Three-dimensional finite element model to predict patterns of pterygomaxillary dysjunction during Le Fort I osteotomy.

The aim of this study was to determine whether non-linear three-dimensional finite element analysis (3D-FEA) can be applied to simulate pterygomaxillary dysjunction during Le Fort I osteotomy (LFI) not involving a curved osteotome (LFI-non-COSep), and to predict potential changes in the fracture pattern associated with extending the cutting line. Computed tomography (CT) image data (100 snapshots) after LFI were converted to 3D-CT images. 3D-FEA models were built using preoperative CT matrix data and used to simulate pterygomaxillary dysjunction. The pterygomaxillary dysjunction patterns predicted by the 3D-FEA models of pterygomaxillary dysjunction were classified into three categories and compared to the pterygomaxillary dysjunction patterns observed in the postoperative 3D-CT images. Extension of the cutting line was also simulated using the 3D-FEA models to predict the risk and position of pterygoid process fracture. The rate of agreement between the predicted pterygomaxillary dysjunction patterns and those observed in the postoperative 3D-CT images was 87.0% (κ coefficient 0.79). The predicted incidence of pterygoid process fracture was higher for cutting lines that extended to the pterygomaxillary junction than for conventional cutting lines (odds ratio 4.75; P<0.0001). 3D-FEA can be used to predict pterygomaxillary dysjunction patterns during LFI-non-COSep and provides useful information for selecting safer procedures during LFI-non-COSep.

Prediction of neurosensory alterations after sagittal split ramus osteotomy.

Prediction of neurosensory deficit in the lower lip and chin after sagittal split ramus osteotomy (SSRO) is challenging. This study aimed to elucidate factors related to the development and improvement of neurosensory disturbance (NSD) after SSRO with respect to surgical procedure and the anatomical and structural characteristics of the craniomaxillofacial skeleton. Subjects comprised 50 patients treated by a single experienced surgeon. Anatomical data and landmarks were obtained by computed tomography (CT) imaging. There was a significant difference between patients with or without NSD for the surgical space on the medial side of mandibular ramus 1 week after SSRO (P=0.006). Less than 15.0mm between the lingula and mandibular notch (relative risk, 6.7; 95% CI, 1.7-33.8) and 195.0mm(2) or more space on the medial side of the mandibular ramus (relative risk, 17.2; 95% CI, 3.9-100.4) indicated a significant risk of NSD development at 6 months postoperatively. These results suggested that the development of NSD is related to the surgical space on the medial side of the mandibular ramus and subsequent manipulation of the inferior alveolar nerve (IAN) in that region. Limited periosteal degloving prevents excessive stretching of the IAN during SSRO, thus lowering NSD incidence.

Risk of surgical glove perforation in oral and maxillofacial surgery.

Oral and maxillofacial surgery, which involves several sharp instruments and fixation materials, is consistently at a high risk for cross-contamination due to perforated gloves, but it is unclear how often such perforations occur. This study aimed to address this issue. The frequency of the perforation of surgical gloves (n=1436) in 150 oral and maxillofacial surgeries including orthognathic surgery (n=45) was assessed by the hydroinsufflation technique. Orthognathic surgery had the highest perforation rate in at least 1 glove in 1 operation (91.1%), followed by cleft lip and palate surgery (55.0%), excision of oral soft tumour (54.5%) and dental implantation (50.0%). The perforation rate in scrub nurses was 63.4%, followed by 44.4% in surgeons and first assistants, and 16.3% in second assistants. The odds ratio for the perforation rate in orthognathic surgery versus other surgeries was 16.0 (95% confidence interval: 5.3-48.0). The protection rate offered by double gloving in orthognathic surgery was 95.2%. These results suggest that, regardless of the surgical duration and blood loss in all fields of surgery, orthognathic surgery must be categorized in the highest risk group for glove perforation, following gynaecological and open lung surgery, due to the involvement of sharp objects.

Novel SR-protein-specific kinase, SRPK2, disassembles nuclear speckles.

SR-protein-specific kinase 1 (SRPK1) is first identified as a specific kinase for SR splicing factors. By RT-PCR of a conserved kinase domain, novel SR-protein-specific kinase clones were isolated from mouse brain. The cloned cDNAs encode a 106 kDa protein (648 amino acids, 92% identical to human SRPK1) and a 120 kDa protein (681 amino acids, 58% identical to human SRPK1). Therefore, they were designated mSRPK1 and mSRPK2, respectively. Northern blotting revealed the ubiquitous expression of mSRPK1 in all tissues examined and the tissue-specific expression of mSRPK2 in testis, lung, and brain. Both kinases phosphorylated SF2/ASF, a member of SR proteins in vitro and the phosphopeptide mappings were identical, indicating that these kinases phosphorylate the same site of SF2/ASF. Overexpression of mSRPK2 caused disassembly of cotransfected SF2/ASF and endogenous SC35. Our results indicate that SRPK family members may regulate the disassembly of the SR proteins in a tissue-specific manner.

Human astrocytoma cells (U-87 MG) exhibit a specific substance P binding site with the characteristics of an NK-1 receptor.

To investigate substance P (SP) receptors on an established human astrocytoma cell line (U-87 MG), [3H][Sar9,Met(O2)11]-SP, a selective SP receptor agonist, was used to identify and characterize the cell membrane binding sites for SP. SP receptor mRNA was examined by solution hybridization analysis, and the existence of SP binding protein on the surface of membranes was evaluated by flow cytometry using an anti-SP binding protein antibody. In U-87 MG and U-373 MG RNA preparations, transcripts were identified that corresponded to both mature and partially spliced receptor forms. In U-87 MG cell membrane-enriched preparations, the binding of [3H][Sar9,Met(O2)11]-SP was found to be time and cell number dependent, specific, saturable, and of high affinity. Equilibrium binding analysis revealed a single class of binding sites with an apparent KD of 1.15 +/- 0.15 nM and a Bmax of 108 +/- 9.8 fmol/mg of protein. [3H][Sar9, Met(O2)11]-SP binding was basically not influenced by addition of mono (Na+, Li+) or divalent (Mg2+, Mn2+, Ca2+) cations; only high doses of divalent cations decreased the binding. GTP and guanylyl-5'-imidodiphosphate, but not GDP and GMP, reduced the Bmax without changing the affinity of [3H][Sar9,Met(O2)11]-SP. We also examined the effects of pretreatment with three lectins [concanavalin A (con A), wheat germ agglutinin (WGA), and Lens culinaris agglutinin (LCA)] to determine the nature of carbohydrate chains on the U-87 MG cell. Of three lectins analyzed for effects on agonist binding, WGA and LCA had an inhibitory effect, whereas con A was ineffective. These results suggest that SP receptors on the human astrocytoma cell line U-87 MG have either a biantennary complex-type or a high mannose-type of carbohydrate chain and may be regulated by GTP-binding protein(s).

Purification and identification of a major activator for p38 from osmotically shocked cells. Activation of mitogen-activated protein kinase kinase 6 by osmotic shock, tumor necrosis factor-alpha, and H2O2.

A stress-activated, serine/threonine kinase, p38 (also known as HOG1 or MPK2) belongs to a subgroup of mitogen-activated protein kinase (MAPK) superfamily molecules. An activity to activate p38 (p38 activator activity) as well as p38 activity itself were greatly stimulated by hyperosmolar media in mouse lymphoma L5178Y cells. The activator activity has been purified by sequential chromatography. A 36-kDa polypeptide that was coeluted with the activity in the final chromatography step was identified as MAPK kinase 6 (MAPKK6) by protein microsequencing analysis. Monoclonal and polyclonal antibodies raised against recombinant MAPKK6 recognized specifically the 36-kDa MAPKK6 protein but did not cross-react with MKK3 proteins. The use of these anti-MAPKK6 antibodies revealed that two major peaks of the p38 activator activity in the first chromatography step reside in the activated MAPKK6. Using a genetic screen in yeast, we isolated MKK3b, an alternatively spliced form of MKK3. Like MKK3 and MAPKK6, MKK3b was shown to be a specific activator for p38 and was activated by osmotic shock when expressed in COS7 cells. Immunoblotting analysis revealed that MAPKK6 is expressed highly in HeLa and KB cells and scarcely in PC12 cells, whereas MKK3 and MKK3b are expressed in all cells examined. Immunodepletion of MAPKK6 from the extracts obtained from L5178Y cells and KB cells exposed to hyperosmolar media depleted them of almost all of the p38 activator activity, indicating that MAPKK6 is a major activator for p38 in an osmosensing pathway in these cells. In addition, MAPKK6 was activated strongly by tumor necrosis factor-alpha, H2O2, and okadaic acid and moderately by cycloheximide in KB cells. Thus, there are at least three members of p38 activator, MKK3, MKK3b, and MAPKK6, and MAPKK6 may function as a major activator for p38 when expressed.

A novel kinase cascade mediated by mitogen-activated protein kinase kinase 6 and MKK3.

A cDNA encoding a novel member of the mitogen-activated protein kinase kinase (MAPKK) family, MAPKK6, was isolated and found to encode a protein of 334 amino acids, with a calculated molecular mass of 37 kDa that is 79% identical to MKK3. MAPKK6 was shown to phosphorylate and specifically activate the p38/MPK2 subgroup of the mitogen-activated protein kinase superfamily and could be demonstrated to be phosphorylated and activated in vitro by TAK1, a recently identified MAPKK kinase. MKK3 was also shown to be a good substrate for TAK1 in vitro. Furthermore, when co-expressed with TAK1 in cells in culture, both MAPKK6 and MKK3 were strongly activated. In addition, co-expression of TAK1 and p38/MPK2 in cells resulted in activation of p38/MPK2. These results indicate the existence of a novel kinase cascade consisting of TAK1, MAPKK6/MKK3, and p38/MPK2.

Isolation of substance P binding protein from rat brain.

Substance P (SP) binding protein of rat brain was solubilized by digitonin. The solubilized proteins were then purified by sequential gel filtration, concanavalin A lectin Sepharose, and SP-affinity chromatography. The calculated molecular weight of this purified SP binding protein was 76-74 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The rabbits were immunized with the purified protein and resulting polyclonal anti-sera were tested. The immune serum significantly inhibited [3H]SP binding to the 3-[(3-cholamidopropyl)dimethylammonio]-1-propane sulfonate solubilized membrane fractions from rat brain, whereas pre-bleed antiserum failed to inhibit the binding. This polyclonal antibody also inhibited the activity of 45Ca influx into astroglioma cells stimulated by SP, but does not inhibit that stimulated by histamine. Furthermore, this polyclonal antibody recognized the 76-74 kDa band as assessed by Western blotting. These data strongly suggest that this polyclonal antibody could recognize a part of the natural SP receptor site.