Biomedical subjects

M T Ercan

Publications and source records attributed to M T Ercan.

79 records · Page 5Linked to original sources

PubMedDate not supplied

Streptomycin sulphate microspheres: formulation and in vivo distribution.

Albumin and gelatin microspheres of streptomycin sulphate were formulated and their potential as a drug delivery system for a tuberculostatic agent in vivo was evaluated. Biodistribution was determined by i.v. administration of a 99mTc-labelled microsphere suspension to mice. The radioactivity of the lungs was compared with the radioactivity of the liver, spleen, kidney and heart at 10 min, 60 min, 4 h and 24 h post-injection. The percentage accumulated was higher in the lungs than in the other organs for both albumin and gelatin microspheres.

Albumins↗

PubMedDate not supplied

99mTc-labelled monodisperse latex particles coated with amino or carboxyl groups for studies of GI function.

Latex particles coated with either amino or carboxyl groups were labelled with 99mTc. Two labelling methods were used: (1) direct labelling with tin reduction and (2) ligand exchange with tin pyrophosphate. Labelling efficiency and the radiochemical impurities were determined by thin-layer chromatography. Effect of [Sn2+] and pH on labelling yield was investigated to find the optimum labelling conditions. 99mTc-labelled latexes were administered orally to six normal subjects, and scintigrams from the abdomen were obtained at 1, 3, 6, and 24 h. Whole-body scintigrams were also taken by a gamma-camera. The first method was found to be efficient for carboxyl coated latexes and the second method for both types, giving > 98 per cent labelling efficiency. Labelled latexes were stable up to 24 h of testing at RT (> 99 per cent labelled). Scintigraphic studies showed that the labelled particles remained in GIT (98.11 +/- 0.92 per cent at 6 h) without dissociation of the label. No radioactivity was observed in the thyroid, stomach (at late images) and urinary bladder. This study demonstrated that latex particles coated with either amino or carboxyl groups can be efficiently labelled with 99mTc and used in the studies of GI function.

Acrylates↗

PubMedDate not supplied

Characterization, in vitro and in vivo studies on primaquine diphosphate liposomes.

In this study, several Primaquine diphosphate (PQ) liposomal formulations containing phospholipid, charge inducer and with or without cholesterol in molar ratios of 7:1:(2) and 10:1:(4) were investigated. Gel state (DPPC:CHEMS:CHOL and PL-100H:CHEMS:CHOL) and liquid-crystalline state (PL-100:CHEMS:CHOL and PL-90G:CHEMS:CHOL) liposomes were prepared. The film method followed by sonication and extrusion through polycarbonate membrane was used. Particle size distribution, percentage of entrapped active substance, content of phospholipid and bilayer type and composition were determined. Lamellarity was determined by 31P-NMR technique. In vitro release of PQ was investigated at 37 degrees C, 35 rpm and in Tris (pH: 7.4) buffer. In vitro release and its fit to kinetic models were investigated. Liposomes were labelled by 99mTc and injected intravenously to Swiss Albino mice.

Animals↗

PubMedDate not supplied

In-vivo studies on dexamethasone sodium phosphate liposomes.

Dexamethasone Sodium Phosphate (DSP) is a water soluble anti-inflammatory steroid commonly used in the therapy of serious types of ophthalmic inflammation. It has been demonstrated that unless the corneal epithelium is damaged, DSP is poorly absorbed by the cornea (Kupferman et al. 1974). Thus, it is doubtful whether such a drug would cure inflammation of the anterior segments. For this purpose, several liposomal DSP formulations containing phospholipid: charge inducer: cholesterol in molar ratios of 10:1:4 were investigated. Both gel state (PL 90H: SA: Cho1) and liquid state (PL 100: SA: Cho1) liposomes were prepared. For the preparation of liposomes, the film method followed by bath sonication was used. Liposomes were labelled with (99m)-Tc and administered intra-ocularly to New Zealand white rabbits weighing 2.5-3 kg for in vivo experiments. The biodistribution of the labelled liposomes were determined. For this purpose, eye segments (such as cornea, lens, iris, ciliar body, vitreous, aqueous humor, conjuctiva and sclera) and RES organs (such as liver, pancreas, spleen) were removed at fixed time intervals. In the present study, the efficiency of liposomes for the delivery of water-soluble drugs was evaluated in rabbit eyes using DSP as a model drug in different liposomal formulations.

Amines↗

PubMedDate not supplied

In-vivo studies in the treatment of oral ulcers with liposomal dexamethasone sodium phosphate.

Liposomes are man-made organelles composed of bimolecular lipid layers enclosing aqueous compartments. Dexamethasone Sodium Phosphate (DSP) was encapsulated in MLV liposomes and served as the test solution. DSP in solution served as control. Both were labeled with 99mTc. The rats were divided into three groups: typical application group, intramucosal injection and control group. Oral mucosal ulcers were produced by silver nitrate and was monofocal. Rats were killed at three and 24 h, respectively, after application. Ulcerated mucosa, intact adjacent mucosa and distant mucosa were excised. Biodistribution was determined by radiotracer technique in the three mucosal parts as well as in the blood, liver, spleen and brain. Liposomes increase local and decrease systemic drug concentration. Another finding was that liposomes localize the drug in the ulcerated area. In conclusion, liposomes may be useful in the treatment of oral ulcers.

Administration, Topical↗

PubMedDate not supplied

Formulation and in vitro/in vivo evaluation of terbutaline sulphate incorporated in PLGA (25/75) and L-PLA microspheres.

Terbutaline sulphate (TBS) is widely used in the treatment of bronchial asthma, chronic bronchitis and emphysema. Because of its short biological half life and dosing schedule, a long acting TBS formulation is required to improve patient compliance. The objective of this study was to develop a TBS containing biodegradable microsphere formulation. Poly(D,L-lactide-co-glycolide) (PLGA) and poly(L-lactic acid) (L-PLA) were chosen as matrix materials. A solvent evaporation method was used for preparation of microspheres. Surface morphology, particle size distribution and encapsulation efficiency were investigated. In vitro release studies were performed in pH 7.4 phosphate buffer. In vitro distribution of microspheres were studied in the Swiss albino male mice. All microspheres were spherical in shape and had a porous surface with mean diameters of 9-21 microm. The encapsulation efficiency was influenced by the polymer type, but not the molecular weight. About 90% of the initial amount was trapped in PLGA microspheres, and the remainder was on the surface. In the case of L-PLA, 50% of the total drug was associated with the surface of microspheres. The In vitro release pattern was biphasic characterized by an initial burst phase followed by a slower phase. The L-PLA microspheres released approximately 92% of the initial payload in 72 h. On the other hand, TBS release was increased with an increase in the molecular weight of PLGA. Biodistribution of L-PLA microspheres was characterized by an initially high uptake (35%) by the lungs. All these results suggest that L-PLA and PLGA microspheres have the potential to be used for passive lung targeting.

Biodegradation, Environmental↗

PubMedDate not supplied

Investigation of the effect of magnetic retention systems used in prostheses on buccal mucosal blood flow.

The purpose of this study was to investigate the probable effects of the magnetic field produced by dental magnets on neighboring capillary circulation. Ten subjects were used. Transparent acrylic resin devices were prepared to receive the dental magnets and were used continually by subjects except during sleep. The maxillary buccal mucosal blood flow was measured on both sides (control and experimental) in the same subjects before the use of dental magnets and after 3, 7, 15, 30, and 45 days by the 133Xe clearance technique. Upon analysis it was found that the difference in blood flow between the control and experimental sides was insignificant (P greater than .05). The decrease in blood flow as time progressed was attributed to the pressure exerted by the oral devices rather than by the effect of the magnetic field.

Adolescent↗