Effects of intra-operative magnesium sulfate infusion on orthognathic surgery: A prospective and randomized controlled trial

Purpose

To comprehensively understand the effects of intra-operative infusion of magnesium sulfate on patients who underwent orthognathic surgery, including remifentanil consumption, postoperative pain, postoperative nausea and vomiting (PONV), inflammatory response, and serum magnesium levels.

Methods

Seventy-five adult patients undergoing orthognathic surgery under general balanced anesthesia were randomly divided into two groups. One group (Group M) received 50 mg/kg of magnesium sulfate in 20 mL 0.9 % saline after intubation, followed by a continuous infusion at a rate of 15 mg/kg/h until 30 min before the anticipated end of surgery. The other group (Group C) received an equal volume of isotonic saline as a placebo. (Clinical trial registration number: chiCTR2100045981).

Results

The primary outcome was remifentanil consumption. The secondary outcomes included the pain score assessed using the verbal numerical rating scale (VNRS) and PONV assessed using a Likert scale. Remifentanil comsumption in Group M was lower than Group C (mean ± SD: 0.146 ± 0.04 μg/kg/min vs. 0.173 ± 0.04 μg/kg/min, P = 0.003). At 2 h after surgery, patients in Group C suffered more severe PONV than those in Group M (median [interquartile range, IQR]: 1 [3] vs. 1 [0], mean rank: 31.45 vs. 42.71, P = 0.040). At post-anesthesia care unit (PACU), postoperative pain in Group C was severe than Group M (3 [1] vs. 3 [0], mean rank: 31.45 vs. 42.71, P = 0.013). Changes in haemodynamics and surgical field scores did not differ between the groups (all P > 0.05). The levels of cytokines (IL-4, IL-6, IL-8, IL-10, TNF-a, and MIP-1β) were not significantly different between the groups after surgery (all P > 0.05). Postoperative serum magnesium levels in Group C were lower than those in Group M (0.74 ± 0.07 mmol/L vs. 0.91 ± 0.08 mmol/L, P = 0.000) and the preoperative level (0.74 ± 0.07 mmol/L vs. 0.83 ± 0.06 mmol/L, P = 0.219).

Conclusions

In orthognathic surgery, magnesium sulfate administration can reduce remifentanil requirement and relieve PONV and postoperative pain in the early postoperative phase.

The relationship between eye canting and vertical craniofacial skeletal asymmetry in adult patients with dento-maxillofacial deformities

BACKGROUND

Whether eye canting in patients with asymmetric dento-maxillofacial deformities is the result of anatomical asymmetry or a compensatory head position remains controversial.

OBJECTIVE

This cross-sectional study aims to verify whether eye canting is correlated with craniofacial skeletal asymmetry.

METHODS & MATERIALS

This study was performed by measuring the computed tomographic scans of 223 patients with dento-maxillofacial deformities in Mimics 21.0 software. First grouping was determined based on the intersection angle between the line passing through bilateral lateral canthus point and Frankfurt horizontal plane, and final grouping was based on measurements of the pregroups.

RESULTS

The patients were finally categorized into three groups: symmetry group (n = 163), asymmetry subgroups 1 (n = 33) and asymmetry subgroups 2 (n = 27). The results of multiple linear regression and comparisons among groups suggests the presence of orbital skeletal asymmetry in patients with eye canting and the eye canting is partly increment dependent of orbital skeletal asymmetry when using bilateral ears as the reference. The result also reveals that there is a greater angle between the line through bilateral ocular landmarks and the line through the bilateral ear landmarks in patients with ocular canting compared to patient without eye canting.

CONCLUSION

Patients with asymmetric dento-maxillofacial deformities and with eye canting have vertical asymmetry of the orbital and cranial skeletal landmarks. These symmetry differences between the eyes and ears may affect the overall craniofacial symmetry after orthognathic surgery.

Controlled and Sequential Delivery of Stromal Derived Factor-1 α (SDF-1α) and Magnesium Ions from Bifunctional Hydrogel for Bone Regeneration

Bone healing is a complex process that requires the participation of cells and bioactive factors. Stromal derived factor-1 α (SDF-1α) and magnesium ions (Mg²⁺) both are significant bioactive factors for cell recruitment and osteogenesis during bone regeneration. Thus, a bifunctional hydrogel containing a sequential delivery system is fabricated to improve osteogenesis. During sequential delivery of the hydrogel, SDF-1α is predominantly released at the early stage of bone mesenchymal stem cells (BMSCs) recruitment, while Mg²⁺ are constantly delivered at a later stage to improve osteogenic differentiation of recruited cells. In addition, due to the early release of SDF-1α, the hydrogel showed strong BMSCs recruitment and proliferation activity. Mg²⁺ can not only induce up-regulation of osteogenic gene expression in vitro, but also promote bone tissue and angiogenesis in vivo. Taken together, the injection of xanthan gum-polydopamine crosslinked hydrogel co-loading SDF-1α and Mg²⁺ (XPMS hydrogel) provides a novel strategy to repair bone defects.

Experts' consensus on precaution and treatment for complications of sagittal split ramus osteotomy

Sagittal split ramus osteotomy (SSRO) is a versatile orthognathic procedure for correcting mandibular deformities. Various complications can possibly occur when performing SSRO, and it can even cause serious adverse consequences because of the complexity of anatomy and operative procedures. The types of complications and their accompanying clinical manifestations are closely related to the choice of diagnosis and treatment strategies and clinical outcomes. To discuss the causes, prevention, and treatment measures of various common complications of SSRO, domestic orthognathic surgery experts prepared this consensus to increase the awareness of SSRO complications, thereby ensuring safe surgical procedure and good results.

MMP25 Regulates Immune Infiltration Level and Survival Outcome in Head and Neck Cancer Patients

Background: MMP25 is a critical gene of matrix metalloproteinases (MMPs). However, the molecular mechanism of MMP25 in head and neck cancer pathogenesis remains unclear.

Methods: MMP25 expression was analyzed using The Cancer Genome Atlas (TCGA) database, and its influence on clinical prognosis was performed using Kaplan–Meier and Cox regression analyses. The correlation between MMP25 and immune infiltration was investigated by CIBERSORT, TIMER, and ESTIMATE. In addition, the relationship between MMP25 expression and molecular mechanisms was analyzed by gene set enrichment analysis (GSEA), gene ontology (GO), and weighted gene co-expression network analysis (WGCNA).

Results: MMP25 expression level correlated with prognosis and immune infiltrating levels, especially activated CD4⁺ memory T cells, in head and neck cancer. Moreover, MMP25 expression potentially mediated genes, such as IRF8, IKZF1, and DOCK2, and tumor-associated pathways, including p53 signaling, PI3K/AKT/mTOR signaling, and JAK/STAT signaling pathway.

Conclusions: These findings suggested that MMP25 plays a critical role in the prognosis and immune infiltration level of head and neck cancer. In addition, MMP25 expression significantly correlated with the regulation of various oncogenes and tumor-related pathways.

CA9 transcriptional expression determines prognosis and tumour grade in tongue squamous cell carcinoma patients

CA9 is a member of the carbonic anhydrases’ family, that is often expressed in cancer cells under hypoxic condition. However, the role of CA9 in the molecular mechanisms of tongue squamous cell carcinoma (TSCC) pathogenesis remains unclear. CA9 expression was analysed using the TCGA database, and its influence on survival was performed using Kaplan‐Meier, LASSO and COX regression analyses. The correlation between CA9 and immune infiltration was investigated by CIBERSORT and ESTIMATE. Moreover, the relationship between CA9 expression and downstream molecular regulation pathways was analysed by GSEA, GO and WGCNA. CA9 expression correlated with clinical prognosis and tumour grade in TSCC. Moreover, CA9 expression potentially contributes to the regulation of cancer cell differentiation and mediates tumour‐associated genes and signalling pathways, including apoptosis, hypoxia, G2M checkpoint, PI3K/AKR/mTOR signalling and TGF‐beta signalling pathways. However, the follicular helper T cells, regulatory T cells, immune and stromal scores showed no significance between high and low CA9 expression groups. These findings suggested that CA9 plays a critical role of TSCC prognosis and tumour grade. CA9 expression significantly correlated with the regulation of cell differentiation, various oncogenes and cancer‐associated pathways.

Application of Electrospinning Strategy on Cartilage Tissue Engineering

Cartilage, constituted with a relatively hypocellular structure and lacking of neural and vascular connections, is not a well self-repairing tissue. Cartilage tissue engineering involving bulk of biomaterials has been put forward as a strategy for articular cartilage lesions. The most complicated issue for cartilage repairing is to simulate the highly hierarchical structure, extracellular matrix (ECM) composition and even mechanical features. Electrospinning can produce flexible, dense fibrous membranes with moderate mechanical properties and biological features with different constitution of polymer, orientation, diameter and morphology of fibers, or cooperation forms with other strategies. In our review, four classes are mentioned for cartilage tissue engineering and kinds of biomaterials to be utilized.

Inhibition of osteogenesis surrounding the titanium implant by CGRP deficiency

Previous studies have suggested one of the neurotransmitters, calcitonin gene-related peptide (CGRP), modulates local regulation of bone metabolism; however, the regulating signaling pathway is still being explored. The objective of this study was to determine whether CGRP deficiency affects the osteogenesis surrounding titanium implants in vivo. Titanium screws were implanted in 72 adult rats, which were divided into three groups randomly: Sham, inferior alveolar neurectomy (IAN), and IAN+CGRP. Saline solution containing CGRP (concentration: 100 nmol/L) was injected into the area surrounding the implants in the IAN+CGRP group every day post operation. According to histological observations and Micro-CT, osteogenesis surrounding the implant was suppressed in the IAN group compared to that in the Sham and IAN+CGRP groups; the highest degree of osteogenesis was observed in the Sham group. This effect was also proved via the gene expressions of osteocalcin and runt-related transcription factor 2 surrounding the implant by real-time (RT) PCR analysis. In addition, through immunofluorescence staining and RT-PCR analysis, levels of CGRP and β-catenin were also reduced in the IAN group, while the highest expression was observed in the Sham group (p < 0.05). Our results collectively suggest that the titanium implant bone model established by IAN exhibited CGRP deficiency and reduced osteogenesis surrounding the implant. Additionally, the expression analyses suggest that the canonical Wnt signaling pathway could be involved in this process of bone metabolism in vivo.

Zoledronate suppressed angiogenesis and osteogenesis by inhibiting osteoclasts formation and secretion of PDGF-BB

PURPOSE

Bisphosphonates related osteonecrosis of jaw (BRONJ) is a severe complication of systemic BPs administration, the mechanism of which is still unclarified. Recently, platelet-derived growth factor-BB (PDGF-BB) secreted by preosteoclasts was reported to promote angiogenesis and osteogenesis. This study aimed to clarify whether bisphosphonates suppressed preosteoclasts releasing PDGF-BB, and whether the suppression harmed coupling of angiogenesis and osteogenesis, which could contribute to BRONJ manifestation.

METHODS AND RESULTS

Zoledronate significantly inhibited osteoclast formation by tartrate-resistant acid phosphatase (TRAP) staining and PDGF-BB secretion tested by ELISA. In line with decreasing secretion of PDGF-BB by preosteoclasts exposed to zoledronate, conditioned medium (CM) from the cells significantly induced less migration of endothelial progenitor cells (EPCs) and mesenchymal stem cells (MSCs) compared to CM from unexposed preosteoclasts. Meanwhile, angiogenic function of EPCs and osteoblastic differentiation of MSCs also declined when culturing with CM from preosteoclasts treated by zoledronate (PZ-CM), evidenced by tube formation assay of EPCs and alkaline phosphatase activity of MSCs. Western blot assay showed that the expression of VEGF in EPCs and OCN, RUNX2 in MSCs declined when culturing with PZ-CM compared to CM from preostoeclasts without exposure of zoledronate.

CONCLUSION

Our study found that zoledronate was able to suppress preosteoclasts releasing PDGF-BB, resulting in suppression of angiogenesis and osteogenesis. Our study may partly contributed to the mechanism of BRONJ.

Risk factors and prognosis for salivary gland adenoid cystic carcinoma in southern china: A 25-year retrospective study

Adenoid cystic carcinoma (ACC) is characterized by slow growth, frequent local recurrences, and high incidence of distant metastasis (DM). The aim of this study was to evaluate predictive factors for local-regional (LR) recurrence, DM, and survival in ACC.A retrospective review of the medical records for patients with salivary glands ACC from 1990 to 2015 was performed. The clinical parameters were assessed to identify correlations with the development of LR recurrence, DM, and survival of these patients.Among 228 patients who underwent surgery as definitive treatment, 210 (92.1%) were followed up in the study. DM was detected in 64 (30.5%) patients, LR recurrence was detected in 58 (27.6%) patients. The estimated 5, 10, and 15-year overall survival rates were 84.7%, 70.8%, and 34.0%, respectively. Multivariate analysis revealed that the presence of lymphovascular invasion and a high T classification were very strong adverse factors, which independently influenced LR recurrence, DM, and survival of ACC patients. Positive/close margin and N+ status were independent risk factors for DM and LR recurrence, respectively. Survival of ACC patents was also affected by tumor location.Presence of lymphovascular invasion and a high T classification were very strong adverse factors and independent predictors for ACC patients' prognosis, which influenced LR control, DM control, and survival.

Current concepts in odontohypophosphatasia form of hypophosphatasia and report of two cases

BACKGROUND

Hypophosphatasia is a rare inherited disease derived from mutations in tissue non-specific alkaline phosphatase genes, with typical oral symptoms including short root anomaly and dysplasia of dentin or cementum.

CASE PRESENTATION

Two young female patients presented with short root anomaly with a history of premature loss of deciduous and/or permanent teeth. The laboratory and imaging investigations were performed. One case was diagnosed as odontohypophosphatasia concurrent with hyperthyroidism, the other was odontohypophosphatasia concurrent with multiple radicular cysts.

CONCLUSION

This report presents two cases of odontohypophosphatasia, a rare disease which is difficult to be diagnosed, and highlights that the history of premature loss of deciduous and/or permanent teeth, oral manifestation and laboratory tests are crucial for clinical diagnosis.

Reconstruction of Tongue Defects With the Contralateral Nasolabial Island Flap

PURPOSE

Reconstruction of tongue defects after cancer resection is challenging for reconstructive surgeons. Conventional local flaps are usually compromised in patients with suspected ipsilateral neck metastasis. To extend the application of the nasolabial flap, especially in circumstances in which a free flap is unavailable, the contralateral nasolabial island flap was used, with favorable outcomes.

PATIENTS AND METHODS

Seven patients presenting with tongue carcinoma underwent surgical resection and neck dissection. Tongue defects were simultaneously reconstructed using a contralateral nasolabial island flap. Clinical outcomes, including locoregional recurrence and distant metastasis, were recorded. Subjective functional outcomes were investigated using the University of Washington Quality of Life Questionnaire.

RESULTS

All flaps survived without partial or complete necrosis. All patients survived without locoregional recurrence or distant metastasis during follow-up (6 months to 2 years). Functional outcomes were satisfactory, especially swallowing and speech functions. Donor-site morbidity was minimal and the scars were inconspicuously hidden in the nasolabial fold.

CONCLUSIONS

The contralateral nasolabial island flap is technically feasible and can be an excellent option for tongue reconstruction without compromising oncologic safety.

Differential expression proteins associated with bud dormancy release during chilling treatment of tree peony (Paeonia suffruticosa)

Endo-dormant flower buds of tree peony must have sufficient chilling duration to reinitiate growth, which is a major obstacle to the forcing culture of tree peony in winter. We used a combination of two-dimensional gel electrophoresis (2-DE) and matrix-assisted laser desorption/ionisation time of flight/time of flight mass spectrometry (MALDI-TOF/TOF MS) to identify the differentially expressed proteins of tree peony after three different chilling treatments: endo-dormancy, endo-dormancy release and eco-dormancy stages. More than 200 highly reproducible protein spots were detected, and 31 differentially expressed spots (P < 0.05) were selected for further analysis. Finally, 20 protein spots were confidently identified from databases, which were annotated and classified into seven functional categories: response to abiotic or biotic stimulus (four), metabolic processes (four), other binding (three), transcription or transcription regulation (two), biological processes (one), cell biogenesis (one) and unclassified (five). The results of qPCR of five genes were mainly consistent with that of the protein accumulation analysis as determined by 2-DE. This indicated that most of these genes were mainly regulated at transcriptional level. The activity of nitrate reductase and pyruvate dehydrogenase E1 was consistent with the 2-DE results. The proteomic profiles indicated activation of citrate cycle, amino acid metabolism, lipid metabolism, energy production, calcium signalling and cell growth processes by chilling fulfilment to facilitate dormancy release in tree peony. Analysis of functions of identified proteins will increase our knowledge of endo-dormancy release in tree peony.

Inhibition of autophagy enhances cisplatin cytotoxicity in human adenoid cystic carcinoma cells of salivary glands

BACKGROUND

The relationship between autophagy and chemotherapy in cancer has been studied a lot recent years. However, there is currently no study on the role of autophagy in chemotherapy of adenoid cystic carcinoma (ACC) of human salivary glands. We hypothesized that autophagy plays a protective role for human salivary gland ACC cells during chemotherapy, diminishes the effect of treatment, and ultimately results in poor sensitivity to chemotherapy.

MATERIALS AND METHODS

After inhibition of autophagy by 5 mM 3-methyladenine (3MA), 20 μM Chloroquine (CQ), or Beclin-1 shRNA, we examined the sensitivity of human salivary gland ACC cells to different concentrations of cis-diamminedichloroplatinum (CDDP) using MTT assay. Also, levels of autophagy in ACC cells treated by CDDP were assessed by western blot, GFP-LC3 fluorescence and transmission electron microscopy (TEM).

RESULTS

Inhibition of autophagy induced by 3MA, CQ, or Beclin-1 shRNA could all enhance human salivary gland ACC cell death treated by CDDP. And, levels of autophagy in these cells showed a significant increase after treated by CDDP.

CONCLUSION

Autophagy played a protective role for human salivary gland ACC cells during CDDP chemotherapy. Inhibition of autophagy in these cells could enhance cisplatin cytotoxicity-effects. These findings indicate a novel and promising way to reduce chemotherapy resistance and improve treatment outcome in human salivary gland ACC.

Mandible reconstruction assisted by preoperative virtual surgical simulation

OBJECTIVE

In this study, we evaluated the clinical efficacy of mandible reconstruction with preoperative virtual planning, which focused on esthetics and occlusion.

STUDY DESIGN

A series of 9 patients were enrolled prospectively to undergo mandibulectomy and simultaneous reconstruction. Preoperative spiral CT scans of the maxillofacial region and the fibula region were performed. Virtual surgery of tumor resection and fibula reconstruction was performed in the Mimics platform. The reconstructed mandible models were fabricated with CAD/CAM technique. The reconstruction plate and the positioning template were accommodated to the stereolithographic model as the surgical template.

RESULTS

Surgery was performed accurately according to the templates. All the fibula flaps survived. The appearance and occlusion of the patients were satisfactory.

CONCLUSIONS

With preoperative virtual planning, the spatial relationship of the mandible and the fibula graft can be planned individually, which helps achieve optimum appearance and occlusion relationship.

Sialoendoscopic secondary intervention after failure of open sialolithectomy

PURPOSE

Traditionally, sialoadenectomy was always indicated when open sialolithectomy failed. The aim of the present study was to investigate the role of sialoendoscopy as the secondary intervention after failure of open sialolithectomy.

PATIENTS AND METHODS

A consecutive series of 15 patients with obstructive salivary gland disease with failure of open sialolithectomy were prospectively recruited for our study. All these patients underwent sialoendoscopy under local anesthesia. The reasons for the failure of open sialolithectomy were analyzed, and secondary interventions were performed using sialoendoscopy.

RESULTS

Failure of open sialolithectomy resulted from 4 main causes. Small stones could not be found after the duct was incised (n = 3); the stones were pushed posteriorly during open surgery (n = 4); the stones located in the anterior part of the duct were removed, but the hilar stones were left untouched (n = 5); and radiolucent stones were missed (n = 3). All the patients were treated successfully by sialoendoscopy. No symptoms or signs of recurrence developed during a median follow-up period of 16 months.

CONCLUSIONS

Sialoendoscopy can be recommended as an effective secondary intervention after failure of open sialolithectomy.

Sialoendoscopically assisted open sialolithectomy for removal of large submandibular hilar calculi

PURPOSE

The management of large hilar calculi is a technically challenging issue during sialoendoscopic surgery. The aim of the present study was to evaluate the clinical efficacy of sialoendoscopically assisted open sialolithectomy for the removal of large submandibular hilar calculi to avoid sialoadenectomy.

PATIENTS AND METHODS

The present study was undertaken among patients with sialolithiasis scheduled for sialoendoscopic surgery from August 2005 to October 2008. When we failed to remove large submandibular hilar stones intraductally, we performed sialoendoscopically assisted open sialolithectomy. The clinical characteristics, pre- and intraoperative data, and outcomes were documented in a prospective fashion.

RESULTS

Of 78 consecutive patients with submandibular sialolithiasis, 18 were treated with sialoendoscopically assisted open sialolithectomy immediately after failure of intraductal removal of calculi by sialoendoscopy. For 17 patients, large hilar sialoliths were successfully removed using this surgical technique. The surgery failed in 1 patient with multiple sialoliths, and the procedure was converted to open sialoadenectomy. Temporary numbness of the tongue for 1 week postoperatively was documented in 3 patients. The patients were followed up for a median period of 18 months without any symptoms or signs of recurrence.

CONCLUSION

Our results suggest that sialoendoscopically assisted open sialolithectomy is an effective and safe surgical technique to remove large submandibular hilar calculi.

CT virtual sialendoscopy versus conventional sialendoscopy in the visualization of salivary ductal lumen: an in vitro study

OBJECTIVES/HYPOTHESIS

To evaluate the feasibility of computed tomographic (CT) virtual sialendoscopy and its performance characteristics for the visualization of salivary ductal lumen as compared with conventional sialendoscopy.

STUDY DESIGN

An in vitro study.

METHODS

Conventional sialendoscopy was performed in 16 submandibular glands in vitro and the surgical findings were recorded. Then a contrast agent was injected into the Wharton's duct via orifice. After CT scanning, the CT data were transferred to an independent workstation and were postprocessed with commercially available software to generate three-dimensional reconstructive and virtual sialendoscopic images. Finally, the plastination of submandibular glands was performed with 20% perchloroethylene ethyl acetate plastics filler to make cast specimens. CT three-dimensional reconstruction of the ductal system was compared with the cast specimen, and the performance of conventional sialendoscopy and CT virtual sialendoscopy for the visualization of salivary ductal lumen was also compared.

RESULTS

The CT data acquisition and postprocessing protocol were feasible. CT three-dimensional reconstruction enabled clear visualization of the ductal system from any directions and angles, which showed close resemblance to the cast specimens. And CT virtual sialendoscopy created clear endoluminal views of salivary ducts simulating those obtained with conventional sialendoscopy.

CONCLUSIONS

Our initial experience shows that CT virtual sialendoscopy has the potential to be an attractive imaging technique for the visualization of salivary ductal lumen.

Neoadjuvant chemotherapy of cisplatin and fluorouracil regimen in head and neck squamous cell carcinoma: a meta-analysis

BACKGROUND

The benefit of neoadjuvant chemotherapy in the management of head and neck squamous cell carcinomas (HNSCC) still remains controversial. The aim of this meta-analysis is to evaluate the role of the neoadjuvant chemotherapy with the cisplatin and fluororacil (PF) regimen in enhancing the overall survival of and decreasing locoregional relapse and distant metastasis in HNSCC patients.

METHODS

Medline and manual searches were performed to identify all published randomized controlled trials (RCTs) investigating the efficacy of the neoadjuvant chemotherapy with the PF regimen. Outcomes assessed by meta-analysis included locoregional relapse, distant metastasis, and overall survival. The odds ratio was the principle measurement of effect, which was calculated as the treatment group (chemotherapy plus locoregional treatment) versus the control group (locoregional treatment alone) and was presented as a point estimate with 95% confidence intervals (CI).

RESULTS

Eight RCTs were adopted for analysis. The meta-analysis showed that the odds ratio for the locoregional relapse was 0.92 (0.70 - 1.22, 95% CI), which was not statistically significant. The odds ratios for distant metastasis and overall survival were 0.47 (0.33 - 0.68, 95% CI) and 1.28 (1.01 - 1.62, 95% CI) respectively, which were both statistically significant.

CONCLUSIONS

Neoadjuvant chemotherapy with the PF regimen in HNSCC patients has no effect on locoregional relapse. However, it shows a small but significant benefit in reducing distant metastasis and improving the overall survival.

Seroepidemiological and molecular evidence for the presence of two H3N8 equine influenza viruses in China in 1993-94

In May 1993, a severe epidemic of respiratory disease began in horses in Inner Mongolia and spread throughout horses in China. The disease affected mules and donkeys as well as horses but did not spread to other species, including humans. The severity of the disease raised the question of whether the outbreak might have been caused by the new avian-like influenza viruses detected in horses in China in 1989 or by current variants ofA/equine/Miami/1/63 (H3N8) (equine-2) or by a reassortant between these viruses. Antigenic and sequence analysis established that all gene segments of the influenza virus causing the epidemic were of recent equine-2 origin and that the virus was not a reassortant. Serological analysis of post-infection horse sera provided evidence for the continued circulation of the A/Equine/Jilin/1/89 (Eq/Jilin) (H3N8) avian-like viruses in horses in Heilongjiang province with original antigenic sin-like responses. It is noteworthy that prior infection with the avian-like Eq/Jilin strain did not afford cross-protection against a current equine-2 strain. Serological evidence for the continued circulation of the avian-like H3N8 influenza virus in horses indicates that this virus has probably established itself in horses in Asia.