Characterization of poly(glycolide-co-D,L-lactide)/poly(D,L-lactide) microspheres for controlled release of GM-CSF

PURPOSE: This study describes the preparation and characterization of a controlled release formulation of granulocyte-macrophage colony-stimulating factor (GM-CSF) encapsulated in poly(glycolide-co-D,L-lactide) (PLGA) and poly(D,L-lactide) (PLA) microspheres. METHODS: GM-CSF was encapsulated in PLGA/PLA microspheres by a novel silicone oil based phase separation process. Several different blends of PLGA and low molecular weight PLA were used to prepare the microspheres. The microspheres and the encapsulated GM-CSF were extensively characterized both in vitro and in vivo. RESULTS: Steady release of GM-CSF was achieved over a period of about one week without significant "burst" of protein from the microspheres. Analysis of microsphere degradation kinetics by gel permeation chromatography (GPC) indicated that low molecular weight PLA enhanced the degradation of the PLGA and thereby affected release kinetics. GM-CSF released from the microspheres was found to be biologically active and physically intact by bioassay and chromatographic analysis. Analysis of serum from mice receiving huGM-CSF indicated that the GM-CSF was biologically active and that a concentration of greater than 10 ng/mL was maintained for a period lasting at least nine days. MuGM-CSF was not detected following in vivo administration of muGM-CSF microspheres. The tissues of mice receiving muGM-CSF microspheres were characterized by infiltration of neutrophils, and macrophages which were in significant excess of those found in mice administered with placebo controls (i.e. microspheres without GM-CSF). CONCLUSIONS: This study demonstrates the influence of formulation parameters on the encapsulation of GM-CSF in PLGA/PLA microspheres and its controlled release in biologically active form. The intense local tissue reaction in mice to muGM-CSF microspheres demonstrates the importance of the mode of delivery on the pharmacologic activity of GM-CSF.     

Garcinia cambogia (hydroxycitric acid) as a potential antiobesity agent: a randomized controlled trial

CONTEXT: Hydroxycitric acid, the active ingredient in the herbal compound Garcinia cambogia, competitively inhibits the extramitochondrial enzyme adenosine triphosphate-citrate (pro-3S)-lyase. As a citrate cleavage enzyme that may play an essential role in de novo lipogenesis inhibition, G cambogia is claimed to lower body weight and reduce fat mass in humans. OBJECTIVE: To evaluate the efficacy of G cambogia for body weight and fat mass loss in overweight human subjects. DESIGN: Twelve-week randomized, double-blind, placebo-controlled trial. SETTING: Outpatient weight control research unit. PARTICIPANTS: Overweight men and women subjects (mean body mass index [weight in kilograms divided by the square of height in meters], approximately 32 kg/m2). INTERVENTION: Subjects were randomized to receive either active herbal compound (1500 mg of hydroxycitric acid per day) or placebo, and both groups were prescribed a high-fiber, low-energy diet. The treatment period was 12 weeks. Body weight was evaluated every other week and fat mass was measured at weeks 0 and 12. MAIN OUTCOME MEASURES: Body weight change and fat mass change. RESULTS: A total of 135 subjects were randomized to either active hydroxycitric acid (n = 66) or placebo (n = 69); 42 (64%) in the active hydroxycitric acid group and 42 (61%) in the placebo group completed 12 weeks of treatment (P = .74). Patients in both groups lost a significant amount of weight during the 12-week treatment period (P<.001); however, between-group weight loss differences were not statistically significant (mean [SD], 3.2 [3.3] kg vs 4.1 [3.9] kg; P = .14). There were no significant differences in estimated percentage of body fat mass loss between treatment groups, and the fraction of subject weight loss as fat was not influenced by treatment group. CONCLUSIONS: Garcinia cambogia failed to produce significant weight loss and fat mass loss beyond that observed with placebo.     

A feasibility study evaluating rhBMP-2/absorbable collagen sponge device for local alveolar ridge preservation or augmentation

This two-center human clinical trial evaluated recombinant human bone morphogenetic protein-2 delivered in an absorbable collagen sponge (rhBMP-2/ACS) for either alveolar ridge preservation after tooth extraction or augmentation of localized osseous defects. This 24-month study comprised two parts: a 4-month acute safety and bone induction period (Part I) followed by a 20-month, osseointegration, functional restoration, and long-term safety evaluation (Part II). The primary objective of Part I, discussed in this article, was to evaluate the short-term safety and technical feasibility of the rhBMP-2 device implantation. Twelve patients (six preservation and six augmentation) were enrolled in the investigation. Patient safety was monitored by oral examinations, radiographs, and the collection of blood samples to measure serum chemistries, hematology, and potential antibody formation. Technical feasibility was evaluated by collecting information relating to the handling properties of the rhBMP-2/ACS device. The ability of various evaluative tools to measure the bone-inducing activity of the rhBMP-2/ACS device was also assessed. The clinical results suggested that rhBMP-2/ACS was well tolerated locally and systemically, with no serious adverse events. The device was found to be easily handled and adapted to the ridge and extraction socket. Using direct measurements, all sites demonstrated firmness and fullness to palpation at 4 weeks; however, a loss of volume was noted in some treatment areas between 4 and 8 weeks. Augmentation of the alveolar ridge was not observed in the patients as assessed by the evaluation techniques. This trial indicated that the use of rhBMP-2/ACS to preserve alveolar ridge after tooth extraction or augmentation of localized defects is safe and feasible. Bone fill was observed in all alveolar sockets filled with the rhBMP-2 device.     

Biological warfare. A historical perspective

Several modifications of the 3H-tetracycline bone labeling method for measuring whole skeleton bone resorption were tested. Under steady state conditions of whole skeleton resorptive activity, bone labeling for intervals longer than 2 weeks prior to experimentation did not significantly alter the urinary 3H-tetracycline loss curve. The utilization of nonlinear regression analysis showed that the urinary loss of 3H-tetracycline was best described by double exponential equations, indicating the loss of label from two distinct and independent exchangeable bone compartments. This conclusion was supported by the finding that soft tissues were effectively depleted of 3H-tetracycline by 24 hours after the final injection of label. Hence, it was concluded that approximately 40% of the 3H-tetracycline loss from skeletal bone is associated with a "fast" compartment which is depleted within 6 or 7 days after label loading. The size and rate of 3H-tetracycline loss from the fast compartment decreased (40%) with age such that the depletion time remained constant between 8 and 24 weeks of age in both male and female rats. The remaining 60% of 3H-tetracycline loss from a "slow" compartment which was depleted in about 70 days in young (8 week) rats. This compartment, which is believed to reflect cell-mediated resorption of calcified bone; decreased in size with age in both male (50%) and female (30%) rats. The rate of label loss from this compartment, however, remained relatively high so that the depletion time decreased (approximately 35%) between 8 and 24 weeks of age. By determining whole skeletal mass and calculating these parameters on the basis of skeletal mass, we were further able to demonstrate significantly higher resorptive activity in female than in male rats by 24 weeks of age.     

Radical prostatectomy and prognostic factors

We investigated ectopic bone formation by biphasic calcium phosphate (BCP) combined with recombinant human bone morphogenetic protein-2 (rhBMP-2) in the rat dorsum. Under reduced pressure, rhBMP-2 was adsorbed onto BCP, which consisted of 80% beta-tricalcium phosphate and 20% hydroxyapatite uniformly distributed in granules. Twenty Wistar rats were separated into 4 groups consisting of 5 animals each dosed with 2, 10, and 50 micrograms/700 microliters of rhBMP-2 and a control group (BCP only). Pieces of the BCP-BMP complex or only BCP were implanted under the dorsal skin of the rats. Histological sections were examined three weeks later. New bone was formed in all rats given 50 micrograms doses, but not in the 2 micrograms and control groups. These results indicated that BCP combined with rhBMP-2 induced ectopic bone formation without additional carriers. Therefore, BCP granules alone can function as carriers for rhBMP-2 to induce bone formation.     

Intake of selected micronutrients and risk of colorectal cancer

We fabricated poly(DL-lactic-co-glycolic acid) (PLGA) 50:50 microparticles loaded with an antisense (AS) oligodeoxy-nucleotide (ODN) against the rat tenascin mRNA and determined the effect in vitro of the AS-ODN released on smooth muscle cell (SMC) proliferation and migration. AS-ODN was entrapped using a double-emulsion-solvent-extraction technique with high efficiency. Release of AS-ODN was characterized by a small initial-burst effect followed by a period of controlled AS-ODN release for up to 20 days. SMC proliferation studies exhibited dose-dependent growth inhibition with AS-ODN-loaded microparticles. Microparticles loaded with scrambled (SC) ODN showed less growth inhibition than AS-ODN. Moreover, only the AS-ODN-loaded microparticles inhibited migration. These results demonstrate the feasibility of entrapping an AS-ODN to rat tenascin in PLGA microparticles for controlled delivery to inhibit SMC proliferation and migration.     

Development of a single-shot subunit vaccine for HIV-1. 2. Defining optimal autoboost characteristics to maximize the humoral immune response

The design of a single-shot subunit vaccine for HIV-1 with polylactic-coglycolic acid (PLGA) sustained-release technology to effect an autoboost of antigen (MN gp120) at a given time after the primary immunization requires in-depth knowledge about the timing, the duration, and the need for coadjuvant in the autoboost. These questions cannot be answered unambiguously with PLGA microspheres, so we have conducted studies using Alzet minipumps to release antigen at prescribed times to mimic a PLGA autoboost. The results show that a discrete autoboost is preferred over continuous release of antigen, that the time profile of the autoboost (whether pulsatile or a 2-week continuous release) does not affect the booster immune response, and that only antigen is required in the booster immunization (a coadjuvant in the boost does not give higher titers).     

Interlobe communication in multiple calcium-binding site mutants of Drosophila calmodulin

The purpose of this study was to investigate the efficacy of BCP granules combined with rhBMP-2 for ectopic bone formation in rats. BCP granules were used as a carrier for rhBMP-2. The rhBMP-2 was adsorbed to BCP granules under the reduction of pressure. Twenty Wistar rats were used for this experiment and were divided into 4 groups according to the concentration (0,2,10,50 micrograms/700 microliters) of rhBMP-2 implanted in each rat. The BMP and BCP complex was implanted under the dorsal skin of the rats. Three weeks after the implantation, the rats were sacrificed. The experimental sites were immediately dissected and histological sections were prepared. In the 50 micrograms group, new bone formation was observed in all rats, while bone tissue was not found in the 2 micrograms and 0 microgram groups. These results indicated that BCP combined with rhBMP-2 could effectively induce ectopic bone formation. It was suggested that BCP granules alone could be applicable as a carrier for rhBMP-2 in order to induce new bone formation.     

A method for detecting changes in left ventricular mass during variations in filling volume

The study reported describes a combination of recombinant human bone morphogenetic protein-2 (rhBMP-2) and collagen (C) to regenerate bone. Unilateral critical-sized defects (CSDs) were prepared in radii of 32 skeletally mature New Zealand white rabbits. Rabbits were divided evenly among four treatments: autograft, absorbable C (Helistat), 35 microg of rhBMP-2 combined with absorbable C (rhBMP-2/C), and untreated CSDs. The two euthanasia periods were 4 and 8 weeks. Radiographs were taken the day of surgery, every 2 weeks, and at term and the percent of radiopacity was measured. Data analysis revealed a time-dependent increase in the percent radiopacity with rhBMP-2/C. Histological examination revealed the rhBMP-2/C treatment regenerated osseous contour by 8 weeks. According to quantitative histomorphometry, the CSD and C groups had significantly less new bone than either autograft or rhBMP-2/C (p < or = 0.05). The results suggest that rhBMP-2/C could be an effective therapy to restore segmental bone defects.     

Adeno-associated virus vector containing the herpes simplex virus thymidine kinase gene causes complete regression of intracerebrally implanted human gliomas in mice, in conjunction with ganciclovir administration

Weight gain is a major side-effect of treatment with clozapine. In order to investigate the influence of the atypical neuroleptic clozapine on leptin secretion, serum leptin levels were measured in 12 patients at baseline and for a 10-week period after initiation of treatment. Serum clozapine levels and levels of its metabolites were simultaneously assessed. Alterations of body weight and body composition were determined. During the 10-week observation period leptin levels differed significantly from the levels determined at baseline (P < 0.0001). During the first 2 weeks of treatment serum leptin levels at least doubled in eight of the 12 patients. The maximal relative increase over baseline was 536%. Low doses of clozapine were sufficient to induce this effect. Within a 10-week period mean body weight, mean body mass index, mean fat mass and mean lean body mass all increased. Based on the results we suggest that in predisposed individuals clozapine induces an increased appetite; overeating and weight gain can ensue, which in turn underlie elevated leptin secretion.     

Mice lacking smooth muscle calponin display increased bone formation that is associated with enhancement of bone morphogenetic protein responses

BACKGROUND: Calponin is a calmodulin-and actin-binding protein expressed in smooth muscle. It promotes actin polymerization and inhibits actin-activated myosin ATPase activity. Despite the molecular and functional characterization of calponin in vitro, the physiological role of calponin in vivo has not been clarified. RESULTS: We investigated the in vivo function of smooth muscle calponin (also called basic calponin or calponin h1) by generating mice carrying a targeted mutation in both alleles of the calponin gene. Mice lacking basic calponin expression displayed enhanced ectopic bone formation in vivo, induced by recombinant human bone morphogenetic protein-2 (rhBMP-2), and an augmentation of the degree of osteoblastic differentiation of embryonic mesenchymal cells when they were stimulated by rhBMP-2. Basic calponin messenger RNA was shown to be expressed in developing and healing bone tissues, and in undifferentiated MC3T3-E1 osteoblasts. An examination of the skeletons of mutated mice showed an early onset of cartilage formation and ossification, and increased postnatal bone formation characterized by an increase in the number of activated periosteal osteoblasts. Bone fracture healing was accelerated in mutated mice. CONCLUSION: This is the first demonstration of animals with enhanced BMP responsiveness in host cells, suggesting that endogenous basic calponin may play a negative role in an osteogenic programme.     

Tissue distribution of DNA adducts in rats treated by intramammillary injection with dibenzo[a,l]pyrene, 7,12-dimethylbenz[a]anthracene and benzo[a]pyrene

Recombinant human bone morphogenetic protein (rhBMP-2) was examined for its in vitro effects on biochemical markers representing osteoblast phenotype. Primary cultures of fetal rat calvarial osteoblasts were used in this study. The results indicated that rhBMP-2 stimulated alkaline phosphatase activity, parathyroid hormone (PTH)-induced cyclic AMP production, and collagen biosynthesis in a dose-dependent manner in confluent cultures. The percent collagen synthesis also increased in a dose-dependent manner. Alkaline phosphatase activity was stimulated in a time-dependent manner by rhBMP-2 that reached its maximum 5 days after initiation. Cycloheximide (2 micrograms/ml) inhibited rhBMP-2-stimulated alkaline phosphatase indicating de novo protein synthesis of the enzyme. Transforming growth factor-beta 1 (TGF-beta 1)-induced inhibition of alkaline phosphatase activity observed in confluent primary cultures was completely abolished by rhBMP-2 at a concentration that was 43 times greater than the TGF-beta 1 concentration. Also, rhBMP-2 produced a small stimulation of alkaline phosphatase activity in cells grown in the absence of ascorbic acid; however, the effect was greatly enhanced in cells cultivated in the presence of ascorbic acid (50 micrograms/ml). In view of the potentiating effect of ascorbic acid on rhBMP-2-induced stimulation of alkaline phosphatase, we speculate that ascorbic acid could amplify the osteoinductive effects of rhBMP-2 and thereby augment the efficacy of the BMP when used as bone repair material in vivo. rhBMP-2 (4.3-86 ng/ml) did not exhibit mitogenic effects on cultured osteoblasts. These data suggest that rhBMP-2 has the ability to induce expression of various markers associated with the osteoblast phenotype in primary cultures of fetal rat calvarial osteoblasts. In addition, we speculate that TGF-beta 1 may play a regulatory role in BMP-induced bone formation and ascorbic acid may potentiate the effects of rhBMP-2 in vivo.     

Development of a multiple-drug delivery implant for intraocular management of proliferative vitreoretinopathy

A prototype multiple-drug delivery implant has been developed for the intraocular management of proliferative vitreoretinopathy (PVR). Because of the recurrent nature of the disease, PVR causes blindness in approximately 7% of patients who have undergone retinal re-attachment surgery. The poly(dl-lactide-co-glycolide) 50/50 (PLGA) implant consists of three cylindrical segments, each of which contains one of the following drugs: 5-fluorouridine (5FUrd, an antimetabolite), triamcinolone (Triam, a corticosteroid), and human recombinant tissue plasminogen activator (t-PA, a thrombolytic agent). The device can be inserted through a 20-gauge syringe needle into the vitreous body of the eye. The implant also possesses a PLGA coating over the t-PA-containing terminal segment, which creates a lag-time to deliver t-PA when most needed and to decrease the risk of postoperative bleeding. Two methods of cylinder fabrication were investigated: heat and solvent extrusion. The release behavior of several drugs was examined as a function of the processing variables including: extrusion method, drug loading, polymer molecular weight, and drug particle size. The presence of either the organic solvent (acetone) during processing or a highly water-soluble drug (5FUrd) in the formulation increased the polymer porosity, which in turn, increased the drug release-rate. Drug loading effects were consistent with percolation concepts, and a low-molecular-weight PLGA (e.g., Mw=42000 for inherent viscosity=0.58 dl/g) was desirable to produce controlled release close to one month. Based on pharmacological and pharmacokinetic data of these compounds and our clinical experience with this disease, several design criteria for a combined implant were devised. Optimal cylindrical segments from the formulation studies were selected and combined in series to form a contiguous implant. After successful combination and coating procedures were developed, prototype implants were prepared. From the 3-drug prototype, 5FUrd and Triam were released approximately 1 microgram/day for over 4 weeks and 10-190 microgram/day over 2 weeks, respectively. The solvent-extrusion procedure did not significantly alter the stability of the encapsulated t-PA (>94+/-5% serine protease activity after preparation). After a lag-time of approximately 2 days, t-PA was released active at a rate of approximately 0.2-0.5 microgram/day in approximately 2 weeks. The release characteristics from the combined implant largely met our initial design criteria. Hence, controlled-release implants of this kind may have potential use for intraocular treatment of PVR.     

Femoral neck osteopenia in patients with inflammatory bowel disease

Bone morphogenetic proteins (BMPs) are considered to have important regulatory roles in skeletal embryogenesis and bone healing. Recombinant human BMPs (rhBMPs) have been shown to heal critical size defects and promote spinal fusion. We studied the effects of rhBMP-2 in an absorbable collagen sponge (ACS) on bone healing in a large animal tibial fracture model. Bilateral closed tibial fractures were created in 16 skeletally mature goats and reduced and stabilized using external fixation. In each animal, one tibia received the study device (0.86 mg of rhBMP-2/ACS or buffer/ACS), and the contralateral fracture served as control. The device was implanted as a folded onlay or wrapped circumferentially around the fracture. Six weeks following fracture, the animals were sacrificed and the tibiae harvested for torsional testing and histomorphologic evaluation. Radiographs indicated increased callus at 3 weeks in the rhBMP-2/ACS treated tibiae. At 6 weeks, the rhBMP-2/ACS wrapped fractures had superior radiographic healing scores compared with buffer groups and controls. The rhBMP-2/ACS produced a significant increase in torsional toughness (p = 0.02), and trends of increased torsional strength and stiffness (p = 0.09) compared with fracture controls. The device placed in a wrapped fashion around the fracture produced significantly tougher callus (p = 0.02) compared with the onlay application. Total callus new bone volume was significantly increased (p = 0.02) in the rhBMP-2/ACS fractures compared with buffer groups and controls regardless of the method of device application. The rhBMP-2/ACS did not alter the timing of onset of periosteal/endosteal callus formation compared with controls. Neither the mineral apposition rates nor bone formation rates were affected by rhBMP-2/ACS treatment. The increased callus volume associated with rhBMP-2 treatment produced only moderate increases in strength and stiffness.     

Recombinant human bone morphogenetic protein-2 stimulates osteoblast differentiation and suppresses matrix metalloproteinase-1 production in human bone cells isolated from mandibulae

Bone morphogenetic protein (BMP), a member of the transforming growth factor superfamily, is one of the most potent growth factors that stimulate osteoblast differentiation and bone formation. We investigated the effects of recombinant human BMP-2 (rhBMP-2) on osteoblast differentiation and matrix metalloproteinase-1 (MMP-1) production in human bone cells (HBC) isolated from mandibulae of 3 adult patients. rhBMP-2 at concentrations over 50 ng/ml significantly stimulated alkaline phosphatase activity and parathyroid hormone (PTH)-dependent 3', 5'-cyclic adenosine monophosphate accumulation, which are early markers of osteoblast differentiation, in HBCs. rhBMP-2 (500 ng/ml) also enhanced the level of PTH/PTH related-peptide receptor mRNA expression in HBCs. Although neither HBCs untreated nor treated with rhBMP-2 produced measurable amounts of osteocalcin, which is a marker of more mature osteoblasts, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] induced ostocalcin mRNA expression and its protein synthesis in these cells. rhBMP-2 inhibited 1,25(OH)2D3-induced osteocalcin synthesis in HBCs at both the mRNA and protein level. rhBMP-2 also significantly suppressed MMP-1 production and MMP-1 mRNA expression at concentrations over 500 ng/ml. These results suggest that rhBMP-2 exerts anabolic effects on human osteoblastic cells derived from mandibulae by stimulation of osteoblast differentiation and down-regulation of MMP-1 synthesis.     

A metabolic syndrome in whites and African-Americans. The Atherosclerosis Risk in Communities baseline study

The efficacy of microspheres made of polylactic acid polyglycolic acid copolymer mixed with blood clot as a delivery system for recombinant human bone morphogenetic protein-2 (rhBMP-2) was evaluated and the long term behaviour of rhBMP-2 in rats was studied. Twenty micro grams of rhBMP-2 in 200 microliter carrier (blood coagulum and polylactic acid polyglycolic acid porous microspheres) were implanted subcutaneously over both sides of the chest muscles in 40 5-week-old male Long Evans rats. The control group were implanted with carrier alone. Specimens were retrieved after 3 days and weekly for 9 weeks. Outcome was measured by signs of bone formation on low power radiographs, and signs of bony growth on histological examination. There were no signs of foreign body or inflammatory reactions to the carrier in either group. In the experimental group signs of bone formation had started to appear by the end of the first week, and there was a gradual increase in both radio-opacity and size during the observation period. Histologically the bony growth was beginning to mature by 4 weeks and was fully mature by 7-9 weeks. In contrast there was no sign of cartilage or bone formation in the control group and the carrier had resorbed by 4-6 weeks. It is concluded that rhBMP-2 implanted in a carrier consisting of blood clot and porous microspheres made of polylactic acid polyglycolic acid induces rapid proliferation of mesenchymal cells that lead to formation of cartilage and bone by 7 days which had matured by 9 weeks. rhBMP-2 in this carrier may be useful clinically because of its capacity to induce early formation of bone.     

Manufacture of porous biodegradable polymer conduits by an extrusion process for guided tissue regeneration

We have fabricated porous, biodegradable tubular conduits for guided tissue regeneration using a combined solvent casting and extrusion technique. The biodegradable polymers used in this study were poly(DL-lactic-co-glycolic acid) (PLGA) and poly(L-lactic acid) (PLLA). A polymer/salt composite was first prepared by a solvent casting process. After drying, the composite was extruded to form a tubular construct. The salt particles in the construct were then leached out leaving a conduit with an open-pore structure. PLGA was studied as a model polymer to analyze the effects of salt weight fraction, salt particle size, and processing temperature on porosity and pore size of the extruded conduits. The porosity and pore size were found to increase with increasing salt weight fraction. Increasing the salt particle size increased the pore diameter but did not affect the porosity. High extrusion temperatures decreased the pore diameter without altering the porosity. Greater decrease in molecular weight was observed for conduits manufactured at higher temperatures. The mechanical properties of both PLGA and PLLA conduits were tested after degradation in vitro for up to 8 weeks. The modulus and failure strength of PLLA conduits were approximately 10 times higher than those of PLGA conduits. Failure strain was similar for both conduits. After degradation for 8 weeks, the molecular weights of the PLGA and PLLA conduits decreased to 38% and 43% of the initial values, respectively. However, both conduits maintained their shape and did not collapse. The PLGA also remained amorphous throughout the time course, while the crystallinity of PLLA increased from 5.2% to 11.5%. The potential of seeding the conduits with cells for transplantation or with biodegradable polymer microparticles for drug delivery was also tested with dyed microspheres. These porous tubular structures hold great promise for the regeneration of tissues which require tubular scaffolds such as peripheral nerve, long bone, intestine, or blood vessel.     

In vivo characteristics of injectable poly(DL-lactic acid) microspheres for long-acting drug delivery

Poly(DL-lactic acid) (PLA) microspheres containing testosterone (T) were prepared by the solvent evaporation process to evaluate their physical properties such as size distribution, shape, drug content, in vivo controlled drug release, pharmacological influences on the prostate gland in castrated rats, and histopathological findings of tissues surrounding the implants. The in vivo release of T from PLA microspheres containing 30 mg of drug obtained with chloroform was continued over a 6-week period. This effect is attributed to high dispersibility of T in the device when obtained with chloroform. Both serum drug levels and prostate gland weight recovery suggested the effects of a long-acting drug delivery system. The histopathological findings showed that the devices used were completely degraded 10 weeks after injection.     

Controlled release of lidocaine from injectable gels and efficacy in rat sciatic nerve block

PURPOSE: Methods of delaying the action of local anesthetics are important, since short duration of action limits their use in the treatment of postoperative and chronic pain. The present study evaluated the use of low-viscosity gels in prolonging the release of lidocaine. METHODS: Release of lidocaine from 2% lidocaine.HCl containing methylcellulose (MC), hydroxypropylmethylcellulose (HPMC), sodiumcarboxymethyl cellulose (CMC), and poloxamer 407 (PO) gels was studied in phosphate buffer, pH 7.4, at 37 degrees C. Commercial metylcellulose gel (MCcom) served as control. The in vivo efficacy of the respective gel formulations were evaluated in rats. The gel was injected into the vicinity of the sciatic nerve and nociception and motor function were tested. RESULTS: The cumulative amount of lidocaine released during 8 hr was slowest from the PO gel, followed by the CMC, HPMC and MC gels. The antinociceptive effect was not prevented by the motor block and lasted longest with the PO gel. Good linear and rank order correlation was obtained between in vitro and in vivo results. The microscopic examination of the tissue samples revealed only mild or no irritation of the skeletal muscle tissue by the PO, HPMC, and CMC gels. CONCLUSIONS: Based on these results poloxamer gel proved to be the most promising carrier for lidocaine.     

Review of autologous and allogeneic blood transfusion practices in patients undergoing radical hysterectomy

We investigated the short-term recuperation of bone mass during skeletal reloading after a period of unloading in young rats. One hind limb of 4-week-old rats was either unloaded irreversibly by sciatic neurectomy, or unloaded reversibly by external fixation. Other animals were sham-operated. After 9 days, the fixation-unloaded limbs were reloaded for 1-3 weeks and were compared with the hind limbs of age-matched unloaded (neurectomized) and sham-operated controls. Cortical and cancellous bone mass was measured using ashing and histomorphometry. Cortical bone mass (expressed as femoral dry and ash weight and tibial cortical bone area) was reduced in both unloaded groups and was accompanied by production of hypomineralized bone, as shown by a reduction in the percent ash of the dry weight. Cancellous bone mass (expressed as bone area and surface at the tibial metaphysis) was also reduced in both unloaded groups. Cortical bone mass deficit was greater in the fixation group than in the neurectomy group. Thereafter it increased in the neurectomy group despite a normal longitudinal growth rate, but returned to age-matched values in the reloaded group by 3 weeks. The changes in tibial cancellous bone mass were more pronounced but followed a similar pattern and normalized by 2 weeks. These data demonstrate that total unloading produced by external fixation causes a greater degree of bone mass deficit than partial unloading (produced by neurectomy); the rate of bone loss during unloading in the rat hind limb is more rapid than its recovery during reloading; and cancellous bone recuperates during the reloading phase faster than does cortical bone.