Morphological and functional changes in regenerated primary afferent fibres following mental and inferior alveolar nerve transection

BACKGROUND

It is important to know the mechanisms underlying pain abnormalities associated with inferior alveolar nerve (IAN) regeneration in order to develop the appropriate treatment for orofacial neuropathic pain patients. However, peripheral mechanisms underlying orofacial pain abnormalities following IAN regeneration are not fully understood.

METHODS

Head withdrawal threshold (HWT), jaw opening reflex (JOR) thresholds, single-fibre recordings of the regenerated mental nerve (MN) fibres, calcitonin gene-related peptide (CGRP), isolectin B4 (IB4), peripherin, neurofilament-200 (NF-200) and transient receptor potential vanilloid 1 (TRPV1) expression in trigeminal ganglion (TG) cells, and electron microscopic (EM) observations of the regenerated MN fibres were studied in MN- and IAN-transected (M-IANX) rats.

RESULTS

HWT to mechanical or heat stimulation of the mental skin was significantly lower in M-IANX rats compared with sham rats. Mean conduction velocity of action potentials recorded from MN fibres (n = 124) was significantly slower in M-IANX rats compared with sham rats. The percentage of Fluoro-Gold (FG)-labelled CGRP-, peripherin- or TRPV1-immunoreactive (IR) cells was significantly larger in M-IANX rats compared with that of sham rats, whereas that of FG-labelled IB4- and NF-200-IR cells was significantly smaller in M-IANX rats compared with sham rats. Large-sized myelinated nerve fibres were rarely observed in M-IANX rats, whereas large-sized unmyelinated nerve fibres were frequently observed and were aggregated in the bundles at the distal portion of regenerated axons.

CONCLUSIONS

These findings suggest that the demyelination of MN fibres following regeneration may be involved in peripheral sensitization, resulting in the orofacial neuropathic pain associated with trigeminal nerve injury.

Octacalcium phosphate collagen composites with titanium mesh facilitate alveolar augmentation in canine mandibular bone defects

This study was designed to investigate whether bone regeneration by implantation of octacalcium phosphate and porcine atelocollagen composite (OCP/Col) would be enhanced if mechanical stress to the implanted OCP/Col were alleviated. OCP/Col discs were implanted into an arc-shaped mandibular defect in male adult beagle dogs divided into untreated, OCP/Col, and OCP/Col/Mesh groups. In the OCP/Col/Mesh group, mechanical stress towards the implanted OCP/Col was alleviated by a titanium mesh. Bone regeneration in the three groups was compared after 6 months. Macroscopically, the alveolus in the OCP/Col/Mesh group was augmented vertically more than in the other two groups. Morphometric analysis by micro-CT showed the bone volume in the OCP/Col/Mesh group was significantly greater than in the other two groups. The augmented alveolus in the OCP/Col/Mesh group consisted of outer cortical and inner cancellous structure. Histologically, the OCP/Col/Mesh-treated alveolus was augmented by matured bone tissue along the inside of the titanium mesh. The implanted OCP/Col in the OCP/Col/Mesh and OCP/Col groups had almost disappeared. These results indicated that vertical bone regeneration by OCP/Col was efficient and successful when the mechanical stress to the implanted OCP/Col was alleviated. OCP/Col should be a useful bone substitute with active structural reconstitution.

Bone regeneration by octacalcium phosphate collagen composites in a dog alveolar cleft model

Octacalcium phosphate (OCP) and porcine atelocollagen sponge composites (OCP/Col) markedly enhanced bone regeneration in a rat cranial defect model. To assess clinical application, the authors examined whether OCP/Col would enhance bone regeneration in an alveolar cleft model in an adult dog, which was assumed to reflect patients with alveolar cleft. Disks of OCP/Col or collagen were implanted into the defect and bone regeneration by OCP/Col or collagen was investigated 4 months after implantation. Macroscopically, the OCP/Col-treated alveolus was obviously augmented and occupied by radio-opacity, and the border between the original bone and the defect was indistinguishable. Histological analysis revealed it was filled and bridged with newly formed bone; a small quantity of the remaining implanted OCP was observed. X-ray diffraction patterns of the area of implanted OCP/Col indicated no difference from those of dog bone. In the collagen-treated alveolus, the hollowed alveolus was mainly filled with fibrous connective tissue, and a small amount of new bone was observed at the defect margin. These results suggest that bone was obviously repaired when OCP/Col was implanted into the alveolar cleft model in a dog, and OCP/Col would be a significant bone regenerative material to substitute for autogeneous bone.

Appositional Bone Formation by OCP-Collagen Composite

Synthetic octacalcium phosphate (OCP) has been shown to enhance bone formation and to biodegrade if implanted into bone defects. Here, we hypothesized that an OCP-atelocollagen complex (OCP/Col) is biodegradable and can induce bone formation in a thickness-dependent manner when implanted into the calvaria. OCP/Col disks (diameter, 9 mm; thickness, 1 or 3 mm) were implanted into a subperiosteal pocket in the calvaria of 12-week-old Wistar rats for 4, 8, and 12 weeks and subsequent bone formation was monitored. X-ray diffraction analysis and Fourier transform infrared spectroscopy showed that OCP in the OCP/Col implants was converted into a carbonate-rich apatite after 4 weeks. Although thinner disks tended to be replaced by new bone, thicker disks were progressively resorbed by osteoclast-like cells until 12 weeks, possibly via the increased mechanical load in the subperiosteal pocket. Therefore, OCP/Col can increase appositional intra-membranous bone formation if the appropriate size of the implant is applied.

Analysis of appositional bone formation using a novel rat experimental model

AIM

To analyze the process of appositional bone formation using our original rat experimental model.

MATERIALS AND METHODS

Rats were anesthetized and a ring made of polytetrafluorethylene was placed on the parietal bone surface in the surgical procedure. The time course of appositional bone formation was analyzed with histomorphometry and in situ hybridization for type I collagen and bone sialoprotein.

RESULTS

The rat experimental model allowed new bone to be formed on the pre-existing bone surface and persist for 12 weeks. We demonstrated that bone is apposed actively for the first 4 weeks and less actively thereafter.

CONCLUSIONS

The experimental model may contribute to biological analysis for appositional bone formation expected to occur in clinical procedures such as alveolar bone augmentation and sinus lifting.

Bone regeneration by synthetic octacalcium phosphate and its role in biological mineralization

Octacalcium phosphate (Ca8H2(PO4)6 * 5H2O; OCP) has been advocated to be a precursor of biological apatite crystals in bone and tooth. Recent studies, using physical techniques, showed that OCP is present as a transient phase during biological apatite formation in human dentin, porcine enamel and murine bone. However, there is still a controversy regarding the chemical nature of the first mineral formed in the biominerals. A number of studies have demonstrated that synthetic OCP shows bone regenerative and biodegradable characteristics, rather than other calcium phosphate bone substitute materials, such as hydroxyapatite (Ca10(PO4)6(OH)2; HA) ceramic. It seems likely that synthetic OCP may be an alternative to autogenous bone graft. It is known that OCP contains alternative layers of water molecules and an apatite structure, and that the transition of OCP to HA is likely to be spontaneous and irreversible. The conversion process induces modification of local environment adjacent to OCP surface, including the changes in adsorption of serum proteins and concentration of calcium and inorganic phosphate ions. This article reviews the possible application to bone regeneration by synthetic OCP and the mechanism to enhance bone regeneration in relation to biological mineralization in bone and tooth.

Formation of bone-like apatite enhanced by hydrolysis of octacalcium phosphate crystals deposited in collagen matrix

It has been shown that granules of synthetic octacalcium phosphate (OCP) or the composites with collagen are capable of enhancing bone regeneration, accompanied by a gradual conversion from OCP to apatite with time. The present study was designed to investigate whether formation of bone-like apatite can be accelerated by OCP deposited throughout collagen matrix (OCP collagen complex, OCC) immersed in simulated body fluid (SBF). The formation of bone-like apatite has been suggested to be essential to induce osteoconductivity of various substrates. The formation of OCP in collagen solution was investigated in calcium or phosphate ions in the range between 22.5 and 142.5 mM and pH 6.26 and 8.56. X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy (SEM) showed that condition to nucleate OCP was limited to that of a solution with Ca/P 0.43 around pH 7.16 in the presence of collagen. OCP was shown to be formed throughout the collagen matrix by SEM observation. The immersion of OCC in SBF up to 10 days enhanced apatite crystal deposition, probably through OCP-apatite conversion: the apatite formation in OCC took place within only 1 day. The present study indicated that the existence of OCP deposited throughout the collagen matrix promotes bone-like apatite formation under physiological condition.

Genetic variations and haplotype structures of the ABCB1 gene in a Japanese population: an expanded haplotype block covering the distal promoter region, and associated ethnic differences

As functional ABCB1 haplotypes were recently reported in the promoter region of the gene, we resequenced the ABCB1 distal promoter region, along with other regions (the enhancer and proximal promoter regions, and all 28 exons), in a total of 533 Japanese subjects. Linkage disequilibrium (LD) analysis based on 92 genetic variations revealed 4 LD blocks with the same make up as previously described (Blocks -1, 1, 2 and 3), except that Block 1 was expanded to include the distal promoter region, and that a new linkage between polymorphisms -1,789G>A in the distal promoter region and IVS5 + 123A>G in intron 5 was identified. We re-assigned Block 1 haplotypes, and added novel haplotypes to the other 3 blocks. The reported promoter haplotypes were further classified into several types according to tagging variations within Block 1 coding or intronic regions. Our current data reconfirm the haplotype profiles of the other three blocks, add more detailed information on functionally-important haplotypes in Block 1 and 2 in the Japanese population, and identified differences in haplotype profiles between ethnic groups. Our updated analysis of ABCB1 haplotype blocks will assist pharmacogenetic and disease-association studies carried out using Asian subjects.

Serum amiodarone and desethylamiodarone concentrations following nasogastric versus oral administration

OBJECTIVE

Hospitalized patients unable to ingest anything by mouth require nutritional support by enteral feeding and administration of drugs through a nasogastric tube inserted into the digestive tract. Nasogastric administration of amiodarone may not always be equivalent to oral administration of amiodarone.

METHODS

We collected 162 observations of serum amiodarone and desethylamiodarone metabolite concentrations from 93 patients within 60 days of starting treatment with amiodarone. Eight patients were given the drug nasogastrically and 85 patients, orally. The two groups, were compared in terms of their serum concentration/(dose/weight) (C/D) value. A ratio of serum amiodarone concentration to serum desethylamiodarone concentration (AMD/DEA) was calculated for each sample. In addition, the percentage drug recovery after nasogastric administration of amiodarone was analysed.

RESULTS

Significant differences were observed in C/D values of amiodarone and desethylamiodarone and in AMD/DEA values of patients given amiodarone orally when compared with those given the drug nasogastrically. The C/D values of patients who received their medication nasogastrically were approximately 30% of the C/D values of patients who received their medication orally. Approximately 70% of the drug was recovered after it had passed through the nasogastric tube.

CONCLUSIONS

To achieve similar concentrations, an approximately 3-fold increase in dosage of amiodarone was required when patients were given the drug nasogastrically rather than orally. This suggests that the absorption of amiodarone following nasogastric administration is poor when compared with oral administration. Therapeutic drug monitoring is necessary to optimize dose particularly during the early stages of amiodarone therapy.

Genetic polymorphisms and haplotypes of the human cardiac sodium channel alpha subunit gene (SCN5A) in Japanese and their association with arrhythmia

Genetic variations in cardiac ion channels have been implicated not only as the causes of inherited arrhythmic syndromes, but also as genetic risk factors for some acquired arrhythmias. To elucidate the potential roles of genetic polymorphisms of the alpha subunit of the voltage-gated sodium channel type V (SCN5A) in cardiac rhythm disturbance, the entire SCN5A coding exons and their flanking introns were sequenced in 166 Japanese arrhythmic patients and 232 healthy controls. We detected 69 genetic variations, including 54 novel ones. Out of the 12 novel nonsynonymous single nucleotide polymorphisms (SNPs), p.Leu1988Arg was found at a frequency of 0.015. The other 11 SNPs were rare (0.001), with 6 found in arrhythmic patients and 5 in healthy controls. The frequency of a novel intronic SNP, c.703+130G>A, was significantly higher in the patients than in the controls, suggesting this SNP is associated with an unknown risk factor for arrhythmia. Following linkage disequilibrium analysis, the haplotype structure of SCN5A was inferred using high-frequency SNPs. The frequency of the haplotype harbouring both p.Leu1988Arg and the common SNP p.His558Arg (haplotype GG) was significantly lower in the patients than in the controls. This finding suggests that this haplotype (GG) might have been positively selected in the controls because of its protective effect against arrhythmias. This study provides fundamental information necessary to elucidate the effect of genetic variations in SCN5A on channel function and cardiac rhythm in Japanese, and probably in the Asian population.

Haplotype structures of the UGT1A gene complex in a Japanese population

Genetic polymorphisms of UDP-glucuronosyltransferases (UGTs) are involved in individual and ethnic differences in drug metabolism. To reveal co-occurrence of the UGT1A polymorphisms, we first analyzed haplotype structures of the entire UGT1A gene complex using the polymorphisms from 196 Japanese subjects. Based on strong linkage disequilibrium between UGT1A8 and 1A10, among 1A9, 1A7, and 1A6, and between 1A3 and 1A1, the complex was divided into five blocks, Block 8/10, Block 9/6, Block 4, Block 3/1, and Block C, and the haplotypes for each block were subsequently determined/inferred. Second, using pyrosequencing or direct sequencing, additional 105 subjects were genotyped for 41 functionally tagged polymorphisms. The data from 301 subjects confirmed the robustness of block partitioning, but several linkages among the haplotypes with functional changes were found across the blocks. Thus, important haplotypes and their linkages were identified among the UGT1A gene blocks (and segments), which should be considered in pharmacogenetic studies.

Identifying patterns of spatial current dispersion that characterise and separate the Brugada syndrome and complete right-bundle branch block

The aim of the study was to detect patterns of spatial-current distribution in the late QRS and early ST-segments that distinguish Brugada-syndrome cases from complete right-bundle branch block (CRBBB). Magnetocardiograms (MCGs) were recorded from Brugada-syndrome patients (n = 6), CRBBB patients (n = 4) and the members of a control group (n = 33). The current distributions at six time points from Q-onset were estimated by producing current-arrow maps (CAMs). The angle of the current arrow of maximum amplitude at each time point was calculated. In the Brugada cases, the characteristic ST elevation was seen above the upper right chest, and abnormal currents appeared to be present in the right-ventricular outflow tract (RVOT). The angles of the abnormal arrows were -78 degrees +/- 51 degrees at 100 ms and -50 degrees +/- 61 degrees at 110 ms. In the cases of CRBBB, wide S- and R-waves were recorded above the upper right and lower right chest, respectively. The angles of the abnormal arrows for CRBBB were 152 degrees +/- 19 degrees at 100 ms, 159 degrees +/- 20 degrees at 110 ms, and 157 degrees +/- 19 degrees at 120 ms. The findings suggest that an abnormal current from the RVOT to the upper left chest may be a feature of the Brugada syndrome, and that the direction of this current is completely different from that seen in CRBBB.

New scaffold for recombinant human bone morphogenetic protein-2

A bioactive and resorbable scaffold is necessary to exhibit the osteoinductive potency of recombinant human bone morphogenetic protein-2 (rhBMP-2). In a previous study, we found that synthetic octacalcium phosphate (OCP) enhances bone regeneration and is replaced by newly formed bone after it is resorbed. We hypothesized that OCP may be useful as an effective scaffold for rhBMP-2 to enhance bone regeneration. To test this hypothesis, the present study was designed to investigate whether an OCP/BMP composite implant could more effectively enhance bone regeneration. A critical-sized defect was made in a rat calvarium and 1. 15 mg of OCP combined with 10 microg of rhBMP-2 (OCP/BMP 10 microg), 2. 15 mg of OCP combined with 1 microg of rhBMP-2 (OCP/BMP 1 microg), or 3. OCP (OCP alone) was implanted into the defect and fixed at 4 or 8 weeks after implantation. The percentage of newly formed bone (n-Bone%) in the defect was determined by a histomorphometrical analysis. A statistical analysis showed that n-Bone% with OCP/BMP was significantly higher than that with OCP at both time points, whereas the difference in n-Bone% between OCP/BMP 10 microg and OCP/BMP 1 microg was not significant. The present results suggest that OCP can be used as an effective scaffold for rhBMP-2 and this OCP delivery system may be able to reduce the standard effective dose of rhBMP-2, which would be beneficial because low doses (<100 microg/g OCP) of rhBMP-2 enhance bone regeneration.

Preliminary report of two-stage secondary alveolar bone grafting for patients with bilateral cleft lip and palate

OBJECTIVE

To overcome the difficulties of one-stage secondary alveolar bone grafting for patients with bilateral cleft lip and palate (BCLP) who have a broad alveolar cleft, the value of two-stage alveolar bone grafting was examined.

PATIENTS

Three patients (2 girls and 1 boy) with BCLP were treated by two-stage alveolar bone grafting. The procedure consisted of a first-stage surgery (mean age 8 year 6 months +/- 7.8 months), which consisted of alveolar bone grafting for one side of the BCLP, and second-stage surgery for the contralateral side several months later. For the postoperative assessment, radiographs of the operated site were examined.

RESULTS

The average amount of implanted bone per operation and per patient was 6.8 +/- 1.1 g and 13.7 +/- 1.0 g, respectively. Postoperative clinical and radiographic examinations revealed that an appreciable alveolar bone ridge had formed, and there were no major complications.

CONCLUSIONS

Two-stage alveolar bone grafting, which makes it possible to reduce the amount of implanted bone, could be an optional surgical procedure for patients with BCLP and a broad alveolar cleft.

Differential expression of cornified cell envelope precursors in normal skin, intraorally transplanted skin and normal oral mucosa

BACKGROUND

Skin flaps have routinely been used as substitutes for oral mucosa after extensive resection of oral tissues. However, it remains unknown how the transplanted skin flaps perform as a host defence in the new environment of the oral cavity.

OBJECTIVES

To evaluate the expression of cornified cell envelope (CCE) precursors in pretransplanted (normal) skin, intraorally transplanted skin and normal oral mucosa, because CCEs are highly responsible for a protective barrier in each type of epithelium.

METHODS

We used immunohistochemistry and immunoelectron microscopy to examine the expression of CCE precursors, small proline-rich protein (SPR) 2 and 3 and loricrin, in biopsy specimens of normal skin, transplanted skin and normal oral mucosa, including buccal and lingual (non-keratinized) mucosae, and palatal (keratinized) mucosa.

RESULTS

Transplanted skin flaps were classified into two groups. About two-thirds of the transplanted skin flaps displayed a reddish appearance and were devoid of the stratum corneum (SC) together with a psoriasiform inflammatory tissue reaction. Others showed a native appearance, retaining the SC. While SPR2 expression was limited to the stratum granulosum (SG) in both normal and transplanted skin retaining the SC, it extended to the stratum spinosum (SS) of the transplanted skin lacking the SC and that of the normal oral mucosa. Although SPR3 expression was not found in normal skin or in the transplanted skin retaining the SC, it was strongly expressed in the SS of the transplanted skin lacking the SC and the non-keratinized oral mucosa, and in the SS and SG of the keratinized oral mucosa. Loricrin, which was expressed in the SG of normal skin, the transplanted skin retaining the SC and the keratinized oral mucosa, was not detected in the transplanted skin lacking the SC or in the non-keratinized oral mucosa. Immunoelectron microscopy confirmed the ultrastructural localization of SPR3 directly under the cytoplasmic membrane of keratinocytes of the transplanted skin lacking the SC and that of the oral mucosa.

CONCLUSIONS

The altered expression of SPR2, SPR3 and loricrin reflects the possible adaptation of epidermal keratinocytes in the new environment of the oral cavity.

Abnormal response to sodium channel blockers in patients with Brugada syndrome: augmented localised wall motion abnormalities in the right ventricular outflow tract region detected by electron beam computed tomography

OBJECTIVE

To investigate the relation between the wall motion abnormalities and sodium channel abnormalities in cases of the Brugada syndrome.

DESIGN

Consecutive prospective case-control study in a single hospital.

SETTING

Tertiary referral centre.

PATIENTS

13 consecutive patients with Brugada syndrome and 13 age and sex matched control subjects.

INTERVENTIONS

Each subject underwent electron beam computed tomography (EBT) and a 12 lead ECG before and after disopyramide injection.

MAIN OUTCOME MEASURES

QRS width and the magnitude of ST segment elevation in the 12 lead ECG; wall motion by EBT.

RESULTS

After disopyramide, EBT revealed deterioration of focal wall motion abnormalities in the right ventricular outflow tract region in eight of the 13 patients (62%). Prolongation of the QRS width after disopyramide injection in lead V2, which usually reflects the electrical activity in right ventricular outflow tract region, was greater in these eight patients (p < 0.01) than in the other five patients, in whom wall motion did not change after disopyramide. The degree of augmentation of ST segment elevation did not differ significantly between the two groups

CONCLUSIONS

The deterioration of wall motion abnormalities in the right ventricular outflow tract region after disopyramide suggests the presence of functional abnormalities of the sodium channel. Some patients with Brugada syndrome may have arrhythmogenic substrates with abnormal responses to sodium channel blockers.

Gene-specific response of dynamic ventricular repolarization to sympathetic stimulation in LQT1, LQT2 and LQT3 forms of congenital long QT syndrome

AIMS

Differences in the sensitivity of the genotype of the congenital long QT syndrome to sympathetic stimulation have been suggested. This study compared the influence of sympathetic stimulation on continuous corrected QT (QTc) intervals between LQT1, LQT2 and LQT3 forms of the congenital long QT syndrome.

METHODS AND RESULTS

We recorded a 12-lead electrocardiogram continuously before and after bolus injection (0.1 microg x kg(-1)) of epinephrine followed by continuous infusion (0.1 microg x kg(-1) min(-1)) in 12 LQT1, 10 LQT2, 6 LQT3, and 13 control patients. The QT intervals and previous RR intervals of all beats were measured semi-automatically, and the QTc intervals of all beats were calculated by Bazett's method. The dynamic response of the RR interval to epinephrine was no different between the four groups. The QTc was prolonged remarkably (477+/-42 to 631+/- 59 ms; P<0.0005, % delta prolongation =+32%) as the RR was maximally decreased (at peak of epinephrine), and remained prolonged at steady state conditions of epinephrine (556+/-56 ms; P<0.0005 vs baseline, +17%) in LQT1 patients. Epinephrine also prolonged the QTc dramatically (502+/-23 to 620+/-39 ms; P<0.0005, +24%) at peak of epinephrine in LQT2 patients, but this shortened to baseline levels at steady state (531+/-25 ms; P=ns vs baseline, +6%). The QTc was much less prolonged at peak of epinephrine in LQT3 (478+/-44 to 532+/-41 ms; P<0.05, +11%) and controls (394+/-21 to 456+/-18 ms; P<0.0005, +16%) than in LQT1 and LQT2 patients, and shortened to the baseline levels (LQT3; 466+/-49 ms, -3%, controls; 397+/-16 ms, +1%; P=ns vs baseline) at steady state.

CONCLUSION

Our data suggest that the dynamic response of ventricular repolarization to sympathetic stimulation differs between LQT1, LQT2 and LQT3 syndromes, and may explain why the trigger of cardiac events differs between the genotypes.

Catecholamines in children with congenital long QT syndrome and Brugada syndrome

Catecholamines have long been used as a provocative test in some forms of tachyarrhythmias including long QT syndrome (LQTS). In contrast, catecholamines are reported to decrease ST-segment elevation in leads V1-V3 in some patients with Brugada syndrome. Differential effects of catecholamines on QT interval, action potential duration, transmural dispersion of repolarization and Torsade de Pointes between LQT1, LQT2, and LQT3 forms of the LQTS were shown in experimental models of the LQTS by using arterially-perfused wedge preparations as well as in patients with congenital LQTS including children. In our preliminary result of patients with Brugada syndrome including a child, isoproterenol infusion was effective to decrease the ST-segment elevation in leads V1-V2 and to suppress the electrical storm of ventricular fibrillation.

Implanted octacalcium phosphate is more resorbable than beta-tricalcium phosphate and hydroxyapatite

Our previous studies have suggested that synthetic octacalcium phosphate (OCP) could be resorbed and replaced by newly formed bone if implanted in rat skull defects. We hypothesized that the implanted OCP is more resorbable than other commonly used bone graft substitutes of calcium phosphate compounds, such as hydroxyapatite (HA) and beta-tricalcium phosphate (beta-TCP). To test the hypothesis, the present study was designed to compare histomorphometrically resorption of the implanted OCP, HA, and beta-TCP, which were kept in the experimental cranial defect of rats for a long term. A full thickness of standardized trephine defect was made in the rat parietal bone, and the same volume of granules of OCP, HA, and beta-TCP were implanted into the defect. Five specimens of each group were fixed 6 months after implantation. The percentage of remaining implants (r-Imp%) and newly formed bone (n-Bone%) in the defect was analyzed histomorphometrically. The statistical analysis showed that the r-Imp% of OCP was significantly lower than that of HA and beta-TCP. In contrast, the n-Bone% of OCP was significantly higher than that of HA and beta-TCP. The present study has shown that the implanted OCP in the rat cranial defect is more resorbable than the implanted beta-TCP and HA, whereas the implanted OCP enhances bone formation more than the implanted beta-TCP and HA.

Comparison of reliability between the modified groin flap and the forearm flap in oral reconstruction

OBJECTIVE

The groin flap has the advantage of minimum donor-site morbidity, while having the disadvantage of short vascular pedicle of small caliber. Modification of the groin flap has improved the former disadvantage, but the latter one remains. The purpose of this study was to compare the reliability of the modified groin flap with the forearm flap.

STUDY DESIGN

Eleven modified groin flaps and 40 forearm flaps consecutively performed by a single surgeon in a hospital for patients with oral cancer were retrospectively reviewed.

RESULTS

The rate of total flap loss in the modified groin flap group (8.3%) was higher than that in the forearm flap group (2.5%). The rates of partial flap loss in both flaps were similar to those of total flap loss. The failures of the modified groin flap and the forearm flap were due to arterial and venous complications, respectively.

CONCLUSION

The modified groin flap appears to be a little less reliable than is forearm flap; nevertheless, it could be a good option for patients who desire less conspicuous postoperative scars.

Paradoxic abbreviation of repolarization in epicardium of the right ventricular outflow tract during augmentation of Brugada-type ST segment elevation

We report the case of a 53-year-old Japanese man with a typical Brugada-like ECG in whom epicardial and endocardial activation-recovery intervals (ARI) in the right ventricular outflow tract (RVOT) were simultaneously measured by recording unipolar electrograms from the Pathfinder catheter introduced in the great cardiac vein as well as from the multielectrode basket catheter deployed in the RVOT. Epicardial ARI in the RVOT was abbreviated paradoxically at the beat of augmented ST segment elevation in lead V2 after a long pause or after pilsicainide injection. Endocardial ARI in the RVOT and epicardial ARI in the left ventricle were prolonged or were not changed. Our data support the hypothesis that heterogenous response of repolarization across the ventricular wall in the RVOT is responsible for accentuation of ST segment elevation in the right precordial leads.

Implantation of octacalcium phosphate combined with transforming growth factor-beta1 enhances bone repair as well as resorption of the implant in rat skull defects

In our previous study, we reported that synthetic octacalcium phosphate (OCP) enhances bone repair if implanted in rat skull defects. We hypothesized that OCP can be used as an effective carrier for transforming growth factor-beta1 (TGF-beta1) to promote bone repair. We designed the present study to investigate histomorphometrically whether combination with recombinant human TGF-beta1 could promote bone repair caused by OCP per se (Control/OCP). A full-thickness standardized trephine defect was made in the rat parietal bone and OCP combined with recombinant human TGF-beta1 (TGF-beta1/OCP) or Control/OCP was implanted into the defect. Four rats from each group were fixed at 2, 4, and 8 weeks after implantation. Histomorphometrical analysis of the percentage of newly formed bone (n-Bone %) and remaining implants (r-Imp %) in the defect was performed. The statistical analysis showed the n-Bone % of TGF-beta1/OCP was significantly higher than that of the Control/OCP in week 4, whereas the r-Imp % of TGF-beta1/OCP was significantly lower than that of the Control/OCP. The present study demonstrated that OCP can be used as an effective carrier for TGF-beta1 and their combination enhances bone repair as well as resorption of the carrier OCP in the early stage of bone formation.

Acute effects of different atrial pacing sites in patients with atrial fibrillation: comparison of single site and biatrial pacing

It has been reported that a trial single site or biatrial pacing can suppress the occurrence of AF. However, its mechanism remains unclear. The study population included 32 patients with AF (n = 20: AF group), or without paroxysmal AF (n = 12: control group). The mechanism and efficacy of atrial pacing were investigated by electrophysiological studies to determine which was more effective for suppressing AF induction; single site pacing of the right atrial appendage (RAA) or distal coronary sinus (CS-d), or biatrial (simultaneous BAA and CS-d) pacing. In the AF group, AF inducibility was significantly higher with BAA extrastimulus during RAA (12/20; P < 0.0001) or biatrial paced drive (7/20; P < 0.01) than during CS-d paced drive (0/20). In the control group, AF was not induced at any site paced. In the AF group, the conduction delay and other parameters of atrial vulnerability significantly improved during CS-d paced drive. The atrial recovery time (ART) at RAA and CS-d was measured during each basic pacing mode. ART was defined as the sum of the activation time and refractory period, and the difference between ARTs at RAA and CS-d was calculated as the ART difference (ARTD). The ARTD was significantly longer during BAA pacing in the AF group than in control group (155.0 +/- 32.8 vs 128.8 +/- 32.9 ms, P < 0.05). In the AFgroup, ARTDs during biatrial (52.0 +/- 24.2 ms) and CS-d pacing (51.7 +/- 26.0 ms) were significantly shorter than ARTD during RAA pacing. The CS-d paced drive was more effective for suppressing AF induction than biatrial or RAA paced drive by alleviating conduction delay. CS-d and biatrial pacing significantly reduced ARTD compared with RAA pacing.

Implantation of octacalcium phosphate nucleates isolated bone formation in rat skull defects

OBJECTIVE

Our previous radiographic examinations have indicated that the synthetic octacalcium phosphate (OCP) may provide the core for nucleating multiple osteogenic sites in the experimentally created cranial defect.

DESIGN

The present study was designed to confirm the possibility that the implanted OCP causes the osteoinduction as well as the osteoconduction in the rat cranial defect.

MATERIALS AND METHODS

Standardized defects were created in male Wistar rat calvaria, and the OCP granules were implanted into the defect. The sham operated rats were processed in the same way except that nothing was implanted. The rats were fixed at 4 weeks after implantation of OCP or the sham operation. We examined bone formed on the implanted OCP, analyzing serial sections histologically combined with immunohistochemistry for the bone specific protein, osteocalcin.

RESULTS

In the defects treated with OCP, the radiopacity was scattered throughout the defect besides being observed along the defect margin of the parietal bone. Examination of the serial sections showed that some of new bones on the implanted OCP were formed away from the defect margin of the parietal bone with regard to both histological identification and specific molecular marker.

CONCLUSIONS

The present study suggested that the implanted OCP can serve as a core for initiating bone formation and cause the osteoinduction as well as the osteoconduction in the defect.

Localized right ventricular morphological abnormalities detected by electron-beam computed tomography represent arrhythmogenic substrates in patients with the Brugada syndrome

AIMS

This study was designed to determine, using electron-beam CT, whether there are morphological abnormalities in patients with the Brugada syndrome and to elucidate the relationship between those abnormalities and arrhythmogenesis.

METHODS AND RESULTS

Twenty-six consecutive patients with the Brugada syndrome and 23 age- and gender-matched control subjects (controls) were evaluated for morphological abnormalities using electron beam CT. Electron beam CT demonstrated morphological abnormalities of the right ventricle in 21 (81%) of 26 patients, but in only two (9%) of 23 controls. The sites of morphological abnormalities were the right ventricular outflow tract area in 17 patients and the inferior wall of the right ventricle in four patients. Of the seven patients with monoform premature ventricular contractions recorded only in the acute phase, four of the five patients with premature ventricular contractions from the right ventricular outflow tract area had morphological abnormalities in the right ventricular outflow tract area, and the other two patients with premature ventricular contractions from the inferior wall of the right ventricle had morphological abnormalities in the inferior wall of the right ventricle.

CONCLUSION

The sites of morphological abnormalities detected by electron beam CT in patients with the Brugada syndrome were related to the origins of premature ventricular contractions recorded only in the acute phase, which may trigger ventricular fibrillation. These morphological abnormalities may be related to arrhythmogenic substrates in patients with the Brugada syndrome.

Clinical usefulness of a multielectrode basket catheter for idiopathic ventricular tachycardia originating from right ventricular outflow tract

INTRODUCTION

It often is difficult to determine the optimal ablation site for idiopathic ventricular tachycardia (VT) originating from the right ventricular outflow tract (RVOT) when the VT or premature ventricular complex (PVC) does not occur frequently. The aim of our study was to evaluate the usefulness of a multielectrode basket catheter for ablation of idiopathic VT originating from the RVOT.

METHODS AND RESULTS

Radiofrequency (RF) catheter ablation was performed using a 4-mm tip, quadripolar catheter in 50 consecutive patients with 81 VTs originating from the RVOT with (basket group = 25 patients with 45 VTs) or without (control group = 25 patients with 36 VTs) predeployment of a multielectrode basket catheter composed of 64 electrodes. Deployment of the multielectrode basket catheter was possible and safe in all 25 patients in the basket group. Ablation was successful in 25 (100%) of 25 patients in the basket group and in 22 (88%) of 25 patients in the control group. The total number of RF applications and the number of RF applications per PVC morphology did not differ between the two groups. However, both the fluoroscopic and ablation procedure times per PVC morphology were shorter in the basket group than in the control group (36.8+/-14.1 min vs 52.0+/-32.5 min, P = 0.04; 60.0+/-14.6 vs 81.5+/-51.2 min, P = 0.05). This difference was more pronounced in the 29 patients in whom VT or PVC was not frequently observed.

CONCLUSION

The multielectrode basket catheter is safe and useful for determining the optimal ablation site in patients with idiopathic VT originating from the RVOT, especially in those without frequent VT or PVC.