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PubMedDate not supplied

Effect of emulsifier blend on the characteristics of sustained release diclofenac microspheres.

This investigation involved the evaluation of the emulsifier blend effect on the development of sustained release diclofenac microspheres intended for use in a suspension formulation. The microspheres were prepared using the hydrophobic congealable disperse phase method. The emulsifier blend consisted of glycerol, monostearate (GMS), a hydrophobic emulsifier with HLB = 3.8, and Tween 80, a hydrophilic emulsifier with a HLB value of 15. The effect of this blend on the encapsulation efficiency, size distribution and drug release from the microspheres was studied. A critical amount of GMS (> 0.2 g) was found to be necessary for good encapsulation efficiency. X-ray diffractograms revealed that the drug retains its crystalline state within the microspheres, indicating that the drug is present as a dispersion within the wax matrix. Increasing amounts of Tween 80 caused an increase in the drug release while increased amounts of GMS retarded the release. The hydrophilic emulsifier and the emulsifier blend influenced the size distribution of the formed microspheres. With an increase in the amount of hydrophilic emulsifier, there was an initial increase in the percent of desired size fraction (137.5 microns) of microspheres followed by a decrease. Microspheres with a larger size released the drug slowly compared to smaller size microspheres, while increase in drug load increased the rate of drug release. The release pattern fitted the Higuchi dissolution kinetics for spherical matrices. Different impeller blade designs formed microspheres that exhibited different release rates. The microspheres (mean size 137.5 microns), had a release profile that made them suitable to be formulated as a sustained release suspension.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2001

Transfection by polyethyleneimine-coated microspheres.

UNLABELLED: Polyethyleneimine (PEI) can be used as a DNA delivery mechanism in cell culture and in vivo. Cells can be transfected by using surface-bound PEI, as well as by PEI/DNA microparticles. In the present experiments we extended these observations by preparing microspheres with covalently attached PEI. Blends of poly(epsilon-CBZ-L-lysine) mixed with poly(D,L-lactic-co-glycolic acid) were formed into microspheres using a double-emulsification/solvent evaporation procedure. CBZ (carbobenzoxy) groups on the surface of microspheres were removed by Li(0) /liquid ammonia reduction. Surface amino groups were used for covalent attachment of PEI and other molecules. Silica microspheres with bonded-phase PEI were also used. Microspheres were mixed with plasmid DNA encoding green fluorescent protein and added to cultured cells. PEI-coated microspheres transfected cultured Caco cells and MH-S alveolar macrophages. Expression of the transfected DNA increased over several days. MH-S cells phagocytosed PEI-coated silica microspheres, which were shown to reside in an acidic subcellular compartment. This was demonstrated by conjugating a pH-sensitive fluorescent dye (seminaphthofluorescein, SNAFL) to the microsphere surface. Transfection of MH-S cells was increased when plasmid DNA was complexed with histone on the surface of the microspheres. CONCLUSION: PEI-coated microspheres have potential as a DNA delivery device with advantages of the unique properties of PEI and ease of surface chemical modification.

3T3 Cells↗
PubMed1996

Evaluation of PLGA microsphere size effect on myotoxicity using the isolated rodent skeletal muscle model.

The present work investigated the magnitude of microsphere-induced acute myotoxicity and determined whether this myotoxicity is related to microsphere size and/or reconstitution solvent. Using a high molecular weight poly(dl-lactide-co-glycolide) copolymer, the myotoxicity of two different size microsphere formulations (3.6 microns and 19 microns) in normal saline or distilled water was quantified using a previously validated isolated rat muscle system. Overall, microspheres were found to be relatively nontoxic compared to known myotoxic agents (e.g., phenytoin) and control muscles. The smaller microspheres were found to be significantly more myotoxic than larger microspheres. Furthermore, the myotoxicity was lower in large microspheres reconstituted with normal saline or normal saline with 0.5% (w/v) carboxymethylcellulose (to prevent aggregation) compared to those reconstituted with distilled water. Smaller microspheres were found to be extremely difficult to inject, due to aggregation, which could not be prevented by the addition of carboxymethylcellulose. This study suggests that larger microspheres are less myotoxic than smaller microspheres.

Animals↗
PubMed2005

Intravitreous injection of PLGA microspheres encapsulating GDNF promotes the survival of photoreceptors in the rd1/rd1 mouse.

PURPOSE: To evaluate the potential delay of the retinal degeneration in rd1/rd1 mice using recombinant human glial cell line-derived neurotrophic factor (rhGDNF) encapsulated in poly(D,L-lactide-co-glycolide) (PLGA) microspheres. METHODS: rhGDNF-loaded PLGA microspheres were prepared using a water in oil in water (w/o/w) emulsion solvent extraction-evaporation process. In vitro, the rhGDNF release profile was assessed using radiolabeled factor. In vivo, rhGDNF microspheres, blank microspheres, or microspheres loaded with inactivated rhGDNF were injected into the vitreous of rd1/rd1 mice at postnatal day 11 (PN11). The extent of retinal degeneration was examined at PN28 using rhodopsin immunohistochemistry on whole flat-mount retinas, outer nuclear layer (ONL) cell counting on histology sections, and electroretinogram tracings. Immunohistochemical reactions for glial fibrillary acidic protein (GFAP), F4/80, and rhodopsin were performed on cryosections. RESULTS: Significant delay of rod photoreceptors degeneration was observed in mice receiving the rhGDNF-loaded microspheres compared to either untreated mice or to mice receiving blank or inactivated rhGDNF microspheres. The degeneration delay in the eyes receiving the rhGDNF microspheres was illustrated by the increased rhodopsin positive signals, the preservation of significantly higher number of cell nuclei within the ONL, and significant b-wave increase. A reduction of the subretinal glial proliferation was also observed in these treated eyes. No significant intraocular inflammatory reaction was observed after the intravitreous injection of the various microspheres. CONCLUSIONS: A single intravitreous injection of rhGDNF-loaded microspheres slows the retinal degeneration processes in rd1/rd1 mice. The use of injectable, biodegradable polymeric systems in the vitreous enables the efficient delivery of therapeutic proteins for the treatment of retinal diseases.

Animals↗
PubMed2006

[The dynamic study of retinoic acid and its alginate sodium microspheres in rabbit eye].

OBJECTIVE: To obtain a intravitreous delay release system by injection of biodegradable polymers (alginate sodium-retinoic acid microspheres, AGS-RA microspheres) to the rabbit vitreous and study the release character of RA delivery system in vitro. METHODS: RA was mixed with 1.5% alginate sodium and microspheres was made by a special electrostatic generator after dissolved in organic solvent; The content of AGS-RA in the microspheres and its release from the microspheres were measured by spectrophotometer. The characteristic of the metabolic dynamics of AGS-RA in the microspheres was analyzed by HPLC. RESULTS: The size of microspheres we manufacture is (95.2443 +/- 8.6265) microm; Medicine contain quantity of RA is (1.7644 +/- 0.0453) microg/mg; Vitro test show that RA in the microspheres is release evenly in the 28 days of observation; Inject medicine to vitreous cavity show no poisonous side effect; The medicine dynamics research of microspheres showed that medicine is being even in 6 weeks releasing [the aqueous RA density of 1, 3 d, 1, 2, 3, 4, 5, 6 weeks is (23.79 +/- 0.15), (33.45 +/- 0.48), (19.95 +/- 0.79), (21.12 +/- 0.47), (19.65 +/- 0.35), (20.01 +/- 0.25), (18.24 +/- 0.27), (18.5 +/- 0.68) ng/ml, respectively]. Just in the 3rd day there is a release summit. CONCLUSION: In vivo and in vitro tests show that AGS-RA microspheres can delay RA release uniformity.

Alginates↗
PubMed1990

An experimental model of chronic renal disease in dogs by infusion of microspheres into the renal arterial circulation.

The feasibility of renal arterial infusion of nonbiodegradable microspheres as a model of chronic renal disease in dogs was evaluated. Resin-coated, styrene-divinyl benzene copolymer microspheres were infused into the kidneys of healthy adult Beagles by direct injections of both renal arteries in a single surgical procedure. Injections of 25-microns diameter microspheres had minimal effect on either the clinical status or serum values of the dogs. Histologic examination revealed the majority of the microspheres lodged within the capillary beds of the glomeruli, and little change to the kidneys. However, injections of 50-microns diameter microspheres caused significant increases in serum concentrations of urea nitrogen and creatinine. Histologically, the larger microspheres obstructed afferent arterioles and small arteries, which caused diffuse glomerular necrosis and nephron damage. With doses ranging from 1 to 3 million microspheres/dog, a correlation between the quantity of microspheres injected and severity of renal damage was observed. The optimal dose for producing a model of moderate renal disease was determined to be 1.8 million microspheres/dog (0.9 million microspheres/kidney). During long-term studies, microsphere-injected dogs fed a moderately restricted protein ration remained relatively azotemic, compared with control dogs on the identical ration. During the 5-month postsurgical period, the serum urea nitrogen concentration averaged 18.41 +/- 1.59 mg/dl (mean +/- SE) for the microsphere-injected dogs vs 9.31 +/- 0.38 for the control dogs (P less than 0.001). Similarly, the mean serum creatinine value was significantly higher (P = 0.020) for the microsphere-injected dogs, compared with the controls (1.23 +/- 0.12 mg/dl vs 0.94 +/- 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1996

Intestinal absorption of PLAGA microspheres in the rat.

Rhodamine B-labelled poly (DL-lactide-co-glycolide) (PLAGA) microspheres of 2 different sizes, 1-5 microns and 5-10 microns, were administered as a single dose (1.44 x 10(9) and 1.83 x 10(8) particles, respectively) into the ileal lumen of adult rats. The content of rhodamine in the mesenteric vein and ileal lumen was analysed periodically from 10 min to 48 h as well as the distribution of microspheres in the intestinal mucosa and various other tissues. The concentration of rhodamine decreased progressively in the intestinal lumen and was negligible after 24 h. The number of microspheres in the mesenteric vein increased rapidly and reached a maximum after 4 h whatever the size of the particles. It then decreased progressively, but more rapidly with microspheres > 5 microns than with microspheres < 5 microns. The absorption efficiency was low for the former batch (about 0.11% of the administered dose) and higher for the latter (about 12.7%). The intraileal administration of free rhodamine B was followed by intense labelling of the epithelial cells and basement membranes in mesenteric lymph nodes, spleen, kidney and liver. PLAGA microspheres mainly crossed the intestinal mucosa at the site of Peyer's patches where microspheres of < 5 microns appeared after 3 h. Microspheres > 5 microns were retained in the ileal lumen. A few small microspheres were occasionally observed in the epithelial cells. Only the smallest particles were recovered in the liver, lymph nodes and spleen while basement membranes were always labelled. It is concluded that PLAGA microspheres could be useful for the oral delivery of antigens if their size is between 1 and 5 microns.

Animals↗
PubMed1997

Heterogeneous distribution of technetium-99m-labeled microspheres in rat lungs: microautoradiographic evidence and dosimetric consequences.

UNLABELLED: The heterogeneity of 99mTc-labeled microspheres distribution within rat lung was visualized and quantified using a microautoradiographic "track" method (MAR). METHODS: MAR was used to study the uptake of radioactivity by individual microspheres, thereby enabling calculation of the range of particle activity. MAR was also used to visualize in rat lung sections the intrapulmonary distribution of the microspheres within the lungs after intravenous administration. The mean doses delivered to the cells in close contact with the labeled microspheres were calculated taking only the 99mTc electron emissions into account. RESULTS: All the microspheres were labeled. Nevertheless, the spectrum of visible tracks varied by a factor of 10, inducing a variable activity per microsphere from < 36 Bq to 325 Bq (mean activity-94 Bq/microsphere). No correlation existed between the radioactivity uptake and the size of microspheres. A very heterogeneous tridimensional distribution of the microspheres within the lungs were demonstrated with interparticle distances ranging from 57-4400 microns. On the other hand, only 1 of 2000 rat lung capillaries was obstructed. Using the mean activity, calculated delivered doses were found to reach approximately 6 Gy for the closest endothelial cells and 2 Gy for epithelial cells. However, such high doses were delivered to only a few cells. CONCLUSION: The number of obstructed capillaries in human lungs is lower than in rat lungs; the distances between microspheres should be larger. Nevertheless, the individual doses absorbed by the pulmonary cells closest to the microspheres should be very important.

Animals↗
PubMed1997

Collagen-coated acrylic microspheres for embolotherapy: in vivo and in vitro characteristics.

PURPOSE: To evaluate the in vivo and in vitro properties of collagen-coated acrylic microspheres and to compare them with polyvinyl alcohol (PVA) particles. METHODS: Samples of 100- to 300-microns, 300- to 500-microns, 500- to 700-microns, and 700- to 900-microns collagen-coated acrylic microspheres and 200- to 300-microns PVA particles were suspended in solutions of 50% saline and 50% contrast material. The samples were evaluated for quantitative and qualitative microscopic characteristics (shape, size, deformability); injectability via standardized microcatheters; degree of particulate penetration in the pig rete mirabile; and reaction of tissue to the particles in 48-hour- and 4-week-old specimens. RESULTS: The acrylic microspheres were spherical and deformable. The sample of 100- to 300-microns microspheres (n = 202) had a mean diameter of 210 microns (standard deviation, 43 microns). Hub accumulation, particle aggregation, and catheter occlusion were not observed with the microspheres (all sizes) but were noted with the PVA particles. The 200- to 300-microns PVA particles formed aggregates in the proximal rete. The 100- to 300-microns microspheres were found throughout the rete and beyond. Chronic transmural and perivascular inflammation was observed with the microspheres and the PVA particles. CONCLUSIONS: Particle aggregation and catheter occlusion do not complicate the transcatheter delivery of collagen-coated acrylic microspheres as they do with PVA particles. For a given particle and vessel size, acrylic microspheres penetrate to a much greater extent than the PVA particles. Tissue reaction to acrylic microspheres and PVA particles is similar.

Acrylic Resins↗
PubMed1997

Fluorescent microsphere imaging: a particle-tracking approach to the hemodynamic assessment of the retina and choroid.

BACKGROUND AND OBJECTIVES: Quantitative assessment of choriocapillaris circulation has proven difficult. Although the fluorescent vesicle system provides a means of quantifying the retinal circulation, the attempts at imaging fluorescent liposomes in the choroidal microcirculation have been largely unsuccessful. The authors introduce a new tool, fluorescent microsphere imaging, and examine its utility for evaluating the hemodynamics of the retina and choroidal microcirculation. The usefulness of fluorescent microsphere imaging is demonstrated through the examination of the retinal and choroidal circulations of three rhesus monkeys. MATERIALS AND METHODS: Fluorescent microsphere imaging uses polystyrene latex microspheres that incorporate one or more dyes. These microspheres are injected intravenously into an animal and are excited in the eye through the resident lasers of a scanning laser ophthalmoscope. The excited particles are detected by the ophthalmoscope, and its output is then digitized directly or recorded on a videocassette recorder for subsequent image analysis. Multiple-dye microspheres use the principle of resonance energy transfer for the activation of the final dye in a non-radiative cascade. These microspheres enable the investigator to tailor the excitation and emission spectra of the particles for the investigation of different ocular tissues. RESULTS: Using 488/515 microspheres (excitation and emission peaks at 488 nm and 515 nm, respectively), the authors captured images of particles circulating in the perimacular retinal circulation. Shifting excitation and emission spectra toward the red and infrared enabled the imaging of blood flow in progressively deeper tissue. Using 633/825 microspheres, the authors recorded and tracked particles in the microcirculation of the choroid. CONCLUSION: The authors' findings suggest that fluorescent microsphere imaging provides images useful for studying the retinal circulation and for evaluating previously inaccessible choroidal hemodynamics.

Animals↗
PubMedDate not supplied

Microsphere uptake by the intestine of White Leghorn chickens.

A study was conducted to determine the effective size for latex microsphere uptake in the intestine of white leghorn chickens. Three trials were conducted in which ligated intestinal segments of anesthetized 8-wk-old chickens were injected with 0.2-, 0.5-, 2-, 6-, 10-, or 20-mu diameter fluoresceinated latex microspheres. Microspheres were counted in brush border, epithelium, and lamina propria of each intestinal segment, liver, and spleen. After 1 hr, the 0.2-, 0.5-, and 2-mu microspheres were oriented along the brush border of epithelial cells and microsphere uptake into the epithelium and lamina propria was observed in the duodenum, ileum, cecum, cecal tonsil, and colon. Uptake of microspheres of 6, 10, and 20 mu diameter into epithelium and lamina propria was not observed in any intestinal segment. Also, no microspheres of any diameter were observed in sections of liver and spleen to suggest that there was no appreciable entry of microspheres into the bloodstream within 1 hr after administration. The results indicated that uptake of microspheres by the chicken intestine is a size-dependent process with microspheres < or = 2 mu being taken up to an equal extent by most segments of intestine.

Animals↗
PubMed1998

pH and Ion-Triggered Volume Response of Anionic Hydrogel Microspheres.

Micrometer-sized (4-7 µm diameter) poly(methacrylic acid) (PMAA) hydrogel microspheres were synthesized by precipitation polymerization. Individual microspheres were held in a micropipet and visualized by interference contrast microscopy. They were characterized with regard to their mass, density, water content, electrophoretic mobility, and apparent pKa. Equilibrium changes in volume were measured as functions of the pH and NaCl concentration of the suspending solution. The maximum reduction in the microsphere equilibrium volume (Vrmax) at pH 3.0 was 0.28, where Vr was the ratio of the microsphere volume at the test pH to its volume at pH 6.6. A Donnan-based thermodynamic model, modified to include counterion binding because of the high fixed charge density in the microspheres (3.0 M), was applied to determine the difference in the ion concentration between the interior and exterior of the gel. The ion concentration differences (which were related to the osmotic pressure) predicted by the model were proportional to the microsphere equilibrium volume with changing pH and salt concentration. This supported the hypothesis that the equilibrium volume of the microspheres was set by a force balance between the osmotic pressure and the elasticity of the hydrogel matrix. Microspheres changed from their maximum equilibrium volume at pH 6.6 to their minimum equilibrium volume at pH 3.0 in 300 ms. This indicated that diffusion of the polymer matrix and not diffusion of ions into and out of the microsphere was the rate-limiting factor in determining a microsphere's swelling rate.

Journal Article↗
PubMed2000

Effects of 90Y-microspheres on liver tumors: comparison of intratumoral injection method and intra-arterial injection method.

UNLABELLED: Internal radiation therapy using intrahepatic arterial injection of 90Y-labeled glass microspheres (90Y-microspheres) has proven to be a promising therapeutic modality for inoperative liver tumor. Recently, direct intratumoral injection of 90Y-microspheres has been performed with even more encouraging results. The purpose of this study was to compare the treatment efficacy of these 2 methods using 90Y-microspheres. METHODS: Forty-eight male rats, each bearing a hepatic tumor, were divided into 4 groups (12 rats in each group) to evaluate the efficacy of treatment. Group 1 received an intratumoral injection of 37 MBq (1 mCi) 90Y-microspheres. Group 2 received an intratumoral injection of 0.1 mL normal saline as the control group. Group 3 received an intra-arterial injection of 37 MBq (1 mCi) 90Y-microspheres. Group 4 received an intra-arterial injection of 0.1 mL normal saline as the control group. Tumor size was measured by liver sonography before injection as well as at 2 and 4 wk after injection. Survival time was calculated from the day of treatment to 2 mo after treatment by Kaplan-Meier survival analysis. The response rate was evaluated by the change in tumor size and survival time. Fisher's exact, 2-tailed test was used to compare response rates. RESULTS: In the rats treated by intratumoral injection of 90-Y-microspheres, 83.3% (10/12) showed a good response. In contrast, all 12 rats in the control group showed a poor response. The difference was significant (P < 0.00001). Eighty-three percent (10/12) of the rats survived >60 d after intratumoral injection of 90Y-microspheres, whereas only 25% (3/12) of the control rats survived >60 d. The difference was significant (P = 0.0068). In the rats treated by intra-arterial injection of 90Y-microspheres, 58.3% (7/12) showed a good response to the treatment. All rats in the control group showed a poor response. The difference was significant (P = 0.0023). Sixty-six percent (8/12) of the rats survived >60 d after intra-arterial injection of 90Y-microspheres, whereas only 16.7% (2/12) of the control rats survived >60 d. The difference was significant (P = 0.0385). However, the response rate and survival time between the intratumoral treatment group and the intra-arterial treatment group showed no significant difference (P = 0.3707 and 0.3988, respectively). CONCLUSION: Both methods (intratumoral treatment and intraarterial treatment) showed a significantly good response rate and prolonged survival time compared with those of the control groups. However, no significant difference was found in the response rate or survival time between intratumoral treatment and intra-arterial treatment.

Animals↗
PubMed1985

Biodegradable mitomycin C microspheres given intra-arterially for inoperable hepatic cancer. With particular reference to a comparison with continuous infusion of mitomycin C and 5-fluorouracil.

Thirty-two patients with inoperable hepatic cancer underwent intra-arterial hepatic infusion using mitomycin C (MMC) and 5-fluorouracil (5-FU) or intra-arterial hepatic chemoembolization using heated albumin microspheres containing MMC with an average diameter 45 +/- 8 micron. Nineteen of the 32 patients received the MMC microsphere treatment and another 13 received the conventional infusion treatment, lasting for 3.4 months. The administered doses of MMC microspheres were 11.7 +/- 11.1 mg as MMC in the 12 with metastatic cancer and 6.9 +/- 2.1 mg as MMC in the 7 with hepatocellular cancer (HCC). On the contrary, the 13 patients who underwent conventional infusion had average doses of MMC 34.5 +/- 17.3 mg and of 5-FU 13.4 +/- 7.7 g, over 3.4 months. An objective tumor response was obtained in 13/19 (68.4%) under MMC microsphere chemoembolization, compared to 6/13 (46.2%) under the conventional infusion. The average level of CEA in the 12 with metastatic cancer, who underwent MMC microsphere therapy, dropped from 57.7 ng/ml to 16.5 ng/ml, while that in the 10 patients on conventional infusion dropped from 24.0 ng/ml to 17.4 ng/ml; that of alpha-fetoprotein dropped in all 7 with HCC on MMC microsphere chemoembolization, compared to a fall in 1/3 on conventional infusion. With the MMC microsphere treatment, 5 patients from colorectal cancer lived for 15.6 +/- 7.6 months, 2 are alive with a long life expectancy; and 7 patients from gastric or pancreatic cancer lived for only 9.3 +/- 3.3 months. In case of conventional infusion, 6 patients from colorectal cancer survived for 8.6 +/- 3.2 months; and 4 patients from gastric or gallbladder cancer survived for 6.0 +/- 1.0 months. The MMC microsphere treatment is superior at P = 0.059 in survival duration to the conventional infusion treatment. However, much the same survival occurred in 7 on MMC microsphere chemoembolization and 3 on continuous infusion.

Adult↗
PubMed1993

An experimental study and clinical pilot trials on yttrium-90 glass microspheres through the hepatic artery for treatment of primary liver cancer.

BACKGROUND: Yttrium-90 (90-Y) glass microsphere is a new kind of radiation microsphere for internal radiation therapy of primary liver cancer (PLC). The study was carried out by administration of 35 microns nondegradable 90-Y glass microsphere through the hepatic artery for treatment of PLC. METHODS: Six rabbits were injected with 185-1480 megabecquerels (MBq) of 90-Y glass microspheres, and three rabbits were injected with 35-300 mg of 89-Y glass microspheres for the toxic test. Eighteen patients received 2442-5550 MBq of 90-Y glass microspheres for the treatment of PLC. Whole blood counts, liver function, and imaging examination were performed. Pathologic examinations were performed on all rabbits. RESULTS: All rabbits were apparently well after absorbing 114.1-845.2 Gy 90-Y glass microspheres in the liver but showed transient degeneration of hepatocytes and portal fibrosis histologically. The mean absorbed dose in liver tissue of patients with PLC was 30.33 Gy, whereas that in tumor tissue was 88 Gy and the highest in tumor tissue, 186.36 Gy. The mean tumor:liver tissue ratio was 3:1; the highest, 14:1. Fourteen patients were still alive after half a year's follow-up and 6 of these 14 were still alive after 1 year. CONCLUSIONS: The rabbits could tolerate up to eight-fold of the upper limit of clinical dose (100 Gy). Good responses to the radiation therapy of 90-Y glass microspheres in patients with localized and hypervascular or vascular mass were achieved. Contraindications for the therapy were presence of massive hepatic arterioportal shunt and cancer emboli in the main portal vein. It is safe and applicable to deliver 90-Y glass microspheres in large doses through the hepatic artery for internal radiation treatment of PLC.

Adult↗
PubMed2005

Performance characteristics of a microsphere immunoassay using recombinant HCV proteins as a confirmatory assay for the detection of antibodies to the hepatitis C virus.

BACKGROUND: The detection of antibody to hepatitis C virus (HCV) is an important assay for the identification of individuals infected with this virus. However, the confirmation of antibody positivity remains problematic. Currently none of the screening or confirmatory assays provide quantitation of the antibodies present. A microsphere assay was designed to provide improved confirmation. METHODS: Microspheres of 3.6 mum in diameter coated with NeutraAvidin were used to capture biotinylated HCV recombinant proteins. A phycoerythrin goat anti-human immunoglobulin G (IgG) was used to detect specific antibody captured to the microsphere. A human IgG calibrator was designed that was internal to each sample in the microsphere assay. RESULTS: Detection of HCV-specific antibody using these microspheres was straightforward in most samples, with the lower detection limit set at 0.01 microg equivalents of human IgG per milliliter. In antibody-positive samples, the HCV antibody levels ranged from 0.09 to 55 microg equivalents of IgG per milliliter. Forty-nine of the 54 samples (91%) previously identified as having an indeterminate serologic pattern were negative in the microsphere assay. CONCLUSIONS: The microspheres and biotinylated HCV proteins were stable for longer than 8 months when stored at 2 degrees C to 8 degrees C and coating of the microspheres was reproducible with an interassay coefficient of variation less than 10%. Avidin-coated microspheres provide an easy solid support on which to design an assay provided the capture reagent being used can be biotinylated effectively. Confirmation of antibody to HCV can be performed using this assay format.

Flow Cytometry↗
PubMed2003

Preparation, characterization, and in vitro release of gentamicin from coralline hydroxyapatite-alginate composite microspheres.

In this work, composite microspheres were prepared from bioactive ceramics such as coralline hydroxyapatite [Ca(10)(PO(4))(6)(OH)(2)] granules, a biodegradable polymer, sodium alginate, and an antibiotic, gentamicin. Previously, we have shown a gentamicin release from coralline hydroxyapatite granules-chitosan composite microspheres. In the present investigation, we attempted to prepare composite microspheres containing coralline hydroxyapatite granules and sodium alginate by the dispersion polymerization technique with gentamicin incorporated by absorption method. The crystal structure of the composite microspheres was analyzed using X-ray powder diffractometer. Fourier transform infrared spectra clearly indicated the presence of per-acid of sodium alginate, phosphate, and hydroxyl groups in the composite microspheres. Scanning electron micrographs and optical micrographs showed that the composite microspheres were spherical in shape and porous in nature. The particle size of composite microspheres was analyzed, and the average size was found to be 15 microns. The thermal behavior of composite microspheres was studied using thermogravimetric analysis and differential scanning calorimetric analysis. The cumulative in vitro release profile of gentamicin from composite microspheres showed near zero order patterns.

Alginates↗
PubMed2004

Prolonged cytotoxic effect of colchicine released from biodegradable microspheres.

One the main problems of cancer chemotherapy is the unwanted damage to normal cells caused by the high toxicities of anticancer drugs. Any system of controlled drug delivery that would reduce the total amount of drug required, and thus reduce the side effects, would potentially help to improve chemotherapy. In this respect, biodegradable gelatin microspheres were prepared by water/oil emulsion polymerization and by crosslinking with glutaraldehyde (GTA) as the drug-carrier system. Microspheres were loaded with colchicine, a model antimitotic drug, which was frequently used as an antimitotic agent in cancer research involving cell cultures. Microsphere sizes, swelling and degradation properties, drug-release kinetics, and cytotoxities were studied. Swelling characteristics of microspheres changed upon changing GTA concentration. A decrease in swelling values was recorded as GTA crosslink density was increased. In vitro drug release in PBS (0.01M, pH 7.4) showed rapid colchicine release up to approximately 83% (at t = 92 h) for microspheres with low GTA (0.05% v/v), whereas a slower release profile (only approximately 39%) was obtained for microspheres with high GTA (0.50% v/v) content, for the same period. Cytotoxicity tests with MCF-7, HeLa and H-82 cancer cell lines showed that free colchicine was very toxic, showing an approximately 100% lethal effect in both HeLa and H-82 cell lines and more than 50% decrease in viability in MCF-7 cells in 4 days. Indeed, entrapped colchicine indicated similar initial high toxic effect on cell viability in MCF-7 cell line and this effect became more dominant as colchicine continued to be released from microspheres in the same period. In conclusion, the control of the release rate of colchicine from gelatin microspheres was achieved under in vitro conditions by gelatin through the alteration of crosslinking conditions. Indeed, the results suggested the potential application of gelatin microspheres crosslinked with GTA as a sustained drug-delivery system for anticancer drugs for local chemotherapy administrations.

Biocompatible Materials↗