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.

Detection of inflammatory lymph nodes in rabbits by 99mTc-HIG lymphoscintigraphy.

Tc-Human immunoglobulin G ( Tc-HIG) is a well-known radiopharmaceutical for the evaluation of inflammatory lesions. Recently, it has been demonstrated as a new agent for the visualization of the lymphatic system by our group. Our aim was to investigate the feasibility of detection of inflammatory lymph nodes by Tc-HIG lymphoscintigraphy. Ten adult New Zealand rabbits were used as group A. In a baseline study, 37 MBq Tc-HIG (0.1 ml) was injected into both hind legs of the rabbits, and sequential posterior gamma imaging with the rabbits lying prone was performed at 5, 15, 30, 60, 90 and 120 min using a single-headed gamma camera (Toshiba GCA G01 E). One week later, microorganisms ( ) were injected in a volume of 0.1 ml intradermally into the web space between the second and third toes in the bilateral hind legs of each rabbit in order to obtain inflammation in the popliteal lymph nodes. After 4 days, 37 MBq Tc-HIG (0.1 ml) was injected into the hind legs of the rabbits bilaterally, and sequential posterior gamma imaging was performed as described above (second study). Another group of 10 adult New Zealand rabbits (group B) was injected with the same microorganisms in the right hind legs only. After 4 days, scintigraphic imaging was carried out in the same way as described above (third study). Regions of interest were drawn over the injection sites and popliteal lymph nodes on each image for semiquantitative analysis. Count rates for each were calculated and a decay correction was applied. Time-activity curves were generated to show the percentage retention of radioactivity in each region. After the scintigraphic study, some of the group B rabbits were killed by intravenous injection of pentobarbitone (100-150 mg.kg, and both left and right lymph nodes were removed for microscopic examination. On the scintigrams, lymphatic channels and popliteal lymph nodes were visualized within 15 min. In the second study, bilateral popliteal lymph nodes were visualized more clearly than in the baseline study. The right popliteal lymph nodes of the rabbits were more clearly visualized in the third study. Semiquantitative analysis showed a higher percentage uptake of radioactivity in the right compared to the left popliteal lymph nodes in group B rabbits. Microscopic examination of the tissue sections demonstrated inflammation in the right lymph nodes of group B rabbits. In this preliminary study, it was found that Tc-HIG is a new promising agent for the demonstration and evaluation of inflammatory lymph nodes.

In vitro evaluation and intra-articular administration of biodegradable microspheres containing naproxen sodium.

The dispersion of non-steroidal antiinflammatory drugs (NSAIDs) into biodegradable polymeric matrices have been accepted as a good approach for obtaining a therapeutic effect in a predetermined period of time meanwhile minimizing the side effects of NSAIDs. In the present study, it was aimed to prepare Naproxen Sodium (NS), (a NSAID) loaded microsphere formulation using natural Bovine Serum Albumin (BSA) and synthetic biodegradable polymers such as poly(lactide-co-glycolic acid) (PLGA) (50:50 MW 34,000 and 88,000 Da) for intra-articular administration, and to study the retention of the drug at the site of injection in the knee joint. NS incorporated microspheres were evaluated in vitro for particle size (the mean particle size; for BSA microspheres, 10.0 +/- 0.3 microm, for PLGA microspheres, 9.0 +/- 0.2 and 5.0 +/- 0.1 microm for MW 34,000 and 88,000 Da, respectively), yield value, drug loading, surface morphology and drug release. For in vivo studies, monoarticular arthritis was induced in the left knee joints of rabbits by using ovalbumin and Freund's Complete Adjuvant as antigen and adjuvant. A certain time (4 days) is allowed for the formation of arthritis in the knee joints, then the NS loaded microspheres were injected directly into the articular cavity. At specific time points, gamma scintigrams were obtained to determine the residence time of the microspheres in knee joints, in order to determine the most suitable formulation. This study indicated that PLGA, a synthetic polymer, is more promising than the natural type BSA microspheres for an effective cure of mono-articular arthritis in rabbits.

Scintigraphic imaging of uveal melanoma with 99Tcm-glutathione.

A prospective study with a new tumour-seeking agent, 99Tcm-glutathione (GSH), was performed on 17 patients with choroidal melanoma. Planar and SPECT images using 99Tcm-GSH clearly demonstrated melanotic melanoma but failed to show amelonotic melanomas. Following confirmation of our results by concurrent ultrasonography and magnetic resonance imaging or computed tomography, patients were managed by either 125I plaque brachytherapy, diode laser transpupillary thermotherapy or enucleation depending on the site and location. In combination with other diagnostic tests, 99Tcm-GSH scintigraphy may play a role in the detection of uveal melanoma and its possible distant metastases.

Detection of head and neck cancer with 99Tc(m) glutathione: a correlative study with tissue glutathione and glutathione S-transferase levels.

In this study glutathione (GSH), a natural tripeptide which plays an important role in detoxification reactions, protecting cells against damage from xenobiotics, has been labelled with 99Tc(m) for the demonstration of head and neck cancer. Twenty-eight patients (10 females and 18 males) with various malignancies of the head and neck were given 740 MBq of 99Tc(m)-GSH intravenously and single-photon emission computed tomography (SPECT) images were obtained at 3 h. Semiquantification was performed by drawing regions of interest on three consecutive transaxial slices and tumour to background ratios were calculated. In addition, GSH and glutathione S-transferase (GST) levels were measured in the tumour samples and in normal tissue which were obtained during surgery. Scintigraphic images showed that there was increased uptake in the tumour compared to the normal contralateral side (tumour/normal tissue (mean +/- SD) = 1.94 +/- 0.76). The tissue analyses revealed increased levels of GST in tumour tissues, but both GST and GSH levels in tumour were not statistically different from those in the normal tissue. We conclude that scintigraphic visualization of head and neck tumours can be attributed to increased demand for GSH in cancer. Protein binding might account for the prolonged retention of 99Tc(m)-GSH in the malignant tissue. Like other peptides, it is accumulated and excreted by the kidneys, which allows clear visualization of the abdomen without interference from gastrointestinal system activity.

Microleakage study of various soft denture liners by autoradiography: effect of accelerated aging.

STATEMENT OF PROBLEM: The longevity of soft denture liners is a major clinical problem. Debonding of the soft liner from the denture base material is one of the factors that influence their longevity. Debonding of the soft liner can be attributed to microleakage at the interface. PURPOSE: This study investigated microleakage at the interface of various soft liners and base materials. MATERIALS AND METHOD: Six soft liners were investigated. Forty specimens of each material in disk form (10 mm in diameter, thickness of approximately 4 mm) were prepared. Twenty specimens of each material were stored in an accelerated weathering tester for 900 hours. For 2 days, all disks were immersed in (45)Ca radioisotope solution, then they were embedded in acrylic resin blocks and sectioned longitudinally. Autoradiographic imaging was used to determine microleakage at the interface of the soft liners and their bases. RESULTS: Significant differences between nonaged materials were found (P<.05).The difference between Molloplast B and Mucopren (silanized) was not significant (P<.05). Differences among aged materials were significant (P>.05). Differences between Mucopren (nonsilanized), Mucopren (silanized), and Ufigel P-Tokuyama were not significant (P<.05). Significantly decreased microleakage characteristics were determined for Molloplast B, Mucopren (nonsilanized) and Ufigel P liners after aging. CONCLUSION: Microleakage of Mucopren and Molloplast B lining materials was the lowest. However, the microleakage of Flexor and Simpa was the highest. The aging process did not significantly affect the microleakage characteristics of the Simpa, Flexor, Mucopren (silanized), or Tokuyama materials. Molloplast B, Mucopren (nonsilanized), and Ufigel P materials should significantly decrease microleakage properties after aging.

Biodistribution of 99mTc-glutathione in mice with osteosarcoma: effect of gamma irradiation on tumour uptake.

The aim of this study was to determine the efficacy of 99mTc-glutathione (GSH) in scintigraphic demonstration of osteosarcoma tumour in mice and the effect of gamma irradiation of tumour on tumour uptake of 99mTc-GSH. The biodistribution of 99mTc-GSH was studied in 30 Balb C mice 3 weeks after isotransplanting osteosarcoma OTS-64 in their thighs. The mice were injected with 400 microCi of 99mTc-GSH in 0.1 ml through the tail vein. They were equally divided into two groups. In the second group the tumours were subjected to gamma irradiation for 10 min (20 Gy). The mice in both groups were killed at 1, 3 and 6 h. Scintigrams were obtained at each time point. The organs, tumours, some muscle and some blood were removed, weighed and assayed for radioactivity. Tumour, liver and muscle sections were also obtained for gross autoradiographic studies. The tumours were well visualized on scintigrams. The tumour uptake values as a function of time after injection were 3.27+/-0.80, 1.53+/-0.69, and 1.51+/-0.55 for the control and 5.18+/-1.28, 0.399+/-0.120, and 1.67+/-1.05%/g for the irradiated groups at 1, 3 and 6 h, respectively. The tumor-to-muscle concentration ratios were 34.03+/-12.2, 21.4+/-11.3 and 18.7+/-11.4 for the control and 18.8+/-7.2, 3.63+/-1.9, and 24.1+/-9.0 for the irradiated groups, respectively. The gross autoradiographic images of tumour sections indicated focal sites of increased uptake within tumour tissue, indicating the presence of necrotic areas. In conclusion, 99mTc-GSH accumulated in osteosarcoma and resulted in high tumour-to-other tissue concentration ratios in mice. The increase in uptake values after tumour irradiation might be a result of increased demand of tumour cells for GSH attributable to its well-known biological function as a reducing agent in addition to increased blood flow and capillary permeability in malignant tissues.

Therapeutic radiopharmaceuticals.

A variety of radiopharmaceuticals have been introduced for the internal therapy of malignant and inflammatory lesions in nuclear medicine. In order to destroy the diseased tissues radionuclides with high linear energy transfer (LET) such as beta, alpha, Auger or low energy conversion electron emitters are needed. The range of beta particles is in mm's so they are effective for large tumors. The range of alpha particles is short, only a few cell diameters. Thus, they are effective in treating circulating malignant cells and micrometastases. The range of Auger and conversion electrons is <0.1 micro m. They are very effective in cell killing when they are carried across cell membrane into the nucleus to damage DNA. Appropriate ions, molecules and particles are labelled with such radionuclides and used as radiopharmaceuticals in many different applications. For an effective dose to be delivered high target to non target ratios must be attained. Monoclonal antibodies to specific antigens expressed on tumor cells have been developed to increase the uptake by malignant tissues by specific accumulation. Radiolabelled peptides such as somatostatin, small molecules such as metaiodo-benzylguanidine (MIBG) and many different nano-and micro-particles have been investigated. The effectiveness of therapy can be increased by direct locoregional administration of the radiopharmaceutical. This way the radiation effects are confined locally and the normal tissues are spared from radiation effects. In this review article selection criteria and characteristics of radionuclides and carrier ions, molecules and particles for various therapeutic applications will be discussed, including mainly the recent developments.

Radiopharmaceuticals for the visualization of infectious and inflammatory lesions.

Many radiopharmaceuticals have been introduced for the scintigraphic demonstration of infectious and inflammatory lesions and some of them are currently in clinical use. They can be classified into two major categories according to their specificity. Specific radiopharmaceuticals include in vitro labeled leukocytes, radio-labelled monoclonal antibodies, and receptor specific small proteins and peptides. Nonspecific radiopharmaceuticals include radiolabelled nanocolloids, liposomes, macromolecules such as human immunoglobulin, dextran and human serum albumin, various small molecules and ions. In this review article radiopharmaceuticals in their respective groups are discussed as to the efficacy, and other parameters such as the physical characteristics of the radionuclides used, radiochemistry involved, availability, cost and biodistribution, emphasizing recent developments.

Evaluation of 99mTc labelled poly lactic acid microspheres for diagnostic radioembolization.

Radioembolization is used in diagnostic imaging of the lungs and for radioembolization therapy of hepatic tumours. Presently, 99mTc labelled macroaggregates or microspheres of human serum albumin (HAM) are used for this purpose. Poly lactic acid (PLA) is biodegradable, like HAM, and, unlike HAM, is not a blood product. The aim of the present study was to evaluate the uptake and biodegradation of PLA microspheres in lungs. PLA (MW = 48720 Da) microspheres of 1.0-100 microm (mean = 39.5 microm) in diameter were prepared by solvent evaporation from methylene chloride. They were labelled with 99mTc by stannous chloride reduction at pH 3, with an efficiency of 98% and a stability of 96% at 24 h. For biodistribution studies, 15 mice were i.v. injected with 20 microCi 99mTc-PLA microspheres in 0.1 ml and sacrificed at 15 min, 1, 3, 6 and 24 h (three at each time point). All the organs were removed, weighed and counted against a standard prepared from 1/100 dilution of the injected radioactivity. Some mice were similarly injected and sacrificed at 30 min, 15 and 30 days. The lungs were removed and frozen, and 10 microm sections were obtained, stained with haemotoxylin and eosin and examined under a light microscope. Five rabbits were i.v. injected with 1 mCi of 99mTc-PLA microspheres. Scintigrams were obtained at various intervals up to 24 h. In mice, the lung uptake was significant at 30 min-1h post-injection. In rabbits, the lungs were the only organs visualized up to 24 h. Microscopic examination of tissue sections demonstrated slow biodegradation of PLA particles. In conclusion; (1) The high lung uptake obtained in mice and rabbits indicates the suitability of PLA microspheres for lung imaging, and (2) although the slow biodegradation rate might be a disadvantage in patients with lung disorders in diagnostic studies, it may be an advantage in therapeutic applications with radionuclides which have long physical half lives.

Scintigraphic imaging of infections with 99m-Tc-labelled glutathione liposomes.

In this study, liposomes containing glutathione were evaluated to detect infection in mice. Glutathione liposomes were labelled by using 99mTc-labelled-HMPAO (hexamethyl propylamine oxime). Mice were infected in the thigh by intramuscular injection with turbentine. Labelled liposomes were applied to the tail vein of the mice intravenously. At fixed time intervals they were sacrificed. The animals were imaged under a gamma camera. Then, tissue samples were excised and radioactivity of all organs was counted. Abscess-to-muscle, abscess-to-liver, and abscess-to-spleen ratios were calculated. The ratios of abscess-to-muscle were found to be 1.6 and 11.6 at 1 h and 24 h, respectively. According to these data, the abscess can be defined at 1 h and it became more clear with time.

In vitro and in vivo evaluation of diclofenac sodium loaded albumin microspheres.

The use of polymeric carriers in formulations of therapeutic drug delivery systems has gained widespread application, due to their advantage of being biodegradable and biocompatible. Among the microparticulate systems, microspheres have a special importance since it is possible to target drugs and provide controlled release. Diclofenac sodium (DS), is a potent drug in the NSAID group having non-steroidal, anti-inflammatory properties, and is widely used in the treatment of rheumatoid arthritis, osteoarthritis and ankylosing spondylitis. In this present study, it was aimed to prepare microsphere formulations of DS using a natural biodegradable polymer as a carrier for intraarticular administration to extend the duration period of the dosage form in the knee joint. Microsphere formulations of DS which were prepared were evaluated in vitro for particle size, yield value, encapsulation efficiency, surface morphology, and in vitro drug release. Two appropriate formulations were selected for in vivo trials. For the in vivo studies, Technetium-99m labelled polyclonal human immunogammaglobulin (99mTc-HIG) was used as the radiopharmaceutical to demonstrate arthritic lesions by gamma scintigraphy. After the induction of arthritis in knee joints of rabbits, the radio-labelled microspheres loaded with DS were injected directly into the articular cavity and at specific time points gamma scintigrams were obtained to find the residence time of the microspheres in knee joints in order to determine the most suitable formulation.

Diclofenac sodium incorporated PLGA (50:50) microspheres: formulation considerations and in vitro/in vivo evaluation.

Recently, considerable interest has been focused on the use of biodegradable polymers for specialized applications such as controlled release of drug formulations; meanwhile, microsphere drug-delivery systems using various kinds of biodegradable polymers have been studied extensively during the past two decades. Poly (lactide-co-glycolide) (PLGA) polymers have been proven to be excellent drug carriers for microparticulate systems due to their advantages, e.g. biocompatibility and regulatory approval. The administration of nonsteroidal anti-inflammatory drugs (NSAIDs) into the intra-articular cavity in patients with chronic inflammatory disease is complicated due to the short duration of effect. In the present study, controlled-release parenteral formulations of diclofenac sodium (DS), a commonly used NSAID, were prepared for intra-articular administration, and evaluated in vitro for particle size, yield, drug loading, surface morphology and release characteristics. For in vivo studies, Technetium-99m labelled polyclonal human immunogammaglobulin (99m Tc-HIG) was used as the radiopharmaceutical to demonstrate arthritic lesions by gamma scintigraphy. Evaluation of arthritic lesions post-therapy in rabbits showed no significant difference in the group treated with PLGA (50:50) (mw 34000) DS microspheres compared to control groups.

Tc-Glutathione Complex (Tc -GSH) : Labelling, Chemical Characterization and Biodistribution in Rats.

The chemical structure of (99m)Tc-GSH has been estabilished using the (99)Tc isotope. Labeling of glutathione with technetium in the presence of stanous chloride gave a high yield result. In a comparative study between (99)Tc and (99)Tc glutathione, the Tc-GSH complex obtained was purified and characterized by uv, visible spectroscopy, HPLC, Biogel chromatography, mass and NMR spectroscopy. Stoichiometric analysis showed a 2 : 1 molar ratio of GSH/Tc for the reaction. The molecular mass assessed by mass spectroscopy was 727 Da corresponding to an oxo(bis) glutathione technetate. NMR studies demonstrated that each glutathione molecule was coordinated to technetium via cysteinyl sulfur and nitrogen atoms. The biodistribution of the complex was studied in normal rats. Blood clearance was rapid during the first hour involving a biexponential curve ( t1/2 (1) : 50 min, t1/2 (2) : 400 min ). No radioactive accumulation was found in any specific organ except kidney and bladder. All the activity excreted was found unchanged in urine. In conclusion, Tc-GSH displayed an anionic dimer form as GSH-Tc-GSH. We assume that the complex is a tetradentate (2N,2S) complex containing a pentavalent technetium coordinated by two thiol and nitrogen atoms of both GSH ligands, and an apical oxo group.

Evaluation of 99Tcm-HIG as a lymphoscintigraphic agent in rabbits.

In this pilot study, 99Tcm-labelled human immunoglobulin G (99Tcm-HIG) was evaluated as a lymphoscintigraphic agent in five rabbits. It was injected intradermally into the web space of the hind legs of the rabbits (37 MBq/0.1 ml). Sequential scintigrams were obtained using a gamma camera for 120 min. The injection site and the hind legs were massaged post-injection. Blood samples were obtained at 5, 15, 30, 60, 90 and 120 min. Two of the rabbits were killed after 2 h. Their organs were weighed and tissue specimens were obtained, weighed and counted against a standard using a gamma counter. The lymph channels and the lymph nodes were well visualized on the scintigrams. The background activity was very low, making interpretation easier. About 30% of the injected dose migrated from the injection site by 2 h. The mean popliteal lymph node uptake was 5.71 +/- 4.62% per gram of tissue. The lymph node to other tissue concentration ratios were very high, ranging from 63:1 for the kidneys to 1099:1 for the heart. We conclude that 99Tcm-HIG is a promising new agent for the visualization of the lymphatic system due to its easy labelling procedure, the stability of the label, its widespread availability and good image quality. It may potentially be useful in detecting and evaluating inflammatory lymph nodes.

Technetium-99m (V) dimercaptosuccinic acid uptake by choroidal melanoma before and after iodine-125 brachytherapy.

PURPOSE: The value of the new tumour-seeking agent technetium-99m (V) dimercaptosuccinic acid (99mTc (V) DMSA), is assessed by the visualization of choroidal melanoma before and after iodine-125 episcleral plaque brachytherapy. METHODS: A prospective study was conducted on 12 consecutive patients with choroidal melanoma that was to be treated with plaque brachytherapy. The pre-operative mean (+/- SD) maximal tumour basal diameter was 12.9+/-2.9 mm and the mean tumour height was 8.2+/-2.9 mm. Each patient had planar scintigraphy and single-photon emission computed tomography using 99mTc (V) DMSA 2 days before treatment and 8 months following plaque removal. The calculated tumour to background ratios of these two tests were compared. RESULTS: The pre-operative tumour to background ratio was 1.8+/-0.4 and all tumours could be correctly identified. At the time of postoperative imaging, all melanomas showed varying degrees of regression. The mean tumour height was 4.4+/-2.1 mm. The tumour to background ratio was 1.4+/-0.3. The difference between the two scintigraphic results was statistically significant (P = 0.002). CONCLUSIONS: Technetium-99m (V) DMSA scintigraphy can accurately detect choroidal melanoma and document tumour response following episcleral radioactive plaque therapy. As such, this test can be an alternative ancillary investigative tool in the rare event of opaque media or diagnostic uncertainty.

Visualization of orbital retinoblastoma with technetium-99m (V) dimercaptosuccinic acid.

The potential contributions of technetium-99m (V) dimercaptosuccinic acid scintigraphy in the evaluation of orbital retinoblastoma, its local extensions and metastases were assessed in this study. Both planar and SPECT images clearly demonstrated the primary tumor and metastatic sites. Following confirmation of our results by contemporaneous ultrasonography, MRI and a subsequent incisional biopsy, the patient was treated with external beam radiotherapy and chemotherapy. This preliminary study showed that in combination with other diagnostic tests, Tc-99m (V) DMSA scintigraphy may play a role in the detection and follow-up of the local tumor extensions and metastases in patients with retinoblastoma.

Scintigraphic evaluation of tumors metastatic to the choroid using technetium-99m(V)-dimercaptosuccinic acid.

Technetium-99m(V)-dimercaptosuccinic acid scintigraphy was used to evaluate three patients with intraocular tumors who had metastatic breast, lung, and rectal carcinomas, respectively. At the time of initial examination, two patients had no known systemic cancer, but the scintigraphy results in one patient revealed the primary site and were highly suggestive of disseminated carcinomatosis in the other patient. In the third patient, scintigraphy was successful to confirm very small bilateral intraocular tumors and also other systemic lesions. Technetium-99m(V)-dimercaptosuccinic acid scintigraphy can be reliably employed in a very select group of patients with intraocular tumors where metastatic carcinoma is a serious diagnostic possibility against a primary intraocular malignancy. This safe and promising tumor-imaging agent has the ability to demonstrate the ocular lesions and other systemic foci simultaneously, information that would prove to be crucial in both the diagnosis and the management of the patient.

Autoradiographic determination of marginal leakage of a pressed glass ceramic inlay.

The marginal integrity and microleakage of pressed glass ceramic inlays were evaluated using autoradiography. IPS/Empress ceramic inlays were fabricated for 10 human molar mandibular teeth. After adjusting the inlays, they were etched with 37% phosphoric acid gel for 30 s and silanized with Monobond S for 30 s. Before cementation with dual cure resin cement the inlays and cavity walls were gently covered with a thin layer of bonding agent. When the cementation process was completed the samples were cycled 300 times between a 55 degrees C hot bath and a 5 degrees C cold bath. The samples were placed in each bath for 60 s, with 5 s intervals between immersions, then the specimens were immersed in an aqueous solution of Ca-45. After 24 h the inlay and tooth assemblies were removed, rinsed with water and placed in cold-cured acrylic resin, then sectioned through the long axis for autoradiographic analysis. According to the penetration of Ca-45, the microleakage level was scored for each section. The results indicated slight penetration of Ca-45 on autoradiographic films.

Measurement of blood flow by the 133Xe clearance technique to grafts of amnion used in vestibuloplasty.

The purpose of this study was to determine the blood supply to lyophilized amniotic membranes when used as graft material in vestibuloplasties. 133Xe clearance technique was used to measure the blood flow to the grafts. A total of 20 patients had either Clark (10) or Kazanjian (10) vestibuloplasties. The blood flow was determined at 2-3 days preoperatively and at 10 and 30 days postoperatively. The preoperative mandibular anterior alveolar mucosal blood flow was 34.4 +/- 10.7 and 23.1 +/- 13.1 ml/100 g/min for the Clark and Kazanjian groups, respectively. Ten days after vestibuloplasty operation with lyophilized amniotic membrane graft application the blood flow to the graft increased to 56.8 +/- 45.4 and 62.6 +/- 30.4 ml/100 g/min for the Clark and Kazanjian groups, respectively. The corresponding values at 30 days postoperatively were 24.6 +/- 10.2 and 22.2 +/- 9.2 ml/100 g/min, indicating the return to normal levels. The changes in blood flow as a function of time were statistically significant in each group (P<0.05). Our results demonstrated the angiogenic effect of lyophilized amniotic membranes until mucoid degeneration after 10-15 days.