. It was suggested that the presence of lactose had no interference in the degradation of adriamycin HCl. The zero-order reaction of degradation was attributed to the drug behaved like a suspension. The degradation of adriamycin HCl at various stabilization temperature during the preparation of microspheres had the same tendency as those of the adriamycin HCl solution and the wetted adriamycin HCl powder that were heated by the DSC instrument with the condition similar to the preparation of microspheres.

Field and laboratory determination of a poly(vinyl/vinylidene chloride) additive in brick mortar.

A polymerized vinyl/vinylidene chloride additive, used in brick mortar during the 60s and 70s, is detected at the building site by the field method, which employs a commercially available chloride test strip. The field test results can then be verified by the laboratory methods. In one method, total chlorine in the mortar is determined by an oxygen-bomb method and the additive chloride is determined by difference after water-soluble chlorides have been determined on a separate sample. In the second method, the polymerized additive is extracted directly from the mortar with tetrahydrofuran (THF). The difference in weight before and after extraction of the additive gives the weight of additive in the mortar. Evaporation of the THF from the extract leaves a thin film of the polymer, which gives an infrared "fingerprint" spectrum characteristic of the additive polymer.

Effect of liposomes on suspension stability.

The effect of positively charged liposomes on the stability of negatively charged indomethacin particle suspensions was investigated by adsorption, microelectrophoresis, sedimentation volume, and redispersibility. It was found that flocculation occurred in the neighborhood of the zero point of charge of the liposome:indomethacin suspensions. This resulted from the operation of van der Waals attraction under the condition of nil electrostatic repulsion. Correlation among the results of adsorption, microelectrophoresis, sedimentation volume, and redispersibility was good. The mixing effect of the suspension was examined by microelectrophoresis and confirmed by sedimentation volume and redispersibility. Results indicate that there was no difference between the method of dilution of the liposome:indomethacin concentrated suspension after mixing and the method of dilution of liposomes prior to mixing with the indomethacin suspension. This was due to interaction depending on the charge density of the particles.

Sedimentation volume, redispersibility and appearance of a polystyrene latex suspension in the presence of nonionic surface active agents.

The sedimentation volume, redispersibility and appearance of a polystyrene latex suspension in the presence of nonionic surface active agent of polyoxyethylene glycol monoethers of n-hexadecanol have been investigated. At low concentrations of nonionic surface agents, hard caked suspensions were found. This is probably due to the attraction between the uncoated areas or the mutual adsorption of the adsorbed molecules on the bare surface of the particles in the sediment. At high concentrations of nonionic surface active agents, the redispersibility of the particles was affected by the steric repulsive force.

Technetium 99m-DTPA microcapsules: a new preparation for gastric emptying studies.

Technetium 99m-DTPA microcapsules have been developed to measure gastric emptying. Such capsules not only provide high labeling efficiency in vitro, but demonstrate limited dissociation in vivo, resulting in decreased error during measurement. In normal control subjects, the half-life ranged from 40 to 80 minutes under the aforementioned conditions.

The effect of xanthine derivatives on red blood cells: microelectrophoretic studies.

The effect of xanthine derivatives on the variation of surface charges of red blood cells has been investigated. Results of mobility curves showed that the derivatives increase the surface charges on the cells, whereas there is little effect on the surface charges of liposomes.

Methyl mercury and inorganic mercury collection by a selective chelating resin.

A commercially available chelating resin selectively and quantitatively collects methyl mercuric and inorganic mercuric forms of mercury to the exclusion of all other metals studied, except the noble metals. Both forms of mercury can be collected from pH 1 to 9. Collected mercury is readily eluted with a slightly acid, 5 percent solution of thiourea, and the resin can be reused for many cycles. Selectivity, pH effects, capacity, and elution characteristics of the resin are described. A resin-loaded paper composed of 50 percent resin and 50 percent cellulose shows properties similar to those of the loose resin.