Stability after sagittal split ramus osteotomy without post-operative maxillomandibular fixation in the treatment of prognathic patients with asymmetric mandibles

OBJECTIVE

To examine post-operative stability in prognathic patients with mandibular asymmetry who underwent sagittal split ramus osteotomy (SSRO) of the mandible and titanium screw fixation without post-operative maxillomandibular fixation (MMF).

DESIGN

Skeletal and dental changes after surgery with and without post-operative MMF were compared between prognathic patients with symmetric and asymmetric mandibles.

SETTING AND SAMPLE POPULATION

Second Department of Oral and Maxillofacial Surgery at Tokyo Medical and Dental University. Twenty prognathic patients were examined.

EXPERIMENTAL VARIABLE

An appliance for repositioning the proximal segment was applied in all 20 patients. Ten patients with symmetric mandibles received post-operative MMF with stainless steel wires and intermaxillary rubber traction after the removal of MMF (Group I), while the other 10 patients with asymmetric mandibles underwent post-operative intermaxillary rubber traction only (Group II).

OUTCOME MEASURE

Posteroanterior cephalograms were obtained pre-operatively; 2-3 days post-operatively; and 3, 6, and 12 months after surgery. Changes in the positions of the gonion points (Go) and upper and lower incisors (U-1 and L-1) were examined.

RESULTS

In both groups, the Go tended to shift laterally as a consequence of the operation. Although the tendencies of the post-operative changes in the Go points of Groups II and I were different, statistical analyses revealed no significant differences between the two groups. At the last stage of the follow-up period, the absolute value of the change in L-1 tended to be larger in Group II than in Group I, but without any statistical significance.

CONCLUSION

This study suggests that post-operative change in prognathic patients with asymmetric mandibles treated without post-operative MMF is comparable to that in patients with symmetric mandibles treated with post-operative MMF. Accordingly, post-operative MMF may be avoided, even in prognathic patients with asymmetric mandibles.

[Diagnosis for dental implant using computed tomography and precise implantation using modified stent]

The diagnosis of jaw bones using X-ray computerized tomography is effective to decide the method of implantation, the position of the implant, and the direction for the insertion of the implant. However, it is difficult to apply anatomical information to the superstructures of implants, as well as to prepare implant sockets at the proper site by using an ordinary surgical stent. This would affect the effectiveness of the X-ray computerized tomography considerably. The X-ray computerized tomography with a diagnostic stent has been used in our clinic. CT multiplaner reconstruction images with radiopaque markers are useful to examine the adaptability of implant and to determine an appropriate site of implantation for an ideal prosthesis. Moreover, the diagnostic stent is modified to the surgical stent by drilling guide holes to reproduce a precise direction for inserting implant. By applying this stent, it is possible to reproduce the optimal site and direction for the placement of implant. In this report, two cases, which were treated with diagnosis and the placement of implants by using this technique, were studied. One was a case of overdenture and the other was that of upper anterior prostheses. In both cases, precise implantation was achieved by using this technique.

Telomere length regulation and telomeric chromatin require the nonsense-mediated mRNA decay pathway

Rap1p localization factor 4 (RLF4) is a Saccharomyces cerevisiae gene that was identified in a screen for mutants that affect telomere function and alter the localization of the telomere binding protein Rap1p. In rlf4 mutants, telomeric silencing is reduced and telomere DNA tracts are shorter, indicating that RLF4 is required for both the establishment and/or maintenance of telomeric chromatin and for the control of telomere length. In this paper, we demonstrate that RLF4 is allelic to NMD2/UPF2, a gene required for the nonsense-mediated mRNA decay (NMD) pathway (Y. Cui, K. W. Hagan, S. Zhang, and S. W. Peltz, Mol. Cell. Biol. 9:423-436, 1995, and F. He and A. Jacobson, Genes Dev. 9:437-454, 1995). The NMD pathway, which requires Nmd2p/Rlf4p together with two other proteins, (Upf1p and Upf3p), targets nonsense messages for degradation in the cytoplasm by the exoribonuclease Xrn1p. Deletion of UPF1 and UPF3 caused telomere-associated defects like those caused by rlf4 mutations, implying that the NMD pathway, rather than an NMD-independent function of Nmd2p/Rlf4p, is required for telomere functions. In addition, telomere length regulation required Xrn1p but not Rat1p, a nuclear exoribonuclease with functional similarity to Xrn1p (A. W. Johnson, Mol. Cell. Biol. 17:6122-6130, 1997). In contrast, telomere-associated defects were not observed in pan2, pan3, or pan2 pan3 strains, which are defective in the intrinsic deadenylation-dependent decay of normal (as opposed to nonsense) mRNAs. Thus, loss of the NMD pathway specifically causes defects at telomeres, demonstrating a physiological requirement for the NMD pathway in normal cell functions. We propose a model in which the NMD pathway regulates the levels of specific mRNAs that are important for telomere functions.

[Relationship between aging and morphological bone changes of the condyle in temporomandibular disorders]

In order to clarify the clinical significance of morphological bone changes of the mandibular condyle in temporomandibular disorders, the relationship between radiographic bone changes and aging was clinically studied. The subjects of the study were 1,120 patients (812 females and 308 males). The average age was 33 years +/- 15 years (from 10 to 81 years of age). The 1,120 patients were divided into six age brackets (10 to 19 years, 20 to 29 years, 30 to 39 years, 40 to 49 years, 50 to 59 years, 60 to 81 years). According to radiograms taken by lateral oblique transcranial projection, orbitcondyle projection and orthopantomography, the morphological bone changes were classified into seven groups, erosion, osteophyte, eburnation, flattening, deformity, concavity and sclerosis. The results were as follows: 1. The incidence of the patients with radiographic bone changes of the mandibular condyle increased with aging and showed significantly different age distribution from that without bone changes (Mann-Whitney U test: p < 0.01). 2. The incidence of erosion did not increase with aging and showed significantly different age distribution from osteophyte or eburnation (Mann-Whitney U test: p < 0.01, 0.05). The incidence of flattening also did not increase with aging and showed significantly different age distribution from osteophyte, eburnation or deformity (Mann-Whitney U test: p < 0.01, 0.05, 0.05).

Human slow cortical potential in association with voluntary jaw movements

The distribution of a readiness potential (RP), i.e., a negative-going slow cortical potential (SCP) preceding the onset of voluntary movements, was studied in association with self-paced voluntary jaw-closing and jaw-opening movements in 4 healthy human subjects. A negative-going SCP starting at ca.1.5-2.0 s preceding the onset of the self-paced jaw-opening and jaw-closing movements was found at all the recorded sites of Fz, Cz, Pz, F3, F4, F7, F8, C3, C4, T3 and T4. The RP was maximum in amplitude at Cz (ca.8microV), although there was no significant difference between Cz and either C3 or C4; it was smaller at T3 and T4 than at any of Fz, Cz, Pz, C3, and C4. The polarity, amplitude, and time course of the RP in association with jaw movements was virtually the same as those associated with voluntary unilateral extension of the middle finger, except for a contralaterally-dominant side asymmetry between C3 and C4 in the latter. There was neither rapidly increasing negative potential (NS') in the RP recorded from any site, nor bilateral difference in the RPs coinciding with unilateral biting of a gauze pad. It is suggested that the motor cortex would be activated bilaterally in coordination even in the case of unilateral biting.

Mandibular stability after sagittal split ramus osteotomy without post-operative maxillomandibular fixation in the treatment of prognathic patients with symmetric mandibles

This study was designed to examine post-operative stability in prognathic patients with symmetric lower jaws who underwent sagittal split ramus osteotomy (SSRO) of the mandible without post-operative maxillomandibular fixation (MMF). Twenty prognathic patients with symmetric mandibles were investigated. An appliance for repositioning the proximal segment and titanium screw fixation was applied in all patients. Ten patients underwent post-operative MMF with stainless steel wire (mean duration, 9.6 days) and intermaxillary rubber traction after removal of the MMF (Group I), and the remaining ten underwent intermaxillary rubber traction only (Group II) post-operatively. Cephalograms were obtained 2-3 days post-operatively, and 3, 6, and 12 months after surgery. Changes in the positions of upper incisors (U-1), lower incisors (L-1), B-point, and pogonion were examined on lateral cephalograms. In the early stages of follow-up, decreases in the overbite tended to be more marked in Group I than in Group II, and the forward movement of each standard point was significantly larger in Group I than in Group II. No significant differences, however, were revealed between the two groups at 12 months after surgery. Forward movement of anterior cephalometric landmarks, post-operatively, in Group II were significant, however, this pattern differed from Group I, in which big changes occurred in the early stages after surgery. Although the patterns of post-operative changes in the two groups are different, there are no significant differences in their post-operative stability in long-term follow-up. Therefore, post-operative MMF may be avoided when prognathic patients with symmetric mandibles undergo SSRO with an appliance for repositioning the proximal segment and titanium screw fixation.

Cerebrovascular relaxation responses to endothelium-dependent and -independent vasodilators after normothermic and hypothermic cardiopulmonary bypass in the rabbit

BACKGROUND

Cardiopulmonary bypass causes activation of leukocytes and increased concentrations of proinflammatory mediators, which may result in endothelial dysfunction. Because hypothermia attenuates many inflammatory processes, the authors hypothesized that hypothermic cardiopulmonary bypass would be associated with better endothelial function than normothermic cardiopulmonary bypass.

METHODS

Isoflurane-anesthetized New Zealand White rabbits were randomized to undergo 90 min of either normothermic (37 degrees C, n=9) or hypothermic (27 degrees C, n=9) cardiopulmonary bypass with terminal rewarming. A third group served as anesthetized normothermic non-cardiopulmonary bypass surgical controls (n=8). Basilar artery and descending thoracic aorta were isolated from each animal. In vitro vessel relaxation responses to increasing concentrations of acetylcholine (which induces endothelial release of nitric oxide) and nitroprusside (which provides exogenous nitric oxide) were measured in phenylephrine-precontracted vessel rings.

RESULTS

There were no differences in vessel relaxation responses between normothermic and hypothermic cardiopulmonary bypass groups in basilar artery or aorta. In contrast, basilar arteries from non-cardiopulmonary bypass controls had increased relaxation responses to both acetylcholine (P=0.004) and nitroprusside (P=0.031) compared with the pooled cardiopulmonary bypass animal data.

CONCLUSIONS

The authors observed no differences in endothelial or vascular smooth muscle function between normothermic and hypothermic cardiopulmonary bypass groups. Compared with non-cardiopulmonary bypass controls, cardiopulmonary bypass appeared to decrease basilar artery smooth muscle relaxation in response to endogenous and exogenous nitric oxide.

Vectors for expressing T7 epitope- and His6 affinity-tagged fusion proteins in S. cerevisiae

We have constructed a series of vectors (YGALSETs) for the expression of epitope- and affinity-tagged fusion proteins in yeast cells using the regulated GAL10 promoter. Fusion proteins produced from YGALSET plasmids include a leader peptide at the N terminus that encodes both a T7 gene 10 epitope tag and a His6 affinity tag. The YGALSET vector series includes centromere plasmids for low-copy plasmid maintenance and 2 micron episomal plasmids for multicopy plasmid maintenance and four different selectable markers: TRP1, URA3, LEU2 and HIS3. We also provide a convenient approach for transferring cloned genes from a bacterial expression vector into YGALSET vectors by in vivo recombination and a rapid method to screen directly for clones that express the fusion protein of interest.

[Hemophagocytic syndrome due to miliary tuberculosis in the course of aplastic anemia]

We report a 63 year-old female with aplastic anemia (AA) who was complicated with hemophagocytic syndrome induced by systemic miliary tuberculosis. Two years before admission to our hospital, she was diagnosed as AA and had been treated with granulocyte colony-stimulating factor, erythropoietin and methenolone acetate. In May, 1996, She was transferred to our hospital because of high fever and exacervation of pancytopenia. She showed severe pancytopenia, and an increase in macrophages showing remarkable erythrophagocytosis and decrease in hemopoietic cells in the bone marrow. In initial examination, high titer of IgM antibody to herpes simplex virus type I was identified and methylprednisolone pulse therapy was started under the diagnosis of virus associated hemophagocytic syndrome. Ten days later, however, she died for intestinal hemorrhage followed by multiorgan failure. In autopsy, multiple epitheloid cell granulomas with acid-fast bacilli were found in bone marrow, lungs, liver, spleen and kidneys.

Recovery of evoked potential amplitude after cerebral arterial air embolism in the rabbit: a comparison of the effect of cardiopulmonary bypass with normal circulation

BACKGROUND

Cerebral arterial air embolism (CAAE) may cause neurologic injury during cardiac surgery. It is not known whether cardiopulmonary bypass (CPB) increases or decreases brain injury from CAAE compared with the normal circulation.

METHODS

A model of CAAE was produced by injection of 50 microl/kg air into the internal carotid artery of methohexital-anesthetized New Zealand white rabbits. Somatosensory-evoked potential (SSEP) amplitude was measured serially as a marker of neurologic recovery. In experiment A, saline rather than air was injected to control for surgical manipulation and time in CPB (n = 4) and nonheparinized non-CPB (n = 4) animals. In experiment B, 50 microl/kg air was injected in CPB (n = 11) and nonheparinized non-CPB (n = 11) animals. In experiment C, non-CPB animals (n = 6) were given heparin according to the same protocol as for CPB.

RESULTS

In experiment A, SSEP latencies and amplitudes did not differ between CPB and non-CPB conditions. In experiment B, there was no SSEP recovery 5 min after CAAE in either CPB or non-CPB animals. Thereafter, SSEP recovery was less in CPB animals than in non-CPB animals at 30 min (9 +/- 12% vs. 29 +/- 20%; P = 0.009) and 60 min (18 +/- 15% vs. 39 +/- 22%; P = 0.030) after CAAE. Ninety-minute SSEP recovery did not differ between CPB and non-CPB groups (at 24 +/- 19% vs. 39 +/- 24%, respectively; P = 0.146). In experiment C (heparinized non-CPB), SSEP recovery 5, 30, 60, and 90 min after CAAE was 67 +/- 48%, 72 +/- 47%, 80 +/- 35%, and 77 +/- 35%, respectively.

CONCLUSIONS

Somatosensory-evoked potential recovery after CAAE is no better (and is probably worse) during CPB than during normal circulation. The adverse effect of CPB occurs despite heparinization, which, under non-CPB conditions, appears to be protective. Therapies in addition to heparin are needed during CPB to reduce neurologic injury from CAAE.

Multiple macrodonts with odontoma in a mother and son--a variant of Ekman-Westborg-Julin syndrome. Report of a case

A case of multiple macrodonts with a complex odontoma in a mother and son is reported. This condition is thought to represent a variant of the Ekman-Westborg-Julin syndrome. The authors discuss the relationship between macrodontia and odontoma, and the involvement of hereditary factors is suggested.

Chromatin assembly factor I contributes to the maintenance, but not the re-establishment, of silencing at the yeast silent mating loci

CAC1/RLF2 encodes the largest subunit of chromatin assembly factor I (CAF-I), a complex that assembles newly synthesized histones onto recently replicated DNA in vitro. In vivo, cac1/rlf2 mutants are defective in telomeric silencing and mislocalize Rap1p, a telomere-binding protein. Here, we report that in cells lacking CAF-I the silent mating loci are derepressed partially. MATa cac1 cells exhibit an unusual response to alpha-factor: They arrest and form mating projections (shmoos) initially, but are unable to sustain the arrest state, giving rise to clusters of shmooing cells. cac1 MATa HMLa HMRa strains do not form these shmoo clusters, indicating that derepression of HMLalpha causes the shmoo cluster phenotype in cac1 cells. When SIR3 is reintroduced into sir1 sir3 cells, HML remains derepressed indicating that SIR1 is required for the re-establishment of silencing at HML. In contrast, when SIR3 is reintroduced into cac1 sir3 cells, silencing is restored to HML, indicating that CAF-I is not required for the re-establishment of silencing. Loss of the other CAF-I subunits (Cac2p and Cac3p/Msi1p) also results in the shmoo cluster phenotype, implying that loss of CAF-I activity gives rise to this unstable repression of HML. Strains carrying certain mutations in the amino terminus of histone H4 and strains with limiting amounts of Sir2p or Sir3p also form shmoo clusters, implying that the shmoo cluster phenotype is indicative of defects in maintenance of the structural integrity of silent chromatin. MATa cac- sir1 double mutants have a synergistic mating defect, suggesting that the two silencing mechanisms, establishment and maintenance, function cooperatively. We propose a model to explain the distinctions between the establishment and the maintenance of silent chromatin.

CTLA4 gene polymorphism confers susceptibility to Graves' disease in Japanese

Susceptibility to Graves' disease (GD) is determined by environmental and genetic factors. The genetic susceptibility to GD is conferred by genes in the human leukocyte antigen (HLA), and several other genes unlinked to HLA are thought to contribute to the development of GD. Three recent papers described the association of GD with the CTLA-4 gene. CTLA-4 is a candidate gene for T-cell mediated autoimmune diseases because it is a negative regulator of T-cell proliferation. As CTLA-4 association with GD may be influenced by the racial composition of the population, it is important to study it in other ethnic groups. We investigated the distribution of CTLA-4 gene polymorphism in 153 Japanese patients with GD (35 males and 118 females) and 200 controls (96 males and 104 females). An A/G transition at position 49 of exon 1 was analyzed by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The distribution of genotype frequencies differs between GD and controls (chi2 = 9.46, 2 degrees of freedom, p < 0.01). The presence of at least one G allele (GG or AG) conferred an odds ratio of 2.64 (95% CI = 1.92-3.36). The present study supported the association of the CTLA-4 gene with GD in Japanese and showed that the CTLA4 gene could be one of the non-HLA linked susceptibility genes for GD.

Molecular cloning and characterization of the mouse apoptosis signal-regulating kinase 1

The mouse cDNA for apoptosis signal-regulating kinase 1 (ASK)1 was isolated. The overall amino acid sequence identity between the mouse and the human ASK1 was 91.9%. A database search revealed that the kinase domain of ASK1 is evolutionally well-conserved over species among nematode, fly, mouse and human. Northern blot analysis identified a 6-kb transcript of ASK1 which is expressed in the various mouse adult tissues including heart, brain, lung, liver and kidney. Immunohistochemical analysis of mouse embryos (17 days post coitum) revealed a localized expression of ASK1 in developing skin, cartilage and bone, suggesting a possible role for ASK1 in tissue development during embryogenesis as well as cytokine-induced apoptosis.

Repair of bone defect in primate mandible using a bone morphogenetic protein (BMP)-hydroxyapatite-collagen composite

The purpose of this study was to evaluate a hydroxyapatite (HA)-collagen (Col)-bone morphogenetic protein (BMP) composite as an osteoinductive bone substitute. Partially-purified BMP from bovine bone was mechanically mixed with highly purified type I collagen from calf dermis and then subsequently mixed with pure synthetic hydroxyapatite granules or block. The HA-Col-BMP composite, or the HA-Col composite as a control, was implanted in a surgically-induced mandible bone defect (6 x 7 x 10 mm) in an adult Japanese monkey. The mandible was excised three months after implantation and studied histologically. The BMP-containing implant induced much more new bone than the control implant in all experimental animals of each group, with either HA granules or HA block. Newly formed bone was attached tightly to HA and infiltrated deeply into the pores of the HA of the BMP-containing implant, while fibrous tissue existed between the host bone and HA in the control implant. Thus, we conclude that an HA-Col-BMP composite could be a superior biomaterial for a bone substitute.

Unique behavior of rubidium in mice under low oxygen atmosphere. Simultaneous tracing of Sc, Mn, Fe, Co, Zn, Se, Rb, Y, and Zr using off radioactive multitracer technique

Relative tissue distributions of Sc, Mn, Fe, Co, Zn, Se, Rb, Y, and Zr tracers were studied in young mice housed under four different O2 atmospheres (10 percent, 20 percent, 80 percent, and 100 percent O2) using the radioactive multitracer technique developed at The Institute of Physical and Chemical Research (RIKEN). At 48 hr after injection of the multitracer, the tissue uptake rates were examined for 10 tissues (brain, cardiac muscle, lung, liver, spleen, pancreas, kidneys, skeletal muscle, bone, and blood) and expressed as the radioactivity percentage of the injected dose per gram of wet tissue (percent dose/g). Rubidium uptake rates for all soft tissues of mice housed under a 10 percent O2 atmosphere were found to be higher than those of the tissues of mice housed under the other three O2 atmospheres (20 percent, 80 percent, and 100 percent), but no difference was observed for the other elements (Sc, Mn, Fe, Co, Se, etc.) under any of the O2 atmospheres.