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Development of a sustained-release biodegradable polymer delivery system for site-specific delivery of oligonucleotides: characterization of P(LA-GA) copolymer microspheres in vitro.

Development of a Sustained-Release Biodegradable Polymer Delivery System for Site-Specific Delivery of Oligonucleotides: Characterization of P(LA-GA) Copolymer Microspheres In Vitro Antisense oligodeoxynucleotides (ODNs) can selectively inhibit individual gene expression provided they gain access to and remain stable at the target site for a sufficient period of time. Biodegradable sustained-release delivery systems may facilitate site-specific delivery and also prevent degradation of ODNs by nucleases whilst delivering the nucleic acid in a controlled manner to the desired site of action. In this study, we have characterized biodegradable poly (lactide-co-glycolide) (P(LA-GA)) 50:50 microspheres for the potential delivery of antisense oligonucleotides in vivo. Phosphodiester (PO) oligonucleotides complementary to either c-myc proto-oncogene or the tat gene in HIV-RNA were adequately incorporated within P(LA-GA) microspheres with entrapment efficiencies up to 60% depending on particles size. In vitro release profiles of antisense nucleic acids from 10-20 microm size microspheres over 56 days in physiological buffer were triphasic. Profiles were characterised by an initial burst effect during the first 48 hours (phase 1) of release followed by a more sustained release (phase 2) with an additional increased release (phase 3) being observed after 25 days which corresponded with bulk degradation of the copolymer matrix. The release profiles were influenced by microsphere size, copolymer molecular weight, ODN loading, ODN length and by the pH of release medium used. The serum stability of PO ODNs was significantly improved when entrapped within P(LA-GA) microspheres and the hybridization capability, as assessed by duplex melting (Tm) measurements, of released ODN was not impaired by the double-emulsion microsphere fabrication procedure used. Thus, P(LA-GA) microspheres appear to be promising candidates for improving site-specific delivery profiles for ODNs and are worthy of further evaluation in vivo.

Base Sequence↗

Development and evaluation of sustained release mini-matrices prepared via hot melt extrusion.

Sustained release mini-matrices (multiple unit dosage form) were developed by means of hot-melt extrusion using ibuprofen as the model drug and ethyl cellulose as sustained release agent. Ibuprofen release from the ibuprofen-ethyl cellulose matrices (60:40 w/w) was too slow (20% in 24 h). Other excipientia (hydroxypropyl methylcellulose and xanthan gum) were added to the formulation to increase the drug release. Changing the viscosity and substitution type of HPMC, the amount of HPMC, the drug load and the HPMC:EC ratio modified the in vitro drug release. Burst release was noticed for the formulations containing HPMC and a nearly time independent drug release was seen for the xanthan gum based mini-matrices. Drug release from the mini-matrices was mainly diffusion controlled and swelling played an important role to obtain complete drug release. The formulations were at least 12 months stable during storage at 60% RH and room temperature. At a higher relative humidity and temperature the drug release increased.

Delayed-Action Preparations↗

Discovering older women's experience of urinary incontinence.

Grounded theory was used to acquire an understanding of older women's experience of urinary incontinence (UI). Women explained that accidents or other problems related to the UI were threats to their self-esteem. These threats provided strong incentives to develop an effective continence care system which would help to protect their self-esteem. If they were successful in developing an effective system, it was possible that they could accept the UI and lead "normal" lives. Examination of the data using the constant comparative method revealed the self-care system that the women in this study produced to manage the UI, but not how they developed or sustained it. Further investigation into how women with UI develop and sustain continence care routines is needed, so that nurses can provide better assessments and nursing care.

Adaptation, Psychological↗

Towards a sustainable livestock production in developing countries and the importance of animal health strategy therein.

Livestock and animal health development projects have not always led to substantial increases in animal productivity or in farmers' welfare. Some have even resulted in unsustainable systems, when they were not based on an understanding of (livestock) production systems. The multipurpose functions of livestock and complex relationships between the biological, technical and social components require a systems approach, whereby nutrition, animal health, breeding, biotechnology knowhow, inputs and technologies are used to optimise resource use. The challenge for developed and developing countries is to reverse the current degradation of the environment, and arrive at sustainable increases in crop and livestock production to secure present and future food supplies. For rural development, governments should show long term commitment and political will to support the rural population in development programmes, because smallholders (including women and landless livestock keepers) represent a large labour force in developing countries. Different systems need different approaches. Pastoral systems must focus on effective management of grazing pressure of the rangelands. Communal rangelands management involves not only the development and application of technologies (e.g. feedlots, vaccination campaigns), but also land tenure policies, institutional development, economic return and a reduction in the number of people depending upon livestock. Smallholder mixed farms must aim at intensification of the total production system, in which external inputs are indispensable, but with the emphasis on optimum input-output relationships by reducing resource losses due to poor management. Resource-poor farming systems must aim at the improved management of the various livestock species in backyards and very small farms, and proper packages for cattle, buffaloes, sheep, goats, rabbits and poultry should be developed. Specialised commercial livestock farming systems (poultry, pigs, dairy or meat) can only be sustainable with adequate marketing, supply of quality feed, veterinary services, labour, management and control of pollution. Animal health programmes play a keyrole in the proposed system approach.

Agriculture↗

Does thyroid function in developing birds adapt to sustained ammonium perchlorate exposure?

The effects of a wide range of ammonium perchlorate (AP) concentrations in drinking water on thyroid function in bobwhite quail chicks was investigated at 2, 4, and 8 weeks of exposure. We measured plasma thyroid hormones (THs) to evaluate organismal thyroid status, thyroid weights to evaluate hypothalamic-pituitary-thyroid (HPT) axis activation, and thyroidal TH content to assess TH stores. At the highest AP exposures plasma THs were decreased, thyroid glands were hypertrophied, and thyroidal TH content was decreased. As in our previous studies, thyroidal thyroxine (T(4)) content was the most sensitive indicator of decreased thyroid function; plasma T(4) and thyroid weight were much less sensitive. The lack of sensitivity of these variables appears to result from cyclic patterns of thyroid responses involving the HPT axis and intermittent release of stored THs from the thyroid gland. With sustained AP exposure (8 weeks), at the lowest range of AP concentrations used, chicks showed adaptation in thyroid function that fully compensated for the initial (2 week) effects of AP. At the intermediate AP concentrations there was partial compensation for the initial AP effects. At the highest AP exposures used, thyroid function was very low throughout the study, with no indication of compensatory responses. The capability of chicks to increase some aspects of their thyroid function adaptively in response to some levels of sustained AP exposure is contrary to the common generalization that developing animals are most vulnerable to environmental contaminants.

Adaptation, Physiological↗

Development of a model for sustainable delivery of outreach allied health services to remote north-west Queensland, Australia.

INTRODUCTION: Development of sustainable multidisciplinary services in north-west Queensland, Australia, is challenged by large distances, culturally diverse communities, a prolonged wet season, a history of poor retention of allied health professionals (AHPs), and high prevalence of chronic disease. In 2001, the Northern Queensland Rural Division of General Practice drew on wide community consultation and recent research into the recruitment and retention of AHPs to develop a Model for delivery of outreach allied health services operating within a primary healthcare framework. AIM: to develop a Model of allied health service delivery using the principles of primary healthcare, to meet the needs of 11 culturally diverse (indigenous, non-indigenous and mixed) remote communities, in an area of over 373 000 km2. METHODS: The development of the outreach Model of allied-health service delivery occurred over four stages: (1) Formulation of a planning matrix as the outcome of a workshop to identify the core components; (2) Environmental scan including mapping of existing allied health services and identification of gaps in service delivery; community consultation to assist in the gap analysis of service delivery, identification health priorities at a local level, and provision of context as to how services should be provided; analysis of available morbidity, mortality data and screening data; (3) Desktop analysis of previous research into the recruitment and retention of allied health professionals, and determination of a 'reasonable' level of service delivery in rural and remote areas; and (4) Synthesis of information to develop options or a Model of service delivery. RESULTS: The environmental scan indicated the need for a raft of AHPs to address chronic disease and injury in the target communities, including the disciplines of physiotherapy, podiatry, dietetics, occupational therapy, speech pathology and psychology. The Model of service delivery sought to provide services in a form appropriate to communities (ie regular and reliable), with duration of visit providing opportunities for case conferencing and inservice education with resident health professionals and workers. A range of strategies were developed to support the recruitment and retention of allied health professionals, including working and travelling in functional teams; orientation to remote practice; schedules that recognize the need for time back at base, and utilisation of aircraft to minimise travel time; employment packages recognizing isolated and remote practice, professional development, postgraduate study, professional and clinical mentoring; financial subsidies for housing and childcare. A hub-and-spoke model of service delivery was developed with functional teams visiting each community on a 6-weekly rotation for 2-3 days/community per rotation, dependent on population. The duration of visit would promote opportunities for community development, training therapy assistants to promote continuity of care, and health promotion activities within the primary healthcare framework under which the service would operate. Integration and coordination with existing resident health and community services, and visiting services, was considered through the development of a 6 month calendar of service delivery, and Memoranda of Understanding with state health services to allow access to clinics and client records. CONCLUSION: The planning matrix informed and underpinned the final form of the outreach Model of service delivery. The process described enabled the development of a Model for delivering allied health services in a remote rural area that considered the burden of disease, context for service delivery addressing community concerns with visiting services, recruitment and retention of health professionals and integration with resident and visiting health and community services. The strategies employed provide a template for allied health service development in rural and remote areas internationally.

Journal Article↗

Continent small-intestine reservoir construction: a tapered intussusceptum promotes sustained continence.

Developed for the study of dialysis in the continent jejunal reservoir (CJR), a novel, uncomplicated approach to achieve continence in construction of a small-bowel reservoir is presented. We utilize a technique of constructing a continent nipple valve, which entails the reduction or tapering of the intussusceptum prior to invagination into the reservoir. We have thus far performed the procedure successfully in 21 dogs. All animals have achieved absolute continence. Complications have occurred in two animals, neither complication involving the nipple valve. Pressure-volume cytometry in nine animals demonstrates continence in the awake animal at pressures of up to 40 cm H2O (volumes being limited by animal discomfort due to reservoir distention). In postmortem studies, reservoir capacities of > 1000 ml and pressures of > 70 cm H2O have been attained without loss of continence or prolapse of the nipple valve. Continence is sustained even when the reservoir and nipple valve are subjected to high intraluminal pressures. Incorporating a tapered intussusceptum, the continent reservoir provides absolute continence without the use of cumbersome mesh fixation or lithotropic intraluminal staples.

Animals↗

Sustainable sludge management in developing countries.

Worldwide, unsanitary conditions are responsible for more than three million deaths annually. One of the reasons is the low level of sanitation in developing countries. Particularly, sludge from these regions has a high parasite concentration and low heavy metal content even though the available information is limited. Different issues needed to achieve a sustainable sludge management in developing nations are analysed. Based on this analysis some conclusions arise: sludge management plays an important role in sanitation programs by helping reduce health problems and associated risks; investments in sanitation should consider sludge management within the overall projects; the main restriction for reusing sludge is the high microbial concentration, which requires a science-based decision on the treatment process, while heavy metals are generally low; adequate sludge management needs the commitment of those sectors involved in the development and enforcement of the regulations as well as those that are directly related to its generation, treatment, reuse or disposal; current regulations have followed different approaches, based mainly on local conditions, but they favour sludge reuse to fight problems like soil degradation, reduced crop production, and the increased use of inorganic fertilizers. This paper summarises an overview of these issues.

Biodegradation, Environmental↗

[Surgery in pheochromocytoma. 12-year development].

Hypertension (sustained and/or paroxysmal) is the most common symptom of pheochromocytoma. Correct evaluation nearly always leads to the diagnosis, and complete surgical excision is the definitive treatment. Our study deals with preoperative evaluation, operative morbidity and long-term results after surgery. During the 12-year period (1981-1992) 31 patients (48 years, 25-85) with pheochromocytoma were treated at our institution. The selected preoperative management was reviewed on the basis of patient records. Long-term follow-up was carried out consecutively and personally. All patients received alpha-adrenergic blockers to achieve preoperative normotension and volume repletion. All resections were performed by laparotomy; two of the early cases were extended into the chest. 27 of 29 patients (93.1%) had elevated levels of urinary vanillylmandelic acid; a similar sensitivity was noted in the urinary catecholamines (24/26 = 92.3%). In anatomical localization CT-scan was accurate in 100% (27/27). MIGB scintigraphy was of help in 21 of 23 (91.3%) and, in the most recent patients, MRI was helpful in 3 of 3 (100%). No patient died during the first 30 days after surgery. One patient developed an anaphylactic reaction after cephalosporin administration (morbidity: 3.2%). 2 patients (6.4%) with malignant pheochromocytoma developed a recurrent tumor during the follow-up period. Resection of pheochromocytomas by laparotomy has a low perioperative morbidity and mortality after standardized preparation. A positive MIBG scintigraphy allows extra-adrenal localization. Better resolution and multiplanar imaging are the advantages of MRI. Perioperative management and new imaging techniques--eliminating arteriography and venous sampling among others--have simplified surgical treatment and improved its safety.

Adrenal Gland Neoplasms↗

Development of novel sustained-release system, disintegration-controlled matrix tablet (DCMT) with solid dispersion granules of nilvadipine (II): in vivo evaluation.

A novel sustained-release (SR) system, disintegration-controlled matrix tablet (DCMT), was developed for poorly water-soluble drugs. DCMT, consisting of wax and solid dispersion (SD) granules containing a disintegrant, could control the release of nilvadipine (NiD), a model compound, by its disintegration. In the present study, two DCMTs (DCMT-1 and DCMT-2) with different release rates of NiD were orally administered to beagle dogs, and in vivo absorption of NiD from DCMTs was compared with that from immediate-release (IR) tablets. DCMTs successfully sustained the absorption of NiD longer than IR tablets, while they did not decrease the bioavailability of NiD. DCMT-2, providing the slower release of NiD than DCMT-1, prolonged the absorption longer than DCMT-1. In vivo absorption profiles of NiD from DCMTs were significantly correlated with in vitro release profiles, suggesting that the release property from DCMTs would maintain regardless of the change in physiological condition through the gastrointestinal tract. Furthermore, the food intake did not affect the absorption of NiD after oral administration of DCMT-2. The present results strongly indicate that the DCMT system would be a promising SR system, which could improve the solubility and sustain the absorption of poorly water-soluble drugs.

Administration, Oral↗

Clobazam in long-term epilepsy treatment: sustained responders versus those developing tolerance.

Clobazam (CLB) is a structurally unique benzodiazepine (BZD) that has anticonvulsant activity in all types of refractory seizures. The main drawback to CLB, as to other BZDs, is the occurrence of tolerance. To date, there has been no way to predict which patients will develop tolerance. We compared clinical features and treatment variables between two groups of patients whose seizures were initially well controlled with CLB: patients with a sustained response and patients who developed tolerance. We retrospectively identified a group of 50 very good responders from among 173 consecutive patients with uncontrolled epilepsy treated with CLB. Very good responders were defined as patients with > 75% reduction in seizures after the addition of CLB who continued CLB treatment for at least 1 month. At a mean follow-up of 37.5 +/- 12.8 months, 25 patients continued to respond and 25 developed tolerance (mean follow-up 17.0 +/- 15.7 months). Tolerance was defined as a relapse to a level > or = 50% of pre-CLB seizure frequency after an initial very good response for a minimum period of 1 month, despite constant CLB dose and, when available, serum levels. There was no change in concomitant medication. Significant differences were noted between the two groups. The sustained response group had a shorter duration of epilepsy (mean 16.5 vs. 24.5 years, p = 0.015), a greater proportion of individuals with a known etiology for their epilepsy (48 vs. 16%, p = 0.006), and higher CLB levels (0.50 vs. 0.22 microM, p = 0.017), but no significant difference in N-desmethyl-CLB levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

High-dose epinephrine improves the return of spontaneous circulation rates in human victims of cardiac arrest.

STUDY OBJECTIVES: To evaluate the return of spontaneous circulation (RSC) rates in human victims of cardiac arrest treated with standard doses of epinephrine (SDE) or high-dose epinephrine (HDE). DESIGN: Prospective case series. SETTING: A university hospital emergency department during 1987 through 1989. PARTICIPANTS: Forty-nine adult victims of nontraumatic cardiac arrest. INTERVENTIONS: At the discretion of the treating physician, patients received epinephrine in bolus doses ranging from 1 to 15 mg. HDE was defined as a dose of at least 0.2 mg/kg; smaller doses were defined as SDE. Patients were grouped as +RSC if they developed a sustained spontaneous palpable pulse or blood pressure and as -RSC if they did not develop a pulse or blood pressure. MEASUREMENTS: Patients were grouped as +RSC if they developed a sustained spontaneous palpable pulse or blood pressure and as -RSC if they did not develop a pulse or blood pressure. Patients were also grouped by their presenting rhythm. Potentially perfusing rhythm was electromechanical dissociation or ventricular tachycardia. Nonperfusing rhythm was asystole or ventricular fibrillation. Rates were analyzed using the Fisher exact test and the two-tailed unpaired t test. HDE improved the rate of initial resuscitation (P = .008). The effect was greatest in patients with nonperfusing rhythms (P = .014) and disappeared when evaluating patients with potentially perfusing rhythms. No patient survived to hospital discharge. CONCLUSION: High-dose epinephrine improves initial resuscitation rates in human victims of cardiac arrest. Its greatest effect is in patients with a nonperfusing rhythm.

Aged↗

Development of a novel sustained release formulation of recombinant human growth hormone using sodium hyaluronate microparticles.

A novel sustained release formulation of recombinant human growth hormone (SR-rhGH) was developed as a once-a-week injection formulation using sodium hyaluronate. SR-rhGH was produced in the form of solid microparticles by spray drying technology. A single administration of a prototype formulation of SR-rhGH with a ratio of hGH:HA=1:1 to cynomolgus monkeys through a fine 26-gauge needle induced continuous elevation of serum IGF-I level for 6 days demonstrating the bioactivity of hGH released from the prototype formulation. For expanded pre-clinical and clinical developments, a pilot-scale process under aseptic condition was established and used for the preparation of the optimized formulation of SR-rhGH with a ratio of hGH:HA=1:3. When the ratio of hGH to HA changed from 1:1 to 1:3, hGH released more slowly in vitro from SR-rhGH with almost complete release of hGH loaded. According to pharmacokinetic and pharmacodynamic studies in beagle dogs, sustained release of hGH from the optimized formulation of SR-rhGH continued for a more extended period longer than 72 h with a lower C(max) than those of prototype formulations. The single administration resulted in an elevation of serum insulin-like growth factor-I (IGF-I) level for 6 days with a maximum value higher than the baseline level by ca. 350 ng/mL, which supported the possibility of SR-rhGH as a once-a-week injection formulation of hGH. The bioavailability of both formulations was comparable to that of hGH daily injection formulation. Finally, toxicity studies revealed no evidence of adverse effect in both cynomolgus monkeys and beagle dogs.

Animals↗

Development of a system of indicators for sustainable port management.

The 1998 project ECOPORT, "Towards A Sustainable Transport Network", developed by the Valencia Port Authority (VPA), established the bases for implementing an Environmental Management System (EMS) in industrial harbours. The use of data and information shall always be required to develop an efficient EMS. The objective of the present research (INDAPORT) study is to propose a system of sustainable environmental management indicators to be used by any port authorities. All activities performed within a port area are analysed for any potential environmental impacts and risks. An environmental analysis of port activities has been carried out with the objective of designing the indicators system. Twenty-one corresponding activities have been identified for large industrial ports. Subsequently, the same methodology developed to date will be later applied to other Spanish and European ports. The study has been developed by using an original system and a methodology, which simultaneously use stage diagrams and systemic models (material and energy flow charts). Multi-criteria analysis techniques were used to evaluate potential impacts (identification of factors and evaluation of impacts).

Decision Support Techniques↗

[Development of gentamicin sulfate sustained release tablet remaining-floating in stomach].

Gentamicin sulfate sustained-release tablet remaining-floating in stomach (G-HBS) was developed based on the hydrodynamically balanced system. The dissolution rate of G-HBS was determined by rotary basket method (100 r/min, 37 +/- 0.5 degrees C, 0.1 mol/L HCl). The release characteristics of G-HBS showed basically first order kinetics with the dissolution rate constant (Kr) of 0.3992 h-1. The mean dissolution time (MDT) of G-HBS was 2.53 h-1. The density of G-HBS was found to have no significant influence on dissolution of G-BHS. The gamma-scintiphoto technique was used to examine the gastric retention time of G-HBS and GCT (gentamicin sulfate conventional tablet). It was shown that the gastric retention time of all subjects taking G-HBS under fed and fasted conditions were all over 4 h, in contrast with GCT, only 1-2 h. The stability of G-HBS was investigated and a tentative two-year expiration date was established. Spectrophotometry for the determination of gentamicin was established. The effect of G-HBS on Campylobacter pyloridis-associated chronic gastritis was examined through clinical trials.

Adult↗

Subconjunctival sustained release 5-fluorouracil.

The authors have developed a sustained release device for 5-fluorouracil (5-FU) made up of a 12 mg pellet of drug coated in a mixture of permeable and impermeable polymers. When implanted subconjunctivally in rabbits, these devices released 5-FU at approximately 1 mg/d for over 10 days. Devices were implanted into four cynomolgus monkey eyes after posterior lip sclerotomy. One eye (treatment) received a device that contained 12 mg 5-FU and the other eye (control) received a placebo device that contained no drug. In control eyes, intraocular pressures returned to normal within 1 wk. In treatment eyes, pressures remained significantly lower throughout the experimental period (3 mo). There was no indication of impaired wound healing, corneal toxicity, inflammation, or damage to the ciliary body in rabbits or monkeys.

Animals↗

Non-aqueous encapsulation of excipient-stabilized spray-freeze dried BSA into poly(lactide-co-glycolide) microspheres results in release of native protein.

Encapsulation of the model protein bovine serum albumin (BSA) into poly(D,L lactide-co-glycolide) (PLG) microspheres was performed by a non-aqueous oil-in-oil (o/o) methodology. Powder formulations of BSA obtained by spray-freeze drying were first suspended in methylene chloride containing PLG followed by coacervation by adding silicon oil and microsphere hardening in heptane. The secondary structure of BSA was determined at relevant steps of the encapsulation procedure by employing Fourier-transform infrared (FTIR) spectroscopy. This fast and non-invasive method demonstrated the potential to rapidly screen pharmaceutically relevant protein delivery systems for their suitability. Structural perturbations in BSA were reduced during the spray-freeze drying step by employing the excipient trehalose. The protein was then encapsulated into PLG microspheres under various conditions without inducing significant structural perturbations. BSA released from these microspheres had a similar monomer content as unencapsulated BSA and also the same secondary structure. Upon blending of a poloxamer (Pluronic F-68) with the polymer phase, in vitro release was characterized by a small initial release and a prolonged and continuous sustained phase. In conclusion, the developed o/o methodology coupled with FTIR spectroscopic monitoring of protein structure is a powerful approach for the development of sustained release microspheres.

Chromatography, High Pressure Liquid↗

Clinical application of GnRH-antagonists.

Due to the different pharmacological mode of action, GnRH-antagonists seem to open up new avenues to hormonal treatment in several indications. Although it may be still too early to speculate about the possible end of the era of GnRH-agonists, from what is known today, the advantages of GnRH-antagonists are most evident in our opinion. When the development of sustained delivery systems may continue and be completed, the antagonists will have a major potential within benign gynecological conditions and also in the treatment of malignancies such as prostatic, mammary, endometrial or ovarian cancer. Suitable sustained delivery systems and the development of GnRH-antagonists with sufficient oral bioavailability, represent the present and future challenge for these efforts.

Clinical Trials, Phase III as Topic↗