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Biomedical subjects

I S Moon

Publications and source records attributed to I S Moon.

At least 37 records · Page 2Linked to original sources
PubMed1999

Peri-implant tissues at submerged and non-submerged titanium implants.

The present experiment was performed to study the peri-implant tissue response to non-submerged (1-stage) and initially submerged (2-stage) implant installation procedures. 6 beagle dogs were used. All mandibular premolars and the 1st, 2nd and 3rd maxillary premolars were extracted. After 3 months of healing, 3 fixtures of the Astra Tech System were installed and submerged in the right (or the left) edentulous, premolar region in each of the 6 dogs. Radiographs were obtained immediately after fixture installation. In the radiographs, the distance between the abutment-fixture junction and the most "coronal" bone in contact with the implant surface was determined. 3 months later, abutments were connected to the initially submerged fixtures and another 3 fixtures of the same system were installed in the contralateral, edentulous premolar region. Abutments were, however, immediately connected to the newly-installed fixtures (non-submerged side; test side). The mucosal flaps were replaced, adjusted and sutured in such a way that the coronal portion of the abutments remained exposed in the oral cavity. A new set of radiographs were obtained from all 6 implant sites in each animal. A period of plaque control was initiated. Clinical examinations were performed and radiographs obtained from all implant sites after another 3 months and at the termination of the experiment. 9 months after the 1st fixture installation procedure, the animals were sacrificed, the mandibles were removed, and each implant region dissected. The most mesially-located implant sites were processed for ground sectioning. The remaining biopsies were processed and embedded in EPON. The histometric analysis included assessment of the vertical dimension of the marginal soft and mineralized peri-implant tissues. The ground sections were used for measurements describing (i) "bone to implant contact" and (ii) "bone density". It was observed that the mucosa and bone tissue that formed at implants placed in a non-submerged or a submerged procedure had many features in common. Thus, figures describing (i) the height of the mucosa, (ii) the length of the junctional epithelium and the height and quality of the zone of "connective tissue integration", (iii) the % of bone to implant contact as well as (iv) the density of the peri-implant bone, were similar in the submerged and the non-submerged groups. It is therefore suggested that a non-submerged (1-stage) installation technique may provide conditions for tissue integration that are similar to those obtained using a submerged (2-stage) approach.

Alveolar Process↗
PubMed1999

The barrier between the keratinized mucosa and the dental implant. An experimental study in the dog.

The present study was performed in order to examine the composition of the connective tissue that forms an attachment to a dental implant. 6 beagle dogs were used. All mandibular premolars were extracted. After 3 months of healing, 6 fixtures--3 in each side of the mandible--(Astra Tech Implants, Dental System TiO blast; Astra Tech AB, Mölndal, Sweden) were installed. After another 3 months of healing, abutment (Uni-abutment 45; Astra Tech AB, Mölndal, Sweden) connection was performed and a plaque control program was initiated. The animals were sacrificed and perfused with a fixative through the carotid arteries. Each implant site, including the implant and the soft and hard peri-implant tissues, was dissected, decalcified in EDTA and further processed using a "fracture technique". The specimens were subsequently embedded in EPON, cut with the microtome set at 3 microm and the sections stained in PAS and toluidine blue. From the EPON-embedded blocks, ultra-thin sections were cut and electron micrographs were prepared. The detailed histologic and morphometrical examinations were restricted to a 200 microm wide zone of connective tissue interposed between the apical border of the junctional epithelium and the bone tissue. In the analysis, this zone was further subdivided into 2 different units; (i) one central, 40 microm wide unit (zone A) located immediately next to the implant surface, and (ii) one lateral, 160 microm wide unit (zone B) that was continuous with the central unit. The implant surface apical of the junctional epithelium and coronal of the bone crest appeared to be in direct contact with a connective tissue. Zone A of this connective tissue was characterized by its (i) absence of blood vessels and (ii) abundance of fibroblasts which were interposed between thin collagen fibers. The more lateral zone B contained comparatively fewer fibroblasts, but more collagen fibers and blood vessels. There are reasons to assume that the fibroblast rich barrier tissue next to the titanium surface plays a rôle in the maintenance of a proper seal between the oral environment and the peri-implant bone.

Alveolar Process↗
PubMed1998

Identification of glyceraldehyde-3-phosphate dehydrogenase by protein sequencing in the rat postsynaptic density fraction.

Although many abundant proteins of the postsynaptic density (PSD) are known, most of the less abundant and minor PSD proteins await identification. In this work we attempted to identify a 37 kDa protein, which represented less than 1% of the total n-octyl glucoside (NOG)-insoluble proteins, by protein sequencing. To enrich the target protein, the NOG-insoluble fraction was first electrophoresed in 6% SDS-polyacrylamide gels, and the proteins smaller than 45 kDa compressed in the gel from were electroeluted and subsequently reseparated in 10% SDS-gels. This procedure enriched the target protein to represent about 25% of the eluted proteins. Peptides were generated by digesting the target protein with trypsin directly in the gel and purified by a reverse phase high performance liquid chromatography (HPLC). Two peptides were determined for amino acid sequences. A database search revealed that both sequence were found in glyceraldehyde-3-phosphate dehydrogenase (GAPDH) with a minor discrepancy, indicating the the 37 kDa protein in the NOG-insoluble pSD fraction is an isoform of GAPDH.

Amino Acid Sequence↗
PubMed1998

Clinical course of cytomegalovirus (CMV) viremia with and without ganciclovir treatment in CMV-seropositive kidney transplant recipients. Longitudinal follow-up of CMV pp65 antigenemia assay.

This study was designed to evaluate the longitudinal history of cytomegalovirus (CMV) infection and to test the capacity of ganciclovir as effective therapy in CMV-seropositive renal transplant recipients. The CMV viremia was detected with CMV pp65 antigenemia assay in 153 renal transplants. The recipients were classified as having low-grade and high-grade CMV infections according to the severity of CMV infection. The recipients with low-grade CMV infections were observed without ganciclovir treatment, and the recipients with high-grade CMV infection were randomly assigned to ganciclovir-treated and untreated groups. The clinical course between low-grade and high-grade CMV infections was evaluated. All recipients with low-grade CMV infection (n = 62) showed spontaneous remission regardless of immunosuppresants. In high-grade CMV infection (n = 31), the ciclosporin A treated group (n = 11) showed no evidence of CMV disease, and the methylprednisolone-treated group (n = 8) showed CMV disease in 1 (25%) of 4 ganciclovir-untreated recipients. In the OKT3 group (n = 12), symptomatic CMV infection was observed in 6 (100%) ganciclovir-untreated recipients contrary to no CMV disease in the ganciclovir-treated group (p < 0.05). In conclusion, the CMV antigenemia assay is effective in monitoring CMV viremia, and ganciclovir treatment should be done during early CMV viremia in OKT3-treated recipients.

Adult↗
PubMed1998

Periodontal repair in intrabony defects treated with a calcium sulfate implant and calcium sulfate barrier.

THIS RANDOMIZED, CONTROLLED, CLINICAL STUDY was designed to evaluate outcome following surgical implantation of an allogeneic, freeze-dried, demineralized bone matrix-calcium sulfate (DBM+CS) composite with a CS barrier in intrabony periodontal defects. Twenty-six patients contributing 26 deep intrabony defects completed the study. Thirteen patients received the DBM+CS implant. Thirteen patients received gingival flap surgery alone (GFS; control). Clinical outcome was assessed at 6 and 12 months postsurgery. At 12 months postsurgery, probing depth (PD) reduction (mean +/-SD) for the DBM+CS and GFS group was to 4.3+/-0.5 and 3.0+/-1.3 mm; clinical attachment gain was to 2.9+/-0.8 and 1.7+/-1.5 mm; and probing bone level gain was to 2.9+/-1.4 and 1.2+/-1.2 mm, respectively. There were no apparent differences between evaluations at 6 and 12 months postsurgery. Clinical improvements were significantly different from presurgery for both groups at both observation intervals (P < 0.01). There were no significant differences between groups in PD reduction and clinical attachment gain. Probing bone level gain was significantly greater in the DBM+CS group compared to controls (P < 0.05). In summary, surgical implantation of DBM+CS with a CS barrier resulted in reduced PD and improved attachment levels comparable to that achieved by gingival flap surgery alone. However, gain in probing bone levels in deep intrabony periodontal pockets assessed by clinical parameters was greater than that observed by gingival flap surgery alone. These changes were noted at both 6 and 12 months after surgery. This regenerative technique needs further biologic evaluation before being generally accepted.

Adult↗
PubMed1998

Effect of a calcium sulfate implant with calcium sulfate barrier on periodontal healing in 3-wall intrabony defects in dogs.

This controlled, split-mouth, preclinical study was designed to evaluate outcome following surgical implantation of an allogeneic, freeze-dried demineralized bone matrix-calcium sulfate (DBM+CS) composite with a CS barrier in 3-wall intrabony periodontal defects in 4 dogs. Control conditions included surgical implantation of DBM or CS and gingival flap surgery (GFS) alone. Three-wall intrabony defects (4x4x4 mm) were surgically created at the mesial and distal aspect of the maxillary and mandibular first and third premolars, respectively. Maxillary and mandibular defects each received 1 of the 4 experimental conditions. Experimental conditions were rotated between defect sites in subsequent animals. Block sections of the defects were collected at sacrifice 8 weeks postsurgery and processed for histometric analysis. Histometric defect height (means +/- SD) for the DBM+CS, DBM, CS, and GFS groups amounted to 4.2 +/- 0.5, 4.3 +/- 0.7, 4.0 +/- 0.2, and 4.1 +/- 0.2 mm, respectively. Connective tissue adhesion (connective tissue contact to the root without apparent cementum formation) amounted to 0.4 +/- 0.3, 0.4 +/- 0.3, 0.5 +/- 0.2, and 1.6 +/- 0.5 mm for the DBM+CS, DBM, CS, and GFS groups, respectively; the DBM+CS, DBM, and CS groups being significantly different from the GFS group (P < 0.05). Cementum regeneration amounted to 3.0 +/- 0.3, 3.1 +/- 0.4, 2.5 +/- 0.4, and 1.6 +/- 0.3 mm for the DBM+CS, DBM, CS, and GFS groups, respectively; the DBM+CS, DBM, and CS groups being significantly different from the GFS group (P < 0.05). Alveolar bone regeneration amounted to 2.7 +/- 0.4, 2.7 +/- 0.3, 1.8 +/- 0.5, and 0.7 +/- 0.1 mm for the DBM+CS, DBM, CS, and GFS groups, respectively; the DBM+CS, DBM, and CS groups being different from the GFS group (P < 0.05), and the DBM+CS and DBM groups being different from the CS group (P < 0.05). None of the DBM-containing implants provided evidence of bone metabolic activity. In summary, surgical implantation of DBM and CS, alone or in combination, may result in significantly improved regeneration of alveolar bone and cementum in this preclinical model. Observed regeneration is likely unrelated to a biologic activity inherent in DBM. Rather it appears that space-providing properties of the implants supported observed regeneration.

Alveolar Bone Loss↗
PubMed1997

Immunoblot analyses on the differential distribution of NR2A and NR2B subunits in the adult rat brain.

Quantitative immunoblot analyses were carried out to study the distribution of N-methyl-D-aspartate (NMDA) receptor subunit 2A and 2B (NR2A and NR2B, respectively) at the protein level in the adult rat brain. Highest levels of NR2A were detected in cerebral cortex and hippocampus, followed at more or less similar levels (about 36-72% of cerebral cortex) by striatum, thalamus, olfactory bulb, superior and inferior colliculi, and cerebellum. The lowest levels were detected in midbrain and lower brain stem (30-31% of cerebral cortex). The NR2B was more dramatic in differential distribution than the NR2A. Highest levels of NR2B were found in telencephalic (olfactory bulb, cerebral cortex, hippocampus, and striatum) and thalamic regions, and expression in superior and inferior colliculi, midbrain, lower brain stem, and cerebellum were significantly lower (4-25% of cerebral cortex). Interestingly, NR2B proteins were barely detectable in the cerebellum. When the postsynaptic density (PSD) fractions were compared, the amount of NR2B in the cerebellar PSD fraction was only 1.8% of that present in the cerebral PSD fraction where the subunit is highly enriched. Immunoblot analyses with a phosphotyrosine-specific antibody showed that the molecular sizes of major phosphotyrosine-containing proteins in forebrain and hindbrain are 180 and 45 kDa, respectively. The regional distribution of the 180 kDa major phosphotyrosine protein was very similar to that of NR2B, and the protein could be immunoprecipitated by NR2B antibody. Our data shows that NR2A and NR2B subunits are differentially distributed in the brain in an overlapping manner, and that the major phosphotyrosine-containing protein of 180 kDa in forebrain is the NR2B.

Animals↗
PubMed1997

Developmental expression, subcellular localization, and tyrosine phosphorylation of NR2A and NR2B in the rat brain.

We carried out quantitative analyses of the developmental expression, subcellular localization of the N-methyl-D-aspartate receptor subunit 2A (NR2A) and 2B (NR2B), and tyrosine phosphorylation of NR2B. Immunoblot analyses showed that NR2A was not detected during the embryonic period and the first postnatal week but its expression reached 63.90% of adult at P14 and continued to increase until the fourth week, reaching a maximum at P30 (110% of adult). The NR2B was detected from as early as E14 (2.65% of adult) and its expression was transiently elevated at birth (43.73% of adult), decreasing for the first postnatal week, and then increased again rapidly in the second week (105.45% of adult at P14) with a maximum at P30 (123.34% of adult). There were 2.26 +/- 0.40-fold more NR2B than NR2A proteins in the forebrain PSD fractions, and NR2A and NR2B were enriched 2.75 +/- 0.35 and 4.65 +/- 0.25 fold, respectively, in the synaptosome, and 13.75 +/- 0.80 and 16.04 +/- 0.25-fold, respectively, in the PSD fraction from brain homogenate. The tyrosine phosphorylation of NR2B reached an adult level at around birth declining in the first postnatal week but recovered to the adult level by the end of the second week, while the amount of the protein itself increased 2.28-fold after birth, indicating that only a fraction of the proteins are phosphorylated in vivo. Our results indicate that expression and tyrosine phosphorylation of NR2B might be important for NMDA receptor functions in embryonic and early postnatal development.

Animals↗
PubMed1996

Characterization of densin-180, a new brain-specific synaptic protein of the O-sialoglycoprotein family.

We purified an abundant protein of apparent molecular mass 180 kDa from the postsynaptic density fraction of rat forebrain and obtained amino acid sequences of three tryptic peptides generated from the protein. The sequences were used to design a strategy for cloning the cDNA encoding the protein by polymerase chain reaction. The open reading frame of the cDNA encodes a novel protein of predicted molecular mass 167 kDa. We have named the protein densin-180. Antibodies raised against the predicted amino and carboxyl sequences of densin-180 recognize a 180 kDa band on immunoblots that is enriched in the postsynaptic density fraction. Immunocytochemical localization of densin-180 in dissociated hippocampal neuronal cultures shows that the protein is highly concentrated at synapses along dendrites. The message encoding densin-180 is brain specific and is more abundant in forebrain than in cerebellum. The sequence of densin-180 contains 17 leucine-rich repeats, a sialomucin domain, an apparent transmembrane domain, and a PDZ domain. This arrangement of domains is similar to that of several adhesion molecules, in particular GPIbalpha, which mediates binding of platelets to von Willebrand factor. We propose that densin-180 participates in specific adhesion between presynaptic and postsynaptic membranes at glutamatergic synapses.

Amino Acid Sequence↗
PubMed1996

Clinical implication of preoperative oral cholecystogram for laparoscopic cholecystectomy.

BACKGROUND: The aim of this study was to retrospectively assess the usefulness of the preoperative oral cholecystogram (OCG) as an index to the feasibility of laparoscopic cholecystectomy (LC) and the operative pathologic findings. Laparoscopic cholecystectomy has become the standard treatment for symptomatic gallbladder (GB) disease. However, no definite diagnostic modality that can predict the feasibility of LC and severity of pathologic anatomy has been proposed. METHODS: Retrospective data were collected on 240 consecutive patients undergoing LC at St. Vincent Hospital, Catholic University Medical College, from October 1991 until December 1993. Radiologic interpretations of OCG were standardized according to the method of Koehler and Kyaw--from grade 0 to 4. And the operative findings--pericholecystic adhesion, color of GB, and thickness of the GB wall--were evaluated simultaneously. RESULTS: The analysis showed that preoperative OCG can predict intraoperative GB perforation (p = 0.022), intraoperative controllable bleeding (p = 0.034), and operating time (p = 0.0001) according to the grade of visualization of GB. Grade 2- or -better visualized groups had more patients who had blue-colored GB (p = 0.000) and who had thin GB wall (p = 0.000). CONCLUSIONS: Preoperative oral cholecystogram may be an accurate index of the feasibility of laparoscopic cholecystectomy--represented by operating time and important intraoperative minor complications related to the operative pathological findings.

Adolescent↗
PubMed1996

Effects of polyglactin mesh combined with resorbable calcium carbonate or replamineform hydroxyapatite on periodontal repair in dogs.

This study evaluates periodontal repair and biomaterial reaction following implantation of a polyglactin mesh with or without porous resorbable calcium carbonate (RCC) or porous replamineform hydroxyapatite (RHA) in conjunction with reconstructive surgery. Ligature- and surgically-induced interproximal periodontal defects of left and right mandibular premolar teeth in 7 dogs were used. Bilaterally, mesial defects of the 2nd, 3rd and 4th premolar teeth were treated with polyglactin mesh, polyglactin mesh and RHA, or polyglactin mesh and RCC, respectively. The polyglactin mesh, shaped according to the contour of the defect, was adapted to the experimental teeth; its coronal margin positioned immediately apical to the cemento-enamel junction. Gingival flap margins were adapted and sutured to cover the polyglactin mesh completely. Clinical healing was generally uneventful. The dogs were sacrificed to provide block sections for histologic evaluation at 1, 3, 6, 12, 26, 32 and 56 weeks following wound closure. Generally, cementum regeneration was observed beginning at week 6 in all groups. Bone regeneration was observed from week 3 in polyglactin mesh-treated groups, and from week 6 in polyglactin mesh+RCC or polyglactin mesh+RHA treated groups. Bone regeneration appeared enhanced in polyglactin mesh+RCC or polyglactin mesh+RHA treated defects at week 12 and 26, with little difference between the three experimental conditions at week 56. Polyglactin mesh degradation was observed at week 3 and appeared complete at week 12. The RHA did not appear to resorb, while the RCC was gradually replaced by bone from week 3. Within limitations of the study conditions, periodontal regeneration was observed following implantation of a polyglactin mesh with or without RCC or RHA in conjunction with reconstructive surgery. As a conclusion, there seems to be no significant difference in periodontal regeneration after 12 months of healing between the group treated with the membrane only, and the group treated with the membrane and the bone substitution material. Changes in connective fiber orientation over the 1st 12 weeks of healing may suggest that "fibrous encapsulation" observed in earlier studies may only represent a transient stage in periodontal regeneration.

Animals↗
PubMed1996

Early graft dysfunction due to renal vein compression.

We here report on an unusual case of early renal transplant dysfunction due to renal vein compression. Graft function was initially good but oliguria and massive hematuria developed on the 3rd day after transplantation. Duplex sonography showed turbulent blood flow of the renal vein, and renal venography confirmed renal vein compression. Exploratory laparotomy was performed and diuresis was initiated just after nephropexy. In conclusion, renal vein compression is a rare complication but should be included in the possible causes of early renal transplant dysfunction since this can be simply diagnosed by duplex sonography and is easily remedied by nephropexy.

Adult↗
PubMed1994

The major tyrosine-phosphorylated protein in the postsynaptic density fraction is N-methyl-D-aspartate receptor subunit 2B.

The postsynaptic density (PSD) is a specialization of the submembranous cytoskeleton that is visible in the electron microscope on the cytoplasmic face of the postsynaptic membrane. A subcellular fraction enriched in structures with the morphology of PSDs contains signal-transduction molecules thought to regulate receptor localization and function in the central nervous system. We have purified a prominent tyrosine-phosphorylated glycoprotein of apparent molecular mass 180 kDa, termed PSD-gp180, that is highly enriched in the rat forebrain PSD fraction. The sequences of four tryptic peptides generated from the protein reveal that it is the 2B subunit of the N-methyl-D-aspartate (NMDA) type glutamate receptor. We have confirmed the identity of PSD-gp180 by showing that it reacts with antibodies raised against a unique fragment of the 2B subunit of the NMDA receptor. We also show that the 2B subunit is the most prominently tyrosine-phosphorylated protein in the PSD fraction based upon recognition by an anti-phosphotyrosine antibody. Two types of NMDA receptor subunits have been identified by molecular cloning [Nakanishi, S. (1992) Science 258, 597-603]. The single type 1 subunit is expressed throughout the brain and is necessary for formation of the receptor channel. The four type 2 subunits (2A, 2B, 2C, and 2D) are expressed in discrete brain regions, contain unusually long unique C termini, and confer distinct kinetic properties on NMDA receptors that contain them. Our findings suggest that, in the forebrain, NMDA receptor subunit 2B may serve to anchor NMDA receptors at the postsynaptic membrane through its interaction with the PSD. The prominent presence of tyrosine phosphate further suggests that the NMDA receptor may be regulated by tyrosine phosphorylation or that it may participate in signaling through tyrosine phosphorylation and through its ion channel.

Amino Acid Sequence↗
PubMedDate not supplied

Beneficial effects of prostglandin on rat cardiac allografts with cyclosporine immunosuppression.

Graft rejection is characterized by cellular infiltration, reduction in blood flow, and intravascular coagulation, finally resulting in graft failure and absolute increase in thromboxane and relative decrease in prostacyclin synthesis. It is also suspected that prostaglandin itself could cause prolongation of allograft survival. In this experimental study, after successful heterotopic cardiac transplantation in rats, CyA was administered by intramuscular injection and prostaglandin E1 (PGE1) given into the peritoneal cavity. Each dose was according to the experimental designs. The authors found that PGE1 in addition to CyA could provide beneficial effects with significantly increased cardiac allograft survival, with amelioration of pathological changes in allograft rejection reaction.

Animals↗