Spectral and spatial resolving of photoelectric property of femtosecond laser drilled holes of GaSb(1-x)Bi(x).

Femtosecond laser drilled holes of GaSbBi were characterized by the joint measurements of photoconductivity (PC) spectroscopy and laser-beam-induced current (LBIC) mapping. The excitation light in PC was focused down to 60 µm presenting the spectral information of local electronic property of individual holes. A redshift of energy band edge of about 6-8 meV was observed by the PC measurement when the excitation light irradiated on the laser drilled holes. The spatial resolving of photoelectric property was achieved by the LBIC mapping which shows "pseudo-holes" with much larger dimensions than the geometric sizes of the holes. The reduced LBIC current with the pseudo-holes is associated with the redshift effect indicating that the electronic property of the rim areas of the holes is modified by the femtosecond laser drilling.

[Evaluation of the effect of free fibular flap transplantation in repairing mandibular osteoradionecrosis defect in 151 cases].

Objective: To investigate the clinical effect of free fibula flap transplantation in repairing the defect of mandibular osteoradionecrosis (ORN). Methods: A total of 151 mandibular ORN patients undergoing free fibular flap transplantation were selected from August 2005 to September 2020 in the Department of Oral and Maxillofacial Surgery, Sun Yat-sen Memorial Hospital, Sun Yat-sen University. Among them, 109 patients were males and 42 patients were females, aged (54.1±10.1) (ranged 31-85) years old. The clinical data of the patients was collected and the survival rate of the flaps and postoperative function were calculated to evaluate the surgical efficacy. The χ2 test was used for difference analysis. Results: Among the 151 patients, mandibular ORN caused by radiotherapy for nasopharyngeal carcinoma accounted for 79.5% (120/151). The average time for mandibular ORN appeared was 5(6) years after radiotherapy. Facial artery [57.2%(87/152)] and superior thyroid artery [32.9%(50/152)] were the main anastomotic arteries in the recipient area. There was no significant difference in the necrosis rates of the two flaps [10.3%(9/87) and 12.5% (5/50), respectively, P=0.949]. The main anastomotic veins in the recipient area were the external jugular vein [48.4%(135/279)] and the common facial vein [26.5%(74/279)]. Twenty-five cases (16.6%) had one vein anastomosed, and 126 cases (83.44%) had two veins anastomosed. There was no significant difference in the flap necrosis rate between the two conditions [20.0%(5/25) and 7.1%(9/126), respectively, P=0.100]. Ninety-seven cases (64.2%) used the peroneal musculocutaneous-fascia composite flap to repair the maxillofacial soft and hard tissue defects. Thirteen cases (8.6%) underwent the restorations with digital virtual surgery design, of which 5 cases were repaired with dental implants at the same time. After the operations, lower respiratory tract infection occurred in 17 patients (11.3%), and upper respiratory tract obstruction occurred in 3 cases (2.0%). The survival rate of the flap after operation was 90.7% (136/151), and 21 patients (13.9%) had flap vascular crisis. Delayed healing of maxillofacial wounds occurred in 33 cases (21.9%). After 3 to 24 months of follow-ups, 110 patients (76.9%) had no fistula inside/outside the oral cavity, 118 patients (82.5%) had an improvement in opening mouth of increasing (≥0.5 cm) after surgery, 135 patients (94.4%) had pain relief, 97 cases (67.8%) could eat normal diet, semi-liquid or soft food, and 137 cases (95.8%) were satisfied or basically satisfied with the treatment effects. Conclusions: The free fibular flap transplantation is an effective method to repair mandibular ORN defects. Preoperative vascular assessment is helpful for the selection of recipient vessels. Facial artery, superior thyroid artery, external jugular vein and common facial vein can be used as the main recipient vessels. The repair of the peroneal musculocutaneous-fascia composite flap facilitates the closure of internal and external fistulas. Digital technology can help to restore the maxillofacial shape more accurately, improve the patient's occlusal and chewing function and enhance the quality of life of mandibular ORN patients.

Outcomes of younger and older patients with palatal cancer undergoing pedicled facial-submental artery island flap reconstruction.

The purpose of this study was to evaluate the outcomes of younger and older patients with palatal cancer undergoing reconstruction using the pedicled facial-submental artery island flap (FSAIF) following cancer ablation. Fifty-eight patients with palatal squamous cell carcinoma (SCC) were divided into two age groups: ≤60 years (n=31) and >60 years (n=27). By clinical SCC stage, 6.4%, 83.9%, and 9.7% of the younger group and 3.7%, 85.2%, and 11.1% of the older group were stage I, II, and III, respectively. The incidence of comorbid conditions was 35.5% (11/31) in those ≤60 years and 137.0% (37/27) in those >60 years. Brown class II maxillary defects (four class IIa, 44 class IIb, three class IIc, and seven class IId) were repaired using FSAIFs following cancer ablation. There were two flap failures; thus the success rate was 96.6%. Significant differences in mean age and the incidence of comorbid conditions were evident between the groups. No significant differences in TNM stage, maxillary defect classification, flap size, overall flap survival, rates of local and general complications, or survival status was evident between the groups. The FSAIF is a reliable and safe method for repairing Brown class II maxillary defects following cancer ablation, particularly in older patients.

T cell epitope selection: dominance may be determined by both affinity for major histocompatibility complex and stoichiometry of epitope.

The majority of T cell hybridomas produced in the BALB/c mouse in response to immunization with lambda repressor cI recognize a peptide fragment comprising of residues 12 to 26 (P12-26). Some other parts of the cI (P1-14, P33-48 and P73-88) are defective in generating T cell responses in the BALB/c mouse. P73-88 may be converted into a T cell determinant if a few more amino acid residues are included (P67-88). Together with P46-67 and P80-102, most peptides derived from cI were capable of eliciting T cell responses by themselves in BALB/c mouse. The mechanisms underlying the selection of P12-26 over the other epitopes when lambda repressor was used as immunogen were examined. The dominant response to P12-26 was attenuated by tolerizing with intravenous administration of P12-26. Under such treatment the T cell response to P12-26 was reduced by 80% but there was no enhancement on the responses toward other epitopes. The selection of P12-26 is, thus, unlikely to be due to a competition at the T cell level. It was also found that the dominance of P12-26 was not simply due to a higher affinity of P12-26 for major histocompatibility complex molecules. For example P12-26 binds better to I-Ad molecule than P80-102, but co-injection with equimole of P12-26 only slightly inhibited P80-102-induced T cell response. Instead, it required a few molar excess of P12-26 to effectively block the association of P80-102 with I-Ad molecules and to inhibit the T cell immunity to P80-102. Since epitopes such as P46-67, P67-88 and P80-102 were generated from lambda repressor cI at a lower molar basis than that of P12-26, it is suggested that the dominance of P12-26 was probably generated by such stoichiometry difference, in addition to the higher affinity of P12-26 for I-Ad molecules.

Modulation of restricted class II T cell responses by peptides derived from self class II molecule.

We have explored the possibility of using peptides derived from a major histocompatibility complex (MHC) class II (I-Ab) molecule to modulate I-Ab-restricted T cell responses. Six peptides spanning the polymorphic regions of I-Ab were analyzed for competitive binding to the I-Ab molecule, and for efficacies in blocking I-Ab-specific T cell response. Only PB1 (residues 75-91 of beta chain) bound the I-Ab molecule with high affinity. When these MHC-derived peptides were administered simultaneously with antigen, PB1 effectively inhibited I-Ab-restricted T cell responses as well as another peptide PB2 (residues 59-78 of beta chain). PB2 inhibited specific T cell response only when it was administered simultaneously with antigen. Since PB2 is a weak binder of I-Ab, an additional mechanism must account for its inhibitory activity. Both PB1 and PB2 peptides elicited specific T cell responses, indicating that these peptides were not tolerogenic in syngeneic mice. However, the induction of T cells in response to PB1 and PB2 did not increase reactivity to I-Ab. MHC class II-derived peptides thus can be used to regulate T cell responses without the risk of autoreactivity.