Hiroaki Ishibashi

Autocrine Loop between Vascular Endothelial Growth Factor (VEGF)-C and VEGF Receptor-3 Positively Regulates Tumor-Associated Lymphangiogenesis in Oral Squamoid Cancer Cells

Numerous past studies have suggested a critical role of the paracrine effect between tumor vascular endothelial growth factor (VEGF)-C and lymphatic FLT-4 in solid tumor-associated lymphangiogenesis. In contrast, the pathophysiological role of tumor cell-associated FLT-4 in tumor progression remains to be elucidated. Here, we investigated this role using a tumor implantation model. SAS cells, an oral squamous carcinoma cell line expressing both VEGF-C and FLT-4 but neither FLK-1/KDR nor VEGF-D were adopted for experiments. Stable transformants of dominant-negative (dn) SAS cells were established in which the cytoplasmic domain-deleted FLT-4 was exogenously overexpressed, which can lead to inactivation of endogenous FLT-4 through competitive antagonism and is associated with down-activation of endogenous FLT-4-related intracellular signals. In vitro and in vivo proliferation assays showed lower proliferative activity of dn-SAS cells. An immunohistochemical study revealed that the tumor lymphangiogenesis was significantly suppressed, and the level of human VEGF-C mRNA was significantly lower in dn-SAS cell-derived tumor tissues. Moreover, in vitro studies demonstrated that the significant suppression of VEGF-C and VEGF-A expression was evident in dn-SAS cells or wild-type SAS cells treated with either the FLT-4 kinase inhibitor MAZ51 or the inhibitor of FLT-4-related signals. These findings together suggested that the VEGF-C/FLT-4 autocrine loop in tumor cells was a potential enhancer system to promote cancer progression, and FLT-4 in tumor tissue might become an effective target for cancer therapy.

Oral symptoms including dental erosion in gastroesophageal reflux disease are associated with decreased salivary flow volume and swallowing function

BackgroundThis preliminary clinical study aimed to evaluate the effects of salivary flow volume and swallowing function on oral symptoms including dental erosion in gastroesophageal reflux disease (GERD).MethodsThe subjects were 40 GERD patients and 30 (15 younger, 15 older) healthy controls. Detailed medical, dietary, and dental histories were obtained to identify individual behavioral habits potentially associated with dental erosion. Oral examination evaluated dental erosion and determined scores for the decayed, missing, filled (DMF) index, the papillary, marginal, attached (PMA) index for gingivitis, and the Simplified Oral Hygiene Index (OHI-S). Salivary flow volume and swallowing function were evaluated by the Saxon test and repetitive saliva swallowing test, respectively.ResultsThe DMF index and OHI-S scores differed significantly between all 3 groups. The PMA index was significantly different between the GERD group and the two control groups. The prevalence of dental erosion was 24.3% in the GERD group (0% in the control groups). No specific relationship was found between the incidence of dental erosion and dietary history or behavioral habits. The Saxon test results were significantly lower in the GERD group than in both the control groups. Frequency of swallowing was significantly lower and time to first swallow was significantly longer in the GERD group than in the two control groups.ConclusionsOral symptoms in GERD are likely to be associated with impaired salivary flow volume or swallowing function. Treatment for the oral dryness induced by reduced salivary flow volume and rehabilitation for swallowing function could be indicated in patients with GERD.

Applicability of buccal fat pad grafting for oral reconstruction

This study evaluated the applicability of pedicled buccal fat pad grafting for the reconstruction of defects surgically created during oral surgery. A buccal fat pad graft was applied in 23 patients (5 males, 18 females; mean age 68.3 years) between 2003 and 2011. The graft was used to cover surgical defects of the palate, maxilla, upper gingiva, buccal mucosa, lower gingiva, oral floor, and temporomandibular joint region. Size of the surgical defects ranged from 15mm×12mm to 30mm×40mm; size of the buccal fat pad ranged from 15mm×12mm to 43mm×38mm. A pedicled buccal fat pad was prepared by incising the maxillary vestibule following primary surgery, and the surrounding connective tissue was preserved to supply nutrition to the pedicle during surgery. The buccal fat pad was placed on the raw surface of soft tissue or bone surface and sutured to the surrounding tissue of the defect. Complete epithelialization was observed within 4 weeks postoperatively. There were no complications or functional disorders during follow-up. Buccal fat pad grafting appears to be feasible for the reconstruction of surgically induced defects, and can be extended to the palate, mandible, mouth angle, and temporomandibular joint region.

The retromandibular transparotid approach for reduction and rigid internal fixation using two locking miniplates in mandibular condylar neck fractures

We evaluated the safety, efficacy, and morbidity associated with the treatment of displaced mandibular condylar neck fractures using a retromandibular transparotid approach to reduce and rigidly fix using two 2.0-mm locking miniplates. Our surgical inclusion criteria were: patient selection of open reduction and fixation, displaced unilateral condylar fractures with derangement of occlusion, and bilateral condylar fractures with an anterior open bite. The study group consisted of 19 patients who underwent surgery for 19 mandibular condylar neck fractures; patients were analyzed prospectively, with more than 6 months of follow-up, and were evaluated in terms of functional results, scar formation, postoperative complications, and stability of fixation. The results showed that functional occlusion identical to the preoperative condition and correct anatomical reduction of the condylar segments in centric occlusion, followed by immediate functional recovery, was achieved in all patients. No patient suffered from any major or permanent complication postoperatively, although there were two cases (11%) of temporary facial nerve palsy, which resolved completely within 3 months. Surgical scars were barely visible. The retromandibular transparotid approach with open reduction and rigid internal fixation for displaced condylar neck fractures of the mandible is a feasible and safe, minimally invasive surgical technique that provides reliable clinical results.

Upregulation of aquaporin expression in the salivary glands of heat-acclimated rats

It is known that aquaporin (AQP) 5 expression in the apical membrane of acinar cells in salivary glands is important for the secretion of saliva in rodents and humans. Although heat acclimation enhances saliva secretion in rodents, the molecular mechanism of how heat induces saliva secretion has not been determined. Here, we found that heat acclimation enhanced the expression of AQP5 and AQP1 in rat submandibular glands concomitant with the promotion of the HIF-1α pathway, leading to VEGF induction and CD31-positive angiogenesis. The apical membrane distribution of AQP5 in serous acinar cells enhanced after heat acclimation, while AQP1 expression was restricted to the endothelial cells in the submandibular glands. A network of AQPs may be involved in heat-acclimated regulation in saliva secretion. Because AQPs probably plays a crucial role in saliva secretion in humans, these findings may lead to a novel strategy for treating saliva hyposecretion.

Effects of transforming growth factor beta 1 on the plasminogen activation system, collagen and integrin synthesis, and proliferation of rabbit mandibular condylar chondrocytes

The objective of this study was to identify the mechanism by which mandibular condyle chondrocytes regulate the extracellular matrix. Primary rabbit condylar chondrocytes were isolated, cultured, and treated with transforming growth factor beta 1 (TGF-β1). Cells were then assayed for the following: urokinase-type plasminogen activator (uPA) and its inhibitor (PAI-1), collagen types I and II, β1 integrin expression, and proliferative activity. TGF-β1 induced synthesis of collagen type II, αVβ1 integrin, and PAI-1. TGF-β1 induced the growth of chondrocytes and suppressed the synthesis of uPA. Chondrocyte regulation of the extracellular matrix is mediated by TGF-β1. Synthesis of collagen type II, αVβ1 integrin, and PAI-1 is induced, while uPA is suppressed. Also, TGF-β1 induces cellular growth.

Simultaneous Sinus Lifting and Alveolar Distraction of a Severely Atrophic Posterior Maxilla for Oral Rehabilitation with Dental Implants

We retrospectively reviewed a new preimplantation regenerative augmentation technique for a severely atrophic posterior maxilla using sinus lifting with simultaneous alveolar distraction, together with long-term oral rehabilitation with implants. We also analyzed the regenerated bone histomorphologically. This study included 25 maxillary sinus sites in 17 patients. The technique consisted of alveolar osteotomy combined with simultaneous sinus lifting. After sufficient sinus lifting, a track-type vertical alveolar distractor was placed. Following a latent period, patient self-distraction was started. After the required augmentation was achieved, the distractor was left in place to allow consolidation. The distractor was then removed, and osseointegrated implants (average of 3.2 implants per sinus site, 80 implants) were placed. Bone for histomorphometric analysis was sampled from six patients and compared with samples collected after sinus lifting alone as controls (n = 4). A sufficient alveolus was regenerated, and all patients achieved stable oral rehabilitation. The implant survival rate was 96.3% (77/80) after an average postloading followup of 47.5 months. Good bone regeneration was observed in a morphological study, with no significant difference in the rate of bone formation compared with control samples. This new regenerative technique could be a useful option for a severely atrophic maxilla requiring implant rehabilitation.

Surgical treatment of comminuted mandibular fractures using a low-profile locking mandibular reconstruction plate system.

Objective: The treatment of comminuted mandibular fractures is challenging due to the severity of associated injuries and the need for a careful diagnosis with adequate treatment planning. Recently, open reduction and stable internal fixation (OR-IF) with a load-bearing reconstruction plate have been advocated for reliable clinical outcomes with minimal complications. This clinical prospective study evaluated OR-IF in the surgical management of comminuted mandibular fractures with a new low-profile, thin, mandibular locking reconstruction plate. Materials and Methods: We prospectively assessed OR-IF of comminuted mandibular fractures with a low-profile locking mandibular reconstruction plate in 12 patients (nine men, three women; mean age 32.2 [range 16-71] years) between April 2010 and December 2011. The clinical characteristics and associated clinical parameters of patients were evaluated over a minimum follow-up period of 12 months. Results: Traffic accidents caused 50% of the fractures, followed by falls (25%). Four patients (33.3%) had associated midfacial maxillofacial fractures, while five patients had other mandibular fractures. Seven patients (58.3%) needed emergency surgery, mostly for airway management. Anatomical reduction of the comminuted segments re-established the mandibular skeleton in stable occlusion with rigid IF via extraoral (33.3%), intraoral (50%), or combined (16.7%) approaches. Immediate functional recovery was achieved. Sound bone healing was confirmed in all patients, with no complications such as malocclusion, surgical site infection, or malunion with a mean follow-up of 16.3 (range 12-24) months. Conclusions: OR-IF using a low-profile reconstruction plate system is a reliable treatment for comminuted mandibular fractures, enabling immediate functional recovery with good clinical results.

Transfection of hypoxia-inducible factor-1 decoy oligodeoxynucleotides suppresses expression of vascular endothelial growth factor in oral squamous cell carcinoma cells.

Vasculature development is thought to be an important aspect in the growth and metastasis of solid tumors. Among the many angiogenic factors produced by tumor cells, vascular endothelial growth factor (VEGF) is considered to play a key role in angiogenic processes. VEGF synthesis is modulated by hypoxia-inducible factor-1 (HIF-1) function within the hypoxic microenvironment of growing cancer tissue. To inhibit HIF-1 activation, oligodeoxynucleotides (ODNs) were synthesized and transferred with either the consensus sequence for HIF-1 binding or a mutated form of this sequence. If we could transfer a large number of ODNs into the cancer cell nucleus, activated HIF-1 might bind to the ODNs, resulting in inhibition of hypoxia-induced VEGF synthesis. We transferred these ODNs into cultured oral squamous cell carcinoma cells (SAS cells) using the hemagglutinating virus of Japan (HVJ)-liposome method. Hypoxia-mediated expression of VEGF by cancer cells was suppressed by transfection of HIF-1 decoy ODNs, but not by mutated HIF-1 decoy ODNs. HIF-1 decoy ODN transfection also inhibited VEGF protein synthesis. These results suggest that transfection with HIF-1 decoy ODNs is effective for regulating tumor growth by reducing VEGF.

Maxillary Verrucous Carcinoma Coincident With Cervical Lymph Node Metastasis of Colon Adenocarcinoma

Cervical lymph node metastasis is an extremely rare event in oral verrucous carcinoma. Isolated cervical lymph node metastasis of colon cancer is also rare. This article describes a case of maxillary verrucous carcinoma accompanied by colon adenocarcinoma that metastasized to a cervical lymph node in a 69-year-old Japanese woman. During preoperative evaluation for maxillary verrucous carcinoma, enlarged cervical lymph nodes and colon cancer were suspected by positron emission tomography. Colonoscopy with biopsies confirmed primary colon adenocarcinoma. Left radical neck dissection, partial maxillectomy, and full-thickness skin graft to the mucosa of the upper lip were performed before treatment of colon adenocarcinoma. Cervical lymph nodes showed metastasis from colon adenocarcinoma, and right hemicolectomy was performed. This is the first case report of synchronous oral verrucous carcinoma and colon adenocarcinoma with cervical lymph node metastasis.