Electron microscopic evaluation of two-bundle anatomically reconstructed anterior cruciate ligament graft

We investigated the difference in collagen fibrils in the two-bundle anatomically reconstructed anterior cruciate ligament (ACL) and the one-bundle reconstructed ACL. Ten patients with a two-bundle anatomically reconstructed ACL using semitendinosus tendons (Two-ST) were followed for an average of 16 months (7-27 months) and were compared with 15 patients with a one-bundle ACL (One-ST) reconstruction using hamstring tendons followed for an average of 20 months (9-39 months). Biopsy was performed during second-look arthroscopy. The diameter of the collagen fibrils, their density, and the percentage of collagen fibrils were measured using electron micrography. We also investigated biopsy specimens of normal semitendinosus and gracilis tendons from 10 patients. The diameter of the collagen fibrils from hamstring tendons in the Two-ST (45.1 +/- 7.6 nm) was significantly larger than that in the One-ST (40.1 +/- 7.8 nm) ( P < 0.05). The diameter of the collagen fibrils in the normal hamstring tendons was significantly larger than that in the reconstructed ACL with hamstring tendons of the Two-ST and One-ST groups ( P < 0.01). The results of the study revealed that the diameter of collagen fibrils in the Two-ST was significantly greater than that in the One-ST. Hence, the tensile strength of the two-bundle graft may be greater than that of the one-bundle graft.

Major and minor capsid proteins of human polyomavirus JC cooperatively accumulate to nuclear domain 10 for assembly into virions

The human polyomavirus JC (JCV) replicates in the nuclei of infected cells. Here we report that JCV virions are efficiently assembled at nuclear domain 10 (ND10), which is also known as promyelocytic leukemia (PML) nuclear bodies. The major capsid protein VP1, the minor capsid proteins VP2 and VP3, and a regulatory protein called agnoprotein were coexpressed from a polycistronic expression vector in COS-7 cells. We found that VP1 accumulated to distinct subnuclear domains in the presence of VP2/VP3 and agnoprotein, while VP1 expressed alone was distributed both in the cytoplasm and in the nucleus. Mutation analysis revealed that discrete intranuclear accumulation of VP1 requires the presence of either VP2 or VP3. However, VP2 or VP3 expressed in the absence of VP1 showed diffuse, not discrete, nuclear localization. The C-terminal sequence of VP2/VP3 contains two basic regions, GPNKKKRRK (cluster 1) and KRRSRSSRS (cluster 2). The deletion of cluster 2 abolished the accumulation of VP1 to distinct subnuclear domains. Deletion of the C-terminal 34 residues of VP2/VP3, including both cluster 1 and cluster 2, caused VP1 to localize both in the cytoplasm and in the nucleus. Using immunoelectron microscopy of cells that coexpressed VP1, VP2/VP3, and agnoprotein, we detected the assembly of virus-like particles in discrete locations along the inner nuclear periphery. Both in oligodendrocytes of the human brain and in transfected cells, discrete nuclear domains for VP1 accumulation were identified as ND10, which contains the PML protein. These results indicate that major and minor capsid proteins cooperatively accumulate in ND10, where they are efficiently assembled into virions.

Histological and TEM Examination of Early Stages of Bone Healing after Er:YAG Laser Irradiation

OBJECTIVE

The aim of this study was to analyze the early healing process of bone tissue irradiated by Er:YAG laser and compare it with that treated by mechanical drilling and CO(2) laser.

BACKGROUND DATA

Er:YAG laser has a great potential for cutting hard tissues as it is capable of ablation with less thermal damage.

METHODS

Twenty-four male Wistar rats were used for this study. The calvarial bone of rats was exposed and straight grooves were prepared by Er:YAG laser, mechanical bur and continuous wave CO(2) laser. Four rats each were sacrificed at six time points: 10 min, 6 and 24 h and 3, 7, and 14 days post-surgery. Sections were prepared for light and transmission electron microscopic (TEM) observations.

RESULTS

Compared to mechanical bur and CO(2) groups, the inflammatory cell infiltration adjacent to the irradiated bone surface, fibroblastic reaction, and revascularization were more pronounced in the Er:YAG laser-irradiated tissues. A cell-rich granulation tissue with fibroblasts and osteoblasts was predominant in 7-day specimens of Er:YAG laser group. Histopathological analysis of 14-day specimens in the Er:YAG group also revealed significantly greater new bone formation, compared with the mechanical bur and CO(2) laser groups.

CONCLUSIONS

Initial bone healing following Er:YAG laser irradiation occurred faster than that after mechanical bur and CO(2) laser. Er:YAG laser treatment may be advantageous for wound healing of bone tissue, presumably by providing a favorable surface for cell attachment.

Suspended cells from trabecular bone by collagenase digestion become virtually identical to mesenchymal stem cells obtained from marrow aspirates

Several reports describe that the explant culture of the trabecular bone after collagenase treatment produces mesenchymal stem cells (MSCs). However, the suspended cells had not been intensively examined concerning MSCs. We hypothesized that the cells would acquire the properties of MSCs during their expansion and therefore compared them with marrow aspirate-derived MSCs. Human trabecular bones were washed, digested, filtered, and expanded clonally for 14 days. Their proliferation ability (n = 9) and differentiation potentials for chondrocyte, adipocyte, and osteoblast (n = 6) were similar with those of marrow aspirate-derived MSCs. Epitope and mRNA analysis revealed some differences in both types of cells, which disappeared with expansion and subcultivation. A mixed population of collagenase-released (CR) cells had similar differentiation potentials with CR clone, CD31(+) fraction, and osteoblastic cells. For quantitative study, trabecular bone and bone marrow were harvested by single aspiration using a biopsy needle (n = 16). Although the total nucleated cell number harvested was similar, the colony-forming efficiency of CR cells was approximately 100-fold higher than that of BM cells and more than 1 million CR cells could be obtained in 14 days from all donors. Enzymatically released cells from trabecular bone became virtually identical to marrow aspirate-derived MSCs, demonstrating that a trabecular bone fragment can be an alternative source of MSCs.

Amlodipine and carvedilol prevent cytotoxicity in cortical neurons isolated from stroke-prone spontaneously hypertensive rats

We previously reported that vitamin E prevents apoptosis in neurons during cerebral ischemia and reperfusion in stroke-prone spontaneously hypertensive rats (SHRSP). In this paper, we analyzed the effects of antihypertensives as well as vitamin E, which were added to neuron cultures after reoxygenation (20% O2) following hypoxia (1% O2). When added after hypoxia before reoxygenation, vitamin E conferred significant protection to neuronal cells. It was also shown that vitamin E conferred complete protection from neural cell death when added hypoxia and again before reoxygenation. At higher concentrations of vitamin E, strong neuroprotection was observed. Moreover, we verified that pretreatment with either amlodipine, carvedilol or dipyridamole consistently prevented cell death during hypoxia and reoxygenation (H/R). On the other hand, nilvadipine, a dihydropyridine-type calcium entry blocker, had no apparent effect on neuroprotection during H/R. The order of neuroprotective potency was vitamin E > dipyridamole > carvedilol > or = amlodipine > nilvadipine. In parallel experiments, we examined whether these antihypertensive agents were more effective when combined with vitamin E and dipyridamole. The results suggested that in our in vitro model system, antioxidants were the most important agents for the reduction of oxygen-free radical damage in cortical neurons. These findings suggest that amlodipine and carvedilol, with their antioxidant properties and antihypertensive activity, would be useful to inhibit neuronal cell death in the treatment of cerebrovascular stroke and neurodegenerative diseases in hypertensive patients.

Identification of hydroxyapatite deposits in the smooth muscle cells and ganglion cells of autopsied small intestines

We have studied the deposition of calcium salts in the autopsied intestines which have not been described previously as far as we were able to determine. In order to clarify the incidence, predisposing conditions, mineral compositions of the deposited materials and clinical significance of this phenomenon, we examined 76 cases of consecutive autopsied small intestines by von Kossa's staining. Deposited calcium salts were further examined by electron microscopically, energy-dispersive X-ray spectroscope and electron diffraction analysis. Deposition of calcium salts was observed in the small intestines of 13 cases. Among them, 10 cases were accompanied by hypercalcemia. Deposition of calcium salts was mainly observed in smooth muscle cells of the proper muscle layers and ganglion cells of the Auerbach's myenteric plexus. Intestinal calcinosis was frequently accompanied by deposition of calcium salts in the proper muscle layers of esophagus and large intestine, renal tubules and cardiac myocardial cells. Electron microscopically, the calcium salts were identified as needle-shaped crystals and located on the surface of the extracellular-collagen bundles, in the cytoplasm, mitochondria and nucleus of the smooth muscles cells. Energy-dispersive X-ray spectroscope and electron diffraction analysis suggested the deposited calcium salts as hydroxyapatite. Two patients among the six cases with moderate to severe calcium deposition showed clinical manifestation of paralytic ileus. In conclusion, intestinal calcinosis was frequently observed mostly associated with hypercalcemia. Calcium salts of hydroxyapatite were deposited to the smooth muscle cells and the Auerbach's myenteric plexus of the muscular layer. Deposition of calcium salts might occasionally causes the paralytic ileus but clinical significance of this lesion requires further examination.

Muscle-specific protein MDP77 specifically promotes motor nerve regeneration in rats

This study has examined the effects of recombinant human MDP77 (rhMDP77) on sciatic motor nerve regeneration in vivo. We carried out bridge grafting (14 mm) into the sciatic nerve of Sprague-Dawley rats using silicone tubes containing a mixture of type-I collagen and 0, 5, 10, or 20 microg/ml of rhMDP77, or containing phosphate-buffered solution (N = 6 in each group). Electrophysiological and histological evaluations carried out 12 weeks after implantation suggest that rhMDP77 has a positive effect on terminal and collateral sprouting of regenerating nerves and thereby promotes motor nerve regeneration in a dose-dependent manner.

Hydroxyapatite-coated tendon chitosan tubes with adsorbed laminin peptides facilitate nerve regeneration in vivo

On the inner surface of tendon chitosan tubes having a triangular shape and a hydroxyapatite coating (t-chitosan/HAp tube), laminin-1 and laminin peptides (YIGSR, IKVAV) have been adsorbed in order to develop nerve growth conduits. The mechanical property, biocompatibility and efficacy of these tubes for nerve regeneration were examined. Step-1: bridge grafting (15 mm) into the sciatic nerve of Sprague-Dawley (SD) rats was carried out using either t-chitosan or t-chitosan/HAp tubes having either a circular or triangular cross section (N=12 in each group). Specimens were taken after 2-, 4-, 6- and 8-week post-implantation (N=3 in each group) for histology determinations. Step-2: t-chitosan/HAp tubes having a triangular cross section with adsorbed laminin-1, CDPGYIGSR or CSRARKQAASIKVAVSAD, as well as control tubes without pre-adsorption were used for implantation (N=18 in each group). Isografting was also carried out (N=6). Histological evaluation was carried out similarly as in Step-1. Furthermore, evoked muscle and sensory nerve action potentials were recorded, and the percentage of myelinated axon area measured at 10 mm distance of the distal anastomosed site in the experimental, control and isograft groups after 12 weeks (N=6 in each group). The results of histological findings, as well as mechanical properties, suggest that a triangular tube shape with a HAp coating benefits nerve regeneration. The effect of laminin peptides (YIGSR, followed by IKVAV) to enhance the growth of regenerating axons has been found comparable with intact laminin-1. Although histological regeneration in both the YIGSR- and laminin-1-treated t-chitosan/HAp tubes matches the isografts, the functional recovery is however delayed.

Age-related changes in gap junctional protein of the rat heart

OBJECTIVE

Connexin 43 (Cx43), a membrane protein involved in the control of cell-to-cell communication, is thought to play a role in physiological processes such as tissue homeostasis, growth regulation and development. The aim of the present study was to investigate the change of Cx43 expression in aged myocardium.

METHODS AND RESULTS

Sixteen male Sprague-Dawley rats (adult: 10 weeks old, n=8; aged: two years old, n=8) were used in the present study. In an isolated rat heart Langendorff model, hearts were perfused for 10 min with a modified Krebs-Henseleit bicarbonate buffer. Contractile functions were measured and all hearts were stained with anti-Cx43 antibody for fluorescence microscopic examinations. There were no significant differences observed in heart rate (234+/-8.2 beats/min versus 231+/-15.6 beats/min), left ventricular developed pressure (112.5+/-6.3 mmHg versus 107.2+/-2.5 mmHg), first derivative of the left ventricular pressure (1450.4+/-165.1 mmHg/s versus 1384.6+/-95.4 mmHg/s) and coronary flow (17.4+/-0.7 mL/min versus 21.3+/-1.8 mL/min) between adult and aged rats, respectively. However, significant differences were observed in left ventricular weight (adult versus aged; 0.639+/-0.108 g versus 1.124+/-0.257 g, P=0.04) and in fluorescence examinations where there was reduced distribution of Cx43 in aged myocardium compared with adult myocardium.

CONCLUSIONS

These results demonstrated that the role of Cx43 may be more important than previously reported, and that this protein is partially responsible for the maintenance of cellular structure in myocardial development.

TEM observation of seven retrieved total knee joints made of Co-Cr-Mo and Ti-Al-V alloys

We demonstrate that a myriad of fine particles produced by the abrasion of both cobalt-chromium-molybdenum (Co-Cr-Mo) and titanium-aluminum-vanadium (Ti-Al-V) alloys accumulate in the synovial cells next to surgical implants made from these alloys. The metallic particles were of various sizes, and were observed within the lysosomes. Energy dispersive X-ray spectroscopy studies revealed that the fine spherical particles consisted solely of Cr, and that other larger particles were composed of the Co-Cr-Mo alloy. We measured the size of the metallic particles using the public domain NIH image program, and found that most of the fine spherical particles were 10-15 nm in diameter (n=1000). Eighty percent of the large particles were 30-35 nm in length and 20-25 nm in width (n=300). In addition, EDS examination clarified that all of the fine particles of the Ti-Al-V alloy were composed of that alloy. For this alloy, when discounting the larger particles, the fine metal deposits were 20-25 nm in length and 10-15 nm in width (n=1000). From these findings, we conclude that the Co-Cr-Mo alloy is easily corroded and that Co is released from the cells. In contrast, the Ti-Al-V alloy is very stable and does not corrode, although the Ti-Al-V alloy does produce particles that are smaller than those produced by the Co-Cr-Mo alloy.

Bone with a vascular flap induced from fat tissue with the use of rhBMP-2 in rats

Here we report that successful bone formation with a vascular flap inside a cylindrical mold was induced from fat tissue with the use of recombinant human bone morphogenetic protein-2 in rats. Fat tissue connected to blood vessels was prepared to fit into the mold and implanted intramuscularly into the hind leg in Wistar rats. RhBMP-2 (20 micro g) was applied in a collagen sheet previously placed on the inside surface of the mold. Bone formation was confirmed radiologically and morphologically at 2, 4, and 8 weeks after the surgery. In the control group without rhBMP-2 or the group with ligation of the blood vessels before the implantation, bone formation was not observed. Our success in bone formation having a definite size, shape, and blood supply may lead to a therapeutic approach to effective bone reconstitution. The present study is the first report on bone induction from fat tissue by rhBMP-2 in vivo.

Ultrastructural analysis of salivary calculus in combination with X-ray microanalysis

Ultrastructural studies of salivary calculi were performed. Scanning electron microscopic examination of the calculi revealed lamellar and concentric structures. Granular or globular structures and pyramid structures were found on the surface of the calculi, and in some cases a scaly structure corresponding to fiber and bacteria was recognized. X-ray microanalysis showed the main constitutes of the calculi to be Ca and P. Transmission electron microscopic examination revealed a fine fibrous structure near the degenerated organelles, and analyses of the structure by electron diffraction revealed hydroxyapatite. Calcification was found around the degenerative organelles in the form of lipid-like structures, mitochondria, lysosomes, and microbial structures. Judging from our results, as one of the processes leading to calculi formation, it is speculated that degenerative substances are emitted by saliva, by some phenomenon, and calcification around these substances then occurs, contributing to the formation of calculi.

Ultrastructural analysis of bone tissue irradiated by Er:YAG Laser

BACKGROUND AND OBJECTIVES

The use of erbium:yttrium aluminum garnet (Er:YAG) laser has been suggested for bone ablation, however, little is known about the nature of the tissue after irradiation. This study was aimed to analyze the ultrastructure of bone tissue treated with Er:YAG laser, as compared to those treated with CO(2) laser and bur drilling.

STUDY DESIGN/MATERIALS AND METHODS

Parietal bones of Wistar rats were treated and analyzed by light microscopy, transmission electron microscopy (TEM), electron diffraction analysis and energy dispersive X-ray spectroscopy (SEM-EDX).

RESULTS

This study demonstrated that Er:YAG laser irradiation resulted in a very thin changed layer of approximately 30 microm thickness, which consisted of two distinct sub-layers: a superficial, greatly altered layer and a deep, less affected layer.

CONCLUSIONS

The major changes found on bone surface after Er:YAG laser irradiation consisted of micro-cracking, disorganization, and slight recrystallization of the original apatites and reduction of surrounding organic matrix.

Genetic and ultrastructural demonstration of strong reversibility in human mesenchymal stem cell

We examined human bone marrow mesenchymal stem cells by applying real-time quantitative polymerase chain reaction (PCR) (RT-PCR) technology and electron-microscopic techniques. Our RT-PCR demonstrated that the values of peroxisome proliferation-activated receptor gamma2 (PPARgamma2) and lipoprotein lipase (LPL) mRNA dramatically increased according to adipogenic stimulation. The expressions of both PPARgamma2 and LPL mRNA were significantly reduced ( P<0.01) and almost disappeared after stimulation had ceased. The expressions of both genes, however, increased again by stimulation even though the cells were in a dedifferentiated state for a month. In the ultrastructural study, over 80% of the cells proceeded into morphologically well-developed adipocytes at the 12th day of induction/maintenance which were packed with lipid droplets and clusters. In the next process these lipid products were excreted from the cell bodies and the peripheral small parts containing numerous droplets were torn from the greater parts, which stuck tightly to each other and adhered to culture dishes. Adipocytes were not detected in the culture media during the final stage. The total cell number was equal to and over 90% of the cells dedifferentiated into fibroblast-like stem cells during the final maintenance period of 1 month. Furthermore the dedifferentiated cells quickly differentiated again into adipocytes by stimulation even if they were quiescent for 1 month. Thus we conclude that mesenchymal stem cells have strong reversibility from both the genetic and morphological points of view.

Choroidal vascular lesions identified by ICG angiography in a case of familial amyloidotic polyneuropathy

BACKGROUND

To describe a patient with familial amyloidotic polyneuropathy (FAP) whose choroidal vascular lesions were demonstrated dynamically with the use of indocyanine green (ICG) angiography.

CASE

A 59-year-old man complained of blurred vision due to vitreal amyloidosis in both eyes. Fundus examination after pars plana vitrectomy showed multiple retinal hemorrhages.

OBSERVATIONS

ICG angiography performed after vitrectomy clearly delineated multiple sites of hyperfluorescence indicating tissue staining alongside the major choroidal veins in the lower fundus of his left eye. ICG hyperfluorescence was more evident in the late angiographic phase. Fundus examination and fluorescein angiography revealed no abnormal findings at the corresponding sites of ICG dye leakage.

CONCLUSIONS

Choroidal vascular lesions in eyes with FAP were demonstrated in vivo using ICG angiography for the first time. ICG angiography may be very beneficial to evaluate occult choroidal involvement in patients with FAP.

The study of metal ion release and cytotoxicity in Co-Cr-Mo and Ti-Al-V alloy in total knee prosthesis - scanning electron microscopic observation

We surgically retrieved two cobalt(Co)-chromium(Cr)-molybdenum(Mo) and five titanium(Ti)-aluminum(Al)-vanadium(V) alloy knee prostheses from patients because of mechanical failure and pain. We examined the distribution of the small particles which were released from the Co-Cr-Mo and Ti-Al-V alloys using a backscattered scanning electron microscopy (SEM). In addition we analyzed the metals in the artificial knee joints and the tissues adjacent to them using energy dispersive X-ray spectroscopy (EDS). We demonstrated that a myriad of fine particles, produced by the abrasion of both Co-Cr-Mo and Ti-Al-V alloys, accumulated in the synovial cells. As Co-Cr-Mo alloys disintegrate easily in the cells, Co dissolves from the peripheral areas of them, although Cr remains within the cells. In contrast Ti-Al-V alloys are very stable in the synovial cells. From these findings we conclude that the Co-Cr-Mo alloys are hazardous to the body as the alloys release Co which enters the body. In contrast the Ti-Al-V alloys are very stable and are patently safer. Artificial joints, however, are still in considerable need of improvement.

Ultrastructure of oral sarcoma

Sarcoma of the oral region is extremely rare and ultrastructural studies of the tumor are limited in number. We collected oral sarcomas, such as fibrosarcoma, malignant fibrous histiocytoma, liposarcoma, leiomyosarcoma, rhabdomyosarcoma, angiosarcoma, alveolar soft-part sarcoma, solitary plasmacytoma, and osteosarcoma, and performed ultrastructural studies of these tumors. The value of these studies for an understanding of the biological behavior of the tumors was then investigated. In these studies, electron microscopic examinations of oral sarcoma were of assistance in our attempt to establish correct diagnosis and histogenesis. Data from the studies of oral sarcoma by light microscopy, electron microscopy, and immunohistochemistry should be accumulated.

Morphological analysis of cementum and root dentin after Er:YAG laser irradiation

BACKGROUND AND OBJECTIVES

To investigate the morphology of cementum and root dentin after Er:YAG laser irradiation with and without water coolant, compared to that after CO(2) laser irradiation and an untreated surface.

STUDY DESIGN/MATERIALS AND METHODS

Ten extracted healthy human teeth were used. Er:YAG and CO(2) lasers were applied with energy outputs of 0.4 W, with and without coolant and 0.5 W, without coolant, respectively. Scanning electron microscopy (SEM) analysis was performed at high and ultra-high magnifications.

RESULTS

The surface of cementum was micro-irregular with numerous projections while that of dentin appeared scaly after Er:YAG laser irradiation. Unlike after CO(2) laser treatment, no major melting or cracking was observed with Er:YAG laser treatment. The use of water spray produced fine micro-irregularities without attached debris. Ultra-high magnification revealed similar microparticles-composed aspects for both cementum and dentin. However, the more porous structure of the surface was observed after Er:YAG laser irradiation without water spray.

CONCLUSIONS

Cementum and root dentin presented distinct micro-roughness after Er:YAG laser irradiation, possibly due to structural differences in the original tissue. However, under ultra-high magnifications, both cementum and dentin presented similar characteristics of the irradiated surface. In addition, the use of water spray during laser irradiation minimized thermal effects and resulted in a cleaner and less porous surface.

Characterization of Ca(2+) signaling pathways in human mesenchymal stem cells

Human mesenchymal stem cells (HMSC) have the potential to differentiate into many cell types. The physiological properties of HMSCs including their Ca(2+) signaling pathways, however, are not well understood. We investigated Ca(2+) influx and release functions in HMSCs. In Ca(2+) imaging experiments, spontaneous Ca(2+) oscillations were observed in 36 of 50 HMSCs. The Ca(2+) oscillations were completely blocked by the application of 10 micro M cyclopiazonic acid (CPA) or 1 micro M thapsigargin (TG). A brief application of 1 micro M acetylcholine (ACh) induced a transient increase of [Ca(2+)](i) but the application of caffeine (10 mM) did not induce any Ca(2+) transient. When the stores were depleted with Ca(2+)-ATPase blockers (CPA or TG) or muscarinic agonists (ACh), store-operated Ca(2+) (SOC) entry was observed. Using the patch-clamp technique, store-operated Ca(2+) currents (I(SOC)) could be recorded in cells treated with ACh or CPA, but voltage-operated Ca(2+) currents (VOCCs) were not elicited in most of the cells (17/20), but in 15% of cells examined, small dihydropyridine (DHP)-sensitive Ca(2+) currents were recorded. Using RT-PCR, mRNAs were detected for inositol 1,4,5-trisphosphate receptor (InsP(3)R) type I, II, and III and DHP receptors alpha1A and alpha1H were detected, but mRNA was not detected for ryanodine receptor (RyR) or N-type Ca(2+) channels. These results suggest that in undifferentiated HMSCs, Ca(2+) release is mediated by InsP(3)Rs and Ca(2+) entry through plasma membrane is mainly mediated by the SOCs channels with a little contribution of VOCCs.

Oral squamous cell carcinoma: electron microscopic and immunohistochemical characteristics

Oral squamous cell carcinoma is the most common oral malignancy, and we performed electron microscopic and immunohistochemical investigation of the tumor. In patients with cervical metastasis, microvilli were developed and a small number of desmosomes were found, regardless of the width of the intercellular spaces. In patients without the metastasis, few microvilli were found in relatively wide intercellular spaces, or numerous microvilli were found in narrow intercellular spaces, and a large number of desmosomes were shown. However, these findings were different from those of tumors that had received radiotherapy, in which numerous microvilli and a small number of desmosomes were found in the nonmetastatic cases. Transferrin receptor, which is a marker of cell proliferation, was localized on the cell membrane, especially in microvilli. Ultrastructural similarity between the primary tumor and the metastatic tumor was recognized, however, the features of microvilli, desmosomes, and the intercellular spaces differed between them in most cases. It is suggested that microvilli might be related to the metastasis of oral squamous cell carcinoma cells. Immunohistochemically, the protein expression of p53 and pRb2/p130 was related to the clinical course of the patients with oral squamous cell carcinoma; the mechanism of the synthesis of these proteins should be investigated in order to understand the biological behavior of the tumor.

An ultrastructural study of calcifying odontogenic cyst, especially calcified material

The ultrastructural features of calcification in a case of calcifying odontogenic cyst (COC) were studied. Scanning electron microscopic examination of the inner parts of the cyst wall revealed many short microvilli, and X-ray microanalysis of the high-density masses in the intercellular parts showed prominent calcium peaks, which meant that these masses were calcified materials. On transmission electron microscopic observations, many calcifications exhibited a distinctive ring formation around the periphery of a central core that consisted of an amorphous structure. These calcifications were observed with necrotic remnants of nuclear material and many identifiable mitochondria, thin fibers, and epithelial cells. The cytoplasm of ghost cells consisted of numerous short electron-dense tonofilament bundles. Needle-like structures were shown in the tonofilament bundles. X-ray diffraction analysis showed that the needle-like crystals were hydroxyapatite. It is suggested that calcification in a COC may be related to degenerative mitochondria and tonofilament bundles of ghost cells.

Scanning electron microscopy and Fourier transformed infrared spectroscopy analysis of bone removal using Er:YAG and CO2 lasers

BACKGROUND

A thorough analysis of laser-ablated bone tissue is required before applying the technique to osseous surgery. In this study, we examine the morphological features and chemical composition of the bone surface after Er:YAG and CO2 lasers ablation.

METHODS

Six Wistar rats were used. An Er:YAG laser was used for ablation at an output energy of 100 mJ/pulse and a pulse rate of 10 Hz (1 W). Continuous CO2 laser irradiation was performed at an output energy of 1 W. Sites drilled using a conventional micromotor were used as controls. Analysis using scanning electron microscopy (SEM) and Fourier transformed infrared (FTIR) spectroscopy was performed.

RESULTS

Er:YAG laser ablation produced a groove with similar dimensions to that produced by bur drilling, whereas the CO2 laser produced only a charred line with minimal tissue removal. SEM observations revealed that the groove produced by the Er:YAG laser had well-defined edges and a smear layer-free surface with a characteristically rough appearance and with entrapped fibrin-like tissue. The melting and carbonization produced by the CO2 laser were not observed on sites irradiated by the Er:YAG laser. FTIR spectroscopy revealed that the chemical composition of the bone surface after Er:YAG laser ablation was much the same as that following bur drilling. The production of toxic substances that occurred after CO2 laser irradiation was not observed following Er:YAG laser irradiation or bur drilling.

CONCLUSION

These results suggest that the use of Er:YAG laser ablation may become an alternative method for oral and periodontal osseous surgery.

Microvilli and desmosomes of squamous cell carcinoma cells in tongue carcinoma related to regional lymph node metastasis: ultrastructural and immunohistochemical studies with transferrin receptor

Squamous cell carcinomas of the tongue (n = 49), consisting of 21 cases with cervical lymph node metastasis and 28 nonmetastatic cases, were examined by electron microscopy with special emphasis on tumor cell attachment. No difference of tumor size (T classification) or pathological findings between the metastatic group and the nonmetastatic group was found. The metastatic cases had numerous microvilli and a small number of desmosomes regardless of the width of the intercellular spaces. The nonmetastatic cases had few microvilli in relatively wide intercellular spaces, or, in the cases in which numerous microvilli were present in the narrow intercellular spaces, the tumor cells were connected by a large number of desmosomes. Transferrin receptor, which is a marker of cell proliferation, was localized in the cell membrane by immunohistochemistry and especially in microvilli by immunoelectron microscopy. It is suggested that microvilli might be related to the proliferation and the metastasis of squamous cell carcinoma cells.

Investigation of titanium leak to bone tissue surrounding dental titanium implant: electron microscopic findings and analysis by electron diffraction

This study investigated the tissue response associated with dental titanium implants. The mandibular third and fourth premolars and first molar of three adult beagle dogs were extracted bilaterally. Healing was then allowed for 3 months. Six titanium implants were placed in the mandibles of a dog. Three weeks after the implantation, mandibular sections containing the implants were retrieved with the use of a bone saw and investigated by light and electron microscopy, X-ray microanalyzer, and electron diffraction. Scanning electron microscopic observation showed titanium particles on the implant-bone interface, and investigation by microanalyzer revealed titanium not only on the implant-bone interface but also in the bone tissue. Transmission electron microscopic observation and investigation by electron diffraction showed titanium in the bone matrix and cells other than macrophages. In this study, titanium particles from the dental implant were recognized morphologically in the surrounding bone tissue. Thus, study of the influence of titanium particles on the human body is needed.

Calcific deposits on degraded shunt catheters: long-term follow-up of V-P shunts and late complications in three cases

OBJECT

Three cases with late complications and nine cases without late complications are presented to demonstrate the long-term results of ventriculoperitoneal (V-P) shunting, particularly those concerning degradation and mineral deposits of shunt catheters.

METHODS

Plain X-rays were taken in every case to detect any calcification. The catheters removed following late complications were examined in a scanning electron microscope (SEM). Spectroscopy and conventional histology were also performed.

CONCLUSION

Routine histology, spectroscopy, and SEM revealed that the mineral deposits consisted of hydroxyapatite. Plain X-ray and operative findings showed that the most extensive calcification was present in the neck, where the catheters were subject to heavy mechanical stress. No calcification was detected on catheters that did not contain barium particles. Our findings indicate that mechanical stress contributes to the process of degradation, and that barium sulfate admixed with silicone during the manufacturing process might accelerate late complications owing to the formation of cracks in the catheters and by enhancing the nucleation rate.