Hoarseness as the first symptom in a patient with acute suppurative thyroiditis secondary to a pyriform sinus fistula: a case report.

BACKGROUND: Pyriform sinus fistulas (PSFs) are rare congenital anomalies of the third or fourth brachial pouch. Dyspnea is reportedly secondary to compression by a neck mass. However, hoarseness, as the first symptom of PSF, has not yet been reported. CASE PRESENTATION: This report describes an 11-year-old girl presenting with hoarseness as the first symptom of PSF. Hoarseness occurred 2 days prior to admission. On admission, she had fever, hoarseness, and an elastic soft mass on her left anterior neck. Contrast-enhanced computed tomography of the cervical region demonstrated an abscess partially infiltrating the thyroid gland and an air pocket near the pyriform sinus. Pharyngoscopy revealed swelling of the left arytenoid region, with purulent retention. The left vocal cord was swollen but not paralyzed. Additionally, the laboratory data indicated thyrotoxicosis. Suspecting a PSF infection, parenteral treatment with cefotaxime and dexamethasone was initiated. On the following day, the hoarseness disappeared, and the fever resolved. Four weeks after onset, the thyroid hormone levels returned to the normal range, and a barium esophagogram revealed residual contrast in the left pyriform sinus, leading to a diagnosis of PSF. CONCLUSION: PSF presenting with hoarseness as the first symptom in patients should be considered.

Intratumoral delivery of an HPV vaccine elicits a broad anti-tumor immune response that translates into a potent anti-tumor effect in a preclinical murine HPV model.

Therapeutic cancer vaccines have met limited clinical success. In the setting of cancer, the immune system is either tolerized and/or has a limited tumor-specific T cell repertoire. In this study, we explore whether intratumoral (IT) vaccination with an HPV vaccine can elicit quantitative and qualitative differences in immune response as compared to intramuscular (IM) vaccination to overcome immune resistance in established tumors. We report that IT administration of an HPV-16 E7 peptide vaccine formulated with polyinosinic-polycytidylic acid [poly(I:C)] generated an enhanced antitumor effect relative to IM delivery. The elicited anti-tumor effect with IT vaccination was consistent among the vaccinated groups and across various C57BL/6 substrains. IT vaccination resulted in an increased frequency of PD-1hi TILs, which represented both vaccine-targeted and non-vaccine-targeted tumor-specific CD8+ T cells. Overall, the CD8+/Treg ratio was increased within the tumor microenvironment using IT vaccination. We also assessed transcriptional changes in several immune-related genes in the tumor microenvironment of the various treated groups, and our data suggest that IT vaccination leads to upregulation of a broad complement of immunomodulatory genes, including upregulation of interferon gamma (IFNγ) and antigen presentation and processing machine (APM) components. IT vaccine delivery is superior to traditional IM vaccination routes with the potential to improve tumor immunogenicity, which has potential clinical application in the setting of accessible lesions such as head and neck squamous cell carcinomas (HNSCCs).

Clinical utility of dynamic-enhanced MRI in salivary gland tumors: retrospective study and literature review.

PURPOSE: To improve the diagnoses of the salivary gland tumors, a dynamic-enhanced MRI (dMRI) was investigated. METHODS: We conducted a retrospective chart review of 93 cases of salivary gland tumors. The histological diagnoses were obtained from all patients using a surgical specimen and/or an open biopsy specimen. The dMRI as well as fine-needle aspiration cytology (FNAC) and intraoperative frozen section (IFS) were analyzed. This study focused on the time-intensity curve (TIC) after injection, peak time (Tpeak), washout ratio (WR) as well as the gradient of enhancement and washout profile. RESULTS: The histological diagnoses included pleomorphic adenoma (PMA) in 53 cases, the Warthin tumors (WT) in 14 cases and malignant tumors (MT) in 26 cases. Incorrect diagnosis rate of FNAC and IFS were 5.2 and 8.3%, respectively. The TIC revealed differences among the three types of tumors. Tpeak as well as WR also revealed significant differences (p < 0.001). Tpeak were lower in order of WT, MT, PMA, respectively. WR of TICs at 30, 45 and 105 s after Tpeak were higher in order of WT, MT, PMA, respectively (p < 0.001). The gradient of increment and washout in the TIC curve was also an important parameter to distinguish the three types of tumors. In MT, the rapid enhancement pattern was found in high or intermediate histological grade tumors, whereas the slow enhancement pattern was exhibited in low grade tumors. CONCLUSIONS: Our findings indicate that using Tpeak and WR, it is possible to distinguish between WT, PMA and MT. Additionally, a rapid enhancement pattern may be a potential marker for these tumors.

Amorphous-Si waveguide on a garnet magneto-optical isolator with a TE mode nonreciprocal phase shift.

We fabricated a magneto-optical (MO) isolator with a TE mode nonreciprocal phase shift. The isolator is based on a Mach-Zehnder interferometer composed of 3-dB directional couplers, a reciprocal phase shifter, and a nonreciprocal phase shifter. To realize TE mode operation in the optical isolator, we designed a novel waveguide structure composed of a hydrogenated amorphous silicon waveguide with an asymmetric MO garnet lateral clad on a garnet substrate. The isolator operation is successfully demonstrated in a fabricated device showing the different transmittances between forward and backward directions. The maximum isolation of the fabricated isolator is 17.9 dB at a wavelength of 1561 nm for the TE mode.

Identification of the murine H-2D(b) and human HLA-A*0201 MHC class I-restricted HPV6 E7-specific cytotoxic T lymphocyte epitopes.

Recurrent respiratory papillomatosis is caused by human papillomavirus (HPV) infection, most commonly types 6 (HPV-6) and 11 (HPV-11). Due to failed host immune responses, HPV is unable to be cleared from the host, resulting in recurrent growth of HPV-related lesions that can obstruct the lumen of the airway within the upper aerodigestive tract. In our murine model, the HPV-6b and HPV-11 E7 antigens are not innately immunogenic. In order to enhance the host immune responses against the HPV E7 antigen, we linked calreticulin (CRT) to HPV-6b E7 and found that vaccinating C57BL/6 mice with the HPV-6b CRT/E7 DNA vaccine is able to induce a CD8+ T cell response that recognizes an H-2D(b)-restricted E7aa21-29 epitope. Additionally, vaccination of HLA-A*0201 transgenic mice with HPV-6b CRT/E7 DNA generated a CD8+ T cell response against the E7aa82-90 epitope that was not observed in the wild-type C57BL/6 mice, indicating this T cell response is restricted to HLA-A*0201. In vivo cytotoxic T cell killing assays demonstrated that the vaccine-induced CD8+ T cells are able to efficiently kill target cells. Interestingly, the H-2D(b)-restricted E7aa21-29 sequence and the HLA-A*0201-restricted E7aa82-90 sequence are conserved between HPV-6b and HPV-11 and may represent shared immunogenic epitopes. The identification of the HPV-6b/HPV-11 CD8+ T cell epitopes facilitates the evaluation of various immunomodulatory strategies in preclinical models. More importantly, the identified HLA-A*0201-restricted T cell epitope may serve as a peptide vaccination strategy, as well as facilitate the monitoring of vaccine-induced HPV-specific immunologic responses in future human clinical trials.

Effect of HMB/Arg/Gln on the prevention of radiation dermatitis in head and neck cancer patients treated with concurrent chemoradiotherapy.

OBJECTIVE: This prospective randomized Phase II study was designed to evaluate the preventive effect of an oral nutrition supplement composed of beta-hydroxy-beta-methylbutyrate, arginine and glutamine (beta-hydroxy-beta-methylbutyrate/arginine/glutamine) on radiation dermatitis in head and neck cancer patients. METHODS: Forty patients with histologically proven head and neck cancer, treated with concurrent chemoradiotherapy involving cisplatin were recruited. They were randomly assigned to the beta-hydroxy-beta-methylbutyrate/arginine/glutamine supplement treatment group (Group A) or the control group that received no supplement (Group B). The primary endpoint of this study was the percentage of patients developing ≥Grade 3 dermatitis. The secondary endpoints were the percentage of patients developing ≥Grade 2 dermatitis, and the duration of each grade of dermatitis relative to the observation period. RESULTS: The incidence of ≥Grade 3 dermatitis did not differ between the two groups. However, as secondary endpoints of this study, the incidence of ≥Grade 2 dermatitis was lower in Group A than B (62.6 vs. 94.4%; P < 0.05), and the duration of ≥Grade 1 dermatitis was shorter in Group A than B (44.8 vs. 56.7%; P < 0.01), as was the duration of ≥Grade 2 dermatitis (16.5 vs. 26.5%; P < 0.05). CONCLUSIONS: Our study indicated that beta-hydroxy-beta-methylbutyrate/arginine/glutamine supplementation was potentially effective in the prevention of radiation dermatitis in head and neck cancer patients.

Unusual parapharyngeal extension of peritonsillar abscess to the masticator space: successfully drained by extraoral and intraoral endoscopic approaches.

OBJECTIVE: The object was to describe 2 novel cases of peritonsillar abscess showing peculiar extension to the masticator space. METHODS: The methods included clinical case records, including computed tomography and surgical approaches. RESULTS: Both patients we encountered were suffering from systematic diseases, with case 1 involving a 75-year-old man with diabetes mellitus and case 2 involving a 90-year-old woman taking immunosuppressive medications. The abscesses were peritonsillar in origin, extending primarily to the parapharyngeal space, with unusual secondary extension to the masticator space. Extraoral drainage conducted in case 1 was useful for assessing the masticator space and surrounding spaces, but endoscopy-assisted intraoral drainage in case 2 was less invasive, obviating the need for identifying the facial nerve. CONCLUSIONS: It is important to bear in mind that patients suffering from systemic diseases may display unusual extension of deep head and neck infections, and enhanced computed tomography is a useful modality for evaluating such extensions.

Carboxymethyldextran/magnetite hybrid microspheres designed for hyperthermia.

Recently, organic-inorganic hybrids composed of derivatives of dextran, a polysaccharide, and magnetite nanoparticles have attracted much attention as novel thermoseeds. If they can be fabricated into microspheres of size 20-30 µm, they are expected to show not only hyperthermia effects but also embolization effects in human liver and kidney cancers. In this study, we examined the fabrication of carboxymethyldextran/magnetite microspheres using a water/oil emulsion as the reaction medium. Improvement of the chemical stability of the microcapsules by coating with silica using a sol-gel process was also investigated. The obtained hollow microspheres contained particles of size 20-30 µm. Silica coating using an appropriate catalyst for hydrolysis and polycondensation of alkoxysilanes was found to be effective for preventing dissolution and collapse in simulated body environments.

Case report of Mammary Analog Secretory Carcinoma of the parotid gland.

Mammary Analog Secretory Carcinoma (MASC) is a new entity of malignant salivary gland tumors that morphologically resembles mammary secretory carcinoma and carries the identical ETV6-NTRK3 fusion gene. We report our first case of MASC in Japan occurring in the parotid gland of a 37-year-old female patient with a t (12; 15) (p13; q25) translocation. Histologically, the tumor was composed of monomorphic cuboidal cells with low-grade vesicular nuclei and pale eosinophilic cytoplasm, and formed microcystic and tubular spaces with periodic acid-Schiff-positive secretion. Immunohistochemically, the tumor cells tested positive for cytokeratin, vimentin, and S-100 protein. MASC is a morphological mimicker of acinic cell carcinoma, but is a distinct neoplasm characterized by a specific chromosomal translocation. An accumulation of similar case studies is mandatory in order to clarify biological behaviors.

Recurrence of Lymph Node Micrometastases After Radiotherapy for Head and Neck Carcinoma: A Propensity Score-matched Study.

Background: The standard irradiation dose to the elective lymph node area (ELNA) in locally patients with advanced head and neck squamous cell carcinoma (LA-HNSCC) to control lymph node micrometastases (LN-MM) has not changed since it was empirically determined in the 1950s. We investigated the optimal irradiation dose for controlling LN-MM in ELNAs. Patients and Methods: The pattern of recurrence of LA-HNSCC was retrospectively evaluated in patients who underwent concurrent chemoradiotherapy with cisplatin or radiation therapy alone. Results: In total, 162 patients were enrolled. The median observation period was 34 months. No recurrence was found in ELNAs. After propensity score matching, a cisplatin dose of ≥200 mg/m 2 yielded a significantly higher overall survival rate (p≤0.001) and locoregional control rate (p=0.034) than did a dose of <100 mg/m 2 . Conclusion: CCRT with a cisplatin dose of ≥200 mg/m 2 can reduce the irradiation dose to 40-44 Gy at 2 Gy per fraction to control LN-MM.

Characteristics of aspiration pneumonia patients in acute care hospitals: A multicenter, retrospective survey in Northern Japan.

BACKGROUND: Pneumonia is a common cause of illness and death of the elderly in Japan. Its prevalence is escalating globally with the aging of population. To describe the latest trends in pneumonia hospitalizations, especially aspiration pneumonia (AP) cases, we assessed the clinical records of pneumonia patients admitted to core acute care hospitals in Miyagi prefecture, Japan. METHODS: A retrospective multi-institutional joint research was conducted for hospitalized pneumonia patients aged ≥20 years from January 2019 to December 2019. Clinical data of patients were collected from the medical records of eight acute care hospitals. RESULTS: Out of the 1,800 patients included in this study, 79% of the hospitalized pneumonia patients were aged above 70 years. The most common age group was in the 80s. The ratio of AP to total pneumonia cases increased with age, and 692 out of 1,800 patients had AP. In univariate analysis, these patients had significantly older ages, lower body mass index (BMI), a lower ratio of normal diet intake and homestay before hospitalization, along with more AP recurrences and comorbidities. During hospitalization, AP patients had extended fasting periods, more swallowing assessments and interventions, longer hospitalization, and higher in-hospital mortality rate than non-AP patients. A total of 7% and 2% AP patients underwent video endoscopy and video fluorography respectively. In multivariate analysis, lower BMI, lower C-reactive protein, a lower ratio of homestay before hospitalization, a higher complication rate of cerebrovascular disease, dementia, and neuromuscular disease were noted as a characteristic of AP patients. Swallowing interventions were performed for 51% of the AP patients who had been hospitalized for more than two weeks. In univariate analysis, swallowing intervention improved in-hospital mortality. Lower AP recurrence before hospitalization and a lower ratio of homestay before hospitalization were indicated as characteristics of AP patients of the swallowing intervention group from multivariate analysis. Change in dietary pattern from normal to modified diet was observed more frequently in the swallowing intervention group. CONCLUSION: AP accounts for 38.4% of all pneumonia cases in acute care hospitals in Northern Japan. The use of swallowing evaluations and interventions, which may reduce the risk of dysphagia and may associate with lowering mortality in AP patients, is still not widespread.

Parotid secretory carcinoma with high-grade transformation.

Here we present a patient with a parotid secretory carcinoma (SC) with high-grade transformation. A 65-year-old female was referred to our hospital due to a gradually growing right parotid tumor discovered initially about 4 years earlier. MRI imaging detected a right parotid tumor 50 mm in the longer axis. Fine needle aspiration cytology indicated a class III tumor. Nine months after her initial visit, she revisited our department because of pain, trismus and facial paralysis. MRI detected a tumor 69 mm in the longer axis and 64 mm in the shorter axis and a biopsy specimen revealed parotid cancer. Furthermore, positron emission tomography revealed a synchronous small cell lung cancer (SCLC). Chemoradiotherapy for the SCLC was performed followed by an extended total parotidectomy for the parotid SC. Histological findings and ETV6-FISH analysis confirmed a parotid SC with high-grade transformation. Two months after the surgery, CT revealed a loco-regional recurrence and proton beam therapy (70.2 GyE/26 Fr) was performed. Three months after the proton beam therapy, CT indicated pleural effusion and lung metastasis, and fine needle aspiration cytology revealed the metastatic SC. Eight months after the surgery, the patient died due to the lung metastasis of SC.

Management of adenoid cystic carcinoma of the head and neck: a single-institute study with over 25-year follow-up.

BACKGROUND: Adenoid cystic carcinoma is a rare malignant tumor arising from exocrine glands such as the major and minor salivary glands of the paranasal sinuses or the external auditory canal. Although multiple retrospective clinical studies of ACC have been reported to date, clinical questions, such as 1) long-term prognosis beyond 20 years, 2) usefulness and suitability for treatment of therapeutic interventions, 3) therapeutic goal to aim for, and 4) prognosis by recurrence sites, are still unclear. METHODS: To improve understanding and management of adenoid cystic carcinoma of the head and neck (ACC), a retrospective study with 58 new ACC cases between 1991 and 2016 was performed. The median observation period was 66.8 months (range 3-316 months). The overall clinical stages were as follows: I, 6.9%; II, 25.9%; III, 19.0%; and IV, 48.2%. Histology was cribriform/tubular type (C-T type) in 62.0% and solid type in 27.5%. The main treatment strategy was definitive surgery, which was performed in 75.2% of cases. RESULTS: Overall 10-year, 20-year, and 25-year survivals were 63.7, 27.3, and 20.0%, respectively. Similarly, disease-specific survival (DSSs) was 65.7, 51.2, and 38.4%, respectively, and disease-free survival was 25.2, 9.4, and 9.4%, respectively. Conducting surgery (HR: 0.19, 95% CI: 0.06-0.61, p = 0.005) and C-T type (HR: 0.32, 95% CI: 0.11-0.93, p = 0.036) were independent prognostic predictors of DSS. DSS was significantly prolonged after salvage surgery for both locoregional recurrence (p = 0.004) and lung metastatic recurrence (p = 0.012, vs best supportive care). CONCLUSIONS: In ACC cases, both initial surgical treatment and repetitive surgical resection of resectable recurrent lesions, including both locoregional and lung metastases, resulted in longer survival. The major goal of treatment for ACC may be long-term survival including cancer-bearing survival, resulting in either natural death or intercurrent-disease death, since judging cure of ACC is almost impossible. TRIAL REGISTRATION: Retrospectively registered.

[Management of emergency vs. otorhinolaryngology department tracheobronchial foreign-body aspiration].

Foreign-body aspiration (FBA) obstructing the airways may lead to choking and cardiopulmonary arrest without immediate emergency care. We retrospectively reviewed medical records of 17 otorhinolaryngology subjects-8 men and 9 women aged 0 to 84 years-88% of whom were < 3 years old, requiring tracheobronchial FBA between January 1995 and October 2006 and of 62 emergency subjects-43 men and 19 women aged 0 to 91 years--10% of whom were < 3 yeares old 68% of whom > or = 50 years old, admitted between January 2000 and October 2006. Emergency Department personnel saw a mean of 8.9 patients per year versus the mean of 1.4 patients per year seen by Otorhinolaryngology Department personnel. Foreign bodies extracted most frequently from the 17 otorhinolaryngology patients were 9 seen for peanut injestion followed by 1 each seen for bean, screw, and false teeth injestion among other objects. Sixteen of the 17 were discharged without complications. Foreign bodies extracted from the 62 emergency patients most frequently involved food, especially rice cakes. Over half seen had already gone into cardiopulmonary arrest upon arrival and required cardiopulmonary resuscitation. Of the 62, 32 patients died, 13 were sent to another hospital after in-patient care, 9 were sent home without admission, and 7 were discharged without complications.

Nonrecurrent inferior laryngeal nerve without vascular anomaly as a genuine entity.

Inferior laryngeal nerve (ILN), which usually arises from vagus nerve, runs recurrent course and is called recurrent ILN (RILN). Intimate knowledge of normal and anatomic variants of the ILN reduces the risk of nerve injury and vocal cord paralysis in thyroid and parathyroid surgery. The nonrecurrent ILN (NRILN) is a rare nerve anomaly that is associated with a right aberrant subclavian artery. We encountered 2 patients with NRILN during thyroid surgery. Patient 1, a 57-year-old woman, had mediastinal thyroid tumor without vascular anomaly. Patient 2, a 47-year-old woman with a history of esophageal foreign body (fish bone), was suspected to have NRILN with vascular anomaly before surgery, as judged by preoperative enhanced CT. In the patient 1, we verified laryngeal mobility function of the NRILN by nerve stimulation, and confirmed the absence of RILN in usual recurrent course. The findings in the patient 1 indicate that NRILN without subclavian artery anomaly is a genuine entity. In both patients we performed thyroid surgery safely and fast by expectation and identification of NRILN by use of nerve stimulator. In conclusion, we confirm the existence of NRILN without vascular anomaly and show effectiveness of preoperative enhanced CT and valuable use of nerve stimulator for nerve preservation in the patients with NRILN.

Predictors of chewing and swallowing disorders after surgery for locally advanced oral cancer with free flap reconstruction: A prospective, observational study.

OBJECTIVE: Surgery for locally advanced oral cancer often requires wide resections of multiple subsites of the oral cavity, including the oral tongue, floor of the mouth, and lower gingiva, and it causes chewing and swallowing disorders. The aim of this prospective, observational study was to determine which subsites have a greater impact on chewing and swallowing disorders after surgery. METHODS: A prospective, observational study was conducted involving 52 patients who underwent surgery for locally advanced oral cancer with free flap reconstruction. The patients' Functional Oral Intake Scale scores were measured before surgery and 1 and 3 months after surgery. Possible predictors of chewing and swallowing disorders were subjected to univariate analysis and multivariate logistic regression analysis. Age, sex, preoperative body mass index, clinical stage, extent of mandibular bone resection, floor of the mouth resection, total or subtotal glossectomy, laryngeal suspension, bilateral neck dissection, and postoperative radiation therapy were the variables evaluated. RESULTS: Multivariate logistic regression analysis showed that both anterior or extensive mandibular bone resection and postoperative radiation therapy were independently associated with poor oral intake after surgery. CONCLUSIONS: The identified predictors will be helpful for better management of patients identified as being at high risk of chewing and swallowing disorders.

[A clinical study of 71 cases of acute epiglottitis].

Acute epiglottitis causes sudden upper airway obstruction that may become lethal, and must be diagnosed and treated quickly and precisely. We review clinical features of 71-cases of acute epiglottitis in 6 years, focusing in cases requiring emergency airway management. Retrospective analysis was done for 1) age and gender, 2) month of onset, 3) symptoms, 4) smoking history, 5) diabetes history, 6) cause and background, 7) first medical institution visit, 8) duration from symptom onset to hospital visit, 9) oropharyngeal findings, 10) laryngendoscopic findings, 11) pharyngeal culture, and 12) deterioration after hospitalization. We found that 2 cases deteriorated in laryngendoscopic findings after hospitalization despite treatment. Even if the first medical findings are mild, it is necessary to respond to patients with the possibility to deterioration in mind. Five cases required emergency airway management-3 with tracheostomy and 2 cases with endotracheal intubation. If symptoms of laryngeal edema, oxygen desaturation, and dyspnea are present, emergency airway management should be prepared soon after hospitalization.

PD-1 Expression in Head and Neck Squamous Cell Carcinomas Derives Primarily from Functionally Anergic CD4+ TILs in the Presence of PD-L1+ TAMs.

Oral tongue squamous cell carcinoma (OTSCC) is the most common oral cavity tumor. In this study, we examined the basis for the activity of programmed cell death protein (PD-1)-based immune checkpoint therapy that is being explored widely in head and neck cancers. Using multispectral imaging, we systematically investigated the OTSCC tumor microenvironment (TME) by evaluating the frequency of PD-1 expression in CD8+, CD4+, and FoxP3+ tumor-infiltrating lymphocytes (TIL). We also defined the cellular sources of PD-1 ligand (PD-L1) to evaluate the utility of PD-1:PD-L1 blocking antibody therapy in this patient population. PD-L1 was expressed in 79% of the OTSCC specimens examined within the TME. Expression of PD-L1 was associated with moderate to high levels of CD4+ and CD8+ TILs. We found that CD4+ TILs were present in equal or greater frequencies than CD8+ TILs in 94% of OTSCC and that CD4+FOXP3neg TILs were colocalized with PD-1/PD-L1/CD68 more frequently than CD8+ TILs. Both CD4+PD1+ and CD8+PD1+ TILs were anergic in the setting of PD-L1 expression. Overall, our results highlight the importance of CD4+ TILs as pivotal regulators of PD-L1 levels and in determining the responsiveness of OTSCC to PD1-based immune checkpoint therapy. Cancer Res; 77(22); 6365-74. ©2017 AACR.

Bioactivity and mechanical properties of cellulose/carbonate hydroxyapatite composites prepared in situ through mechanochemical reaction.

Organic-inorganic composites, prepared from bone-bonding bioactive ceramics and organic polymers, are useful for novel bone substitutes having mechanical properties analogous to natural bone. We synthesized composites from cellulose and carbonate hydroxyapatite (CHAp) in situ through mechanochemical reaction. They contained B-type CHAp analogous to bone apatite. They showed a bending strengths of 10-13 MPa and Young's modulus of 1.5-2.2 GPa. We predicted their microstructure by comparing the measured density with the theoretical one. Cellulose was assumed to be distributed in the pore of CHAp at low cellulose content, and in grain boundaries of CHAp at high cellulose content. The composites formed calcium phosphate on their surfaces in simulated body fluid, meaning that they have a potential to be bioactive.

Apatite mineralization behavior on polyglutamic acid hydrogels in aqueous condition: effects of molecular weight.

Apatite-polymer composites mimicking specific structure of natural bone are promised as bone substitutes with moderate flexibility able to be fabricated into desired shapes as well as bone-bonding bioactivity. In order to precipitate the apatite on polymer surfaces, aqueous processing using solution supersaturated to the apatite has been attracting as much attention. Polyglutamic acid (PGA) is a promised candidate of the polymer, since it has high apatite-forming ability owing to abundant carboxyl groups able to trigger the heterogeneous apatite nucleation. Although combination of PGA with different molecular weight is expected to provide design of organic-inorganic composites with moderate bioresorbability, precise relationship between the molecular weight of the PGA and its apatite-forming ability has been remained unclear. In the present study, PGA hydrogels with different molecular weight were prepared by covalent cross-linking using ethylenediamine. Difference in apatite formation in simulated body fluid (SBF) was interpreted in terms of their chemical structure. It was found that hydrogels prepared from PGA with higher molecular weight showed tendency to have higher apatite-forming ability. It was attributed to high content of the carboxyl group remaining on the hydrogel due to low degree of the cross-linking.