Deep Underground Laboratory Measurement of

The ^{13}C(α,n)^{16}O reaction is the main neutron source for the slow-neutron-capture process in asymptotic giant branch stars and for the intermediate process. Direct measurements at astrophysical energies in above-ground laboratories are hindered by the extremely small cross sections and vast cosmic-ray-induced background. We performed the first consistent direct measurement in the range of E_{c.m.}=0.24 to 1.9 MeV using the accelerators at the China Jinping Underground Laboratory and Sichuan University. Our measurement covers almost the entire intermediate process Gamow window in which the large uncertainty of the previous experiments has been reduced from 60% down to 15%, eliminates the large systematic uncertainty in the extrapolation arising from the inconsistency of existing datasets, and provides a more reliable reaction rate for the studies of the slow-neutron-capture and intermediate processes along with the first direct determination of the alpha strength for the near-threshold state.

Orbital-Selective Kondo Entanglement and Antiferromagnetic Order in USb_{2}.

In heavy-fermion compounds, the dual character of f electrons underlies their rich and often exotic properties like fragile heavy quasiparticles, a variety of magnetic orders and unconventional superconductivity. 5f-electron actinide materials provide a rich setting to elucidate the larger and outstanding issue of the competition between magnetic order and Kondo entanglement and, more generally, the interplay among different channels of interactions in correlated electron systems. Here, by using angle-resolved photoemission spectroscopy, we present the detailed electronic structure of USb_{2} and observe two different kinds of nearly flat bands in the antiferromagnetic state of USb_{2}. Polarization-dependent measurements show that these electronic states are derived from 5f orbitals with different characters; in addition, further temperature-dependent measurements reveal that one of them is driven by the Kondo correlations between the 5f electrons and conduction electrons, while the other reflects the dominant role of the magnetic order. Our results on the low-energy electronic excitations of USb_{2} implicate orbital selectivity as an important new ingredient for the competition between Kondo correlations and magnetic order and, by extension, in the rich landscape of quantum phases for strongly correlated f electron systems.

[Clinical possibility of low ligation of inferior mesenteric artery and lymph nodes dissection in laparoscopic low anterior resection].

OBJECTIVE: To investigate the clinical possibility of low ligation of inferior mesenteric artery (IMA) and lymph nodes dissection in laparoscopic low anterior resection. METHODS: Data was collected retrospectively from 216 patients who underwent laparoscopic low anterior resection in our hospital from June 2011 to January 2015.Patients were divided into control group (132 cases) and observation group (84 cases). The observation group was treated with low ligation of IMA and lymph nodes dissection, and the control group was cured by high ligation of IMA and lymph nodes dissection. We analyzed the operation time, the number of lymph nodes dissection, the number of lymph nodes removed around the root of IMA, the rate of lymph node metastasis around the root of IMA, the incidence of anastomotic leakage and the ventilation time after the operation. RESULTS: There was no significant difference between the two group in the pre-operative data, operation time, the number of lymph nodes dissection the number of lymph nodes removed around the root of IMA, the rate of lymph node metastasis around the root of IMA and the incidence of anastomotic leakage (P>0.05). The observation group were significantly better than the control group the in the ventilation time after the operation (P<0.05). The follow up time was 12 to 67 months. The median follow up time was 37 months. One patient in observation group died of cardiovascular disease. One patient in control group died of metastatic carcinoma. CONCLUSION: Detection of low ligation of inferior mesenteric artery and lymph nodes dissection in laparoscopic low anterior resection is safe and practicable, which should be widely applied.

[Combination measurement of liver and spleen stiffness with portal vein width to evaluate risk of bleeding in esophageal and gastric varices patients].

OBJECTIVE: To evaluate the utility of combined liver stiffness measurement (LSM) and spleen stiffness measurement (SSM), by transient elastography, along with measurement of portal vein width (PVW) for evaluating risk of bleeding in patients with esophageal and gastric varices (EV). METHODS: A total of 73 patients with cirrhosis who were treated in the Department of Gastroenterology of the Second Affiliated Hospital of Xi'an Jiaotong University between April 2014 and March 2015 were included in the study. Child-Pugh classifications were obtained, portal vein widths were measured by ultrasound, liver and spleen stiffness were measured by transient elastography using FibroTouch®. Patients were examined by electronic endoscopy, upper abdominal computed tomography and standard serum testing. The serum indexes of fibrosis (aspartate aminotransferase (AST) to platelet ratio index (APRI), and AST to alanine aminotransferase ratio (AAR)) were calculated. Patients were grouped according to the results of gastroscopy, with severe (EV) and high risk of bleeding comprising group A and no or mild-to-moderate EV and low risk of bleeding comprising group B. Statistical analysis was carried out with t-test for continuous variables and χ(2) test for categorical variables to first screen out variables different between groups then the correlation with severe EV was assessed by generating receiver operating characteristic (ROC) curves. Lastly, binary logistic regression was used to evaluate the performance of combined variables for diagnosing severe EV and their predictive value for risk of bleeding. RESULTS: Group A and B showed significant differences for LSM, SSM and PVW (all P < 0.05). The cutoff values for diagnosing severe EV were 23.4 kPa for LSM, 40.3 kPa for SSM and 11.5 mm for PVW, with areas under the ROC curve (AUROC) as 0.655, 0.788 and 0.709 respectively. For combined measurements, the AUROC was 0.773 for LSM plus PVW and 0.840 for LSM plus PVW (with highest diagnostic performance). CONCLUSIONS: Combination of SSM plus PVW measurement shows high diagnostic performance for evaluating severe EV, and better performance than LSM plus SSM plus PVW and LSM plus PVW, with good predictive value for risk of EV bleeding.

[Clinical and anatomic study of preserving parathyroid specific adipose attachments in total thyroidectomy].

Objective: To discuss the anatomical characteristic and important role of specific adipose attachments in preserving parathyroid function in total thyroidectomy. Methods: Parathyroid glands of 91 cases underwent total thyroidectomy in Department of General Surgery, Beijing Hospital from January to November 2015 were observed prospectively. There were 19 male and 72 female patients, aging from 25 to 74 years with an average age of (52±12) years. Preoperative ultrasound examination, analysis of intraoperative high definition images, and postoperative pathological examination were used to detect the origins of the parathyroid micro vascular structures and the characteristics of parathyroid specific adipose attachments. Parathyroid specific adipose attachments preserving technique was used in all procedures. The results of parathyroid hormone (PTH), serum calcium and phosphorus were compared pre- and 1-month post-operatively. Paired t test was statistically used to analyze data. Results: Parathyroid micro vascular vessels were closely attached to parathyroid, and they were mainly originated from inside and (or) outside thyroid. Twenty patients received intraoperative high definition images analysis, 62 parathyroids were detected, in which 48 parathyroids (77.4%) had its specific adipose attachments. Lymphatic tissues could be distinguished from adipose tissue using carbon nanoparticles lymphatic tracer technique, which resulted in better preservation of parathyroid specific adipose attachments. There was no significant difference in PTH ((39±17) ng/L vs. (30±16) ng/L), serum calcium ((2.23±0.10) mmol/L vs. (2.20±0.14) mmol/L) and phosphorus ((1.27±0.20) mmol/L vs.(1.26±0.25) mmol/L) pre- and 1-month post-operatively (P>0.05). Conclusions: Preservation of parathyroid specific adipose attachments in total thyroidectomy could result in better protection of parathyroid micro vascular structure and function. It could be benefit to preservation of parathyroid in situ and its function recovery, thus may reduce the incidence of permanent postoperative hypoparathyroidism.

A rare disorder mimics otitis media: Langerhans cell histiocytosis of the temporal bone in a child with interstitial pulmonary fibrosis.

Langerhans cell histiocytosis (LCH) is a rare disease ranging from a benign to a rapidly fatal condition affecting young children predominantly, and is characterized by an abnormal clonal proliferation of Langerhans cells. We report a case of a 3-year-old child presenting with a 1-year history of otorrhea and otorrhagia followed by a 6-month history of postauricular swelling in the right ear. Imaging demonstrated a large mass of organized tissue. A biopsy was conducted, and the diagnosis of LCH was confirmed by histopathological and immunohistochemical examination. The child was treated with a 12-month course of vinblastine chemotherapy with prednisolone. No clinical evidence of recurrence was noticed after 3 years of follow-up. This rare case highlights the importance for otolaryngologists to keep LCH in mind for differential diagnosis in very young patients with symptoms and signs suggestive of acute mastoiditis or chronic otitis media.

Mutations in the gene encoding gap junction protein beta-3 associated with autosomal dominant hearing impairment.

Hearing impairment is the most commonly occurring condition that affects the ability of humans to communicate. More than 50% of the cases of profound early-onset deafness are caused by genetic factors. Over 40 loci for non-syndromic deafness have been genetically mapped, and mutations in several genes have been shown to cause hearing loss. Mutations in the gene encoding connexin 26 (GJB2) cause both autosomal recessive and dominant forms of hearing impairment. To study the possible involvement of other members of the connexin family in hereditary hearing impairment, we cloned the gene (GJB3) encoding human gap junction protein beta-3 using homologous EST searching and nested PCR. GJB3 was mapped to human chromosome 1p33-p35. Mutation analysis revealed that a missense mutation and a nonsense mutation of GJB3 were associated with high-frequency hearing loss in two families. Moreover, expression of Gjb3 was identified in rat inner ear tissue by RT-PCR. These findings suggest that mutations in GJB3 may be responsible for bilateral high-frequency hearing impairment.

Comparison of the effects of alendronate sodium and calcitonin on bone-prosthesis osseointegration in osteoporotic rats.

UNLABELLED: Alendronate (ALO) and calcitonin (CT), as commonly used antiosteoporosis drugs in current clinical practice, have been experimentally confirmed to produce the effectiveness of promoting osseointegration at the interface between prosthesis and host bone and enhancing the long-term stability of the prosthesis. Our current study compared these two drugs' effects on the osseointegration of prosthesis and found that both of them could promote bone attachment between prosthesis and host bone; moreover, ALO produced more pronounced effectiveness. INTRODUCTION: A series of findings confirmed that ALO and CT improved bone attachment of implant in animals. However, which one shows stronger effectiveness has not yet been reported by previous researches. Our study compared the effects of the two commonly used antiosteoporosis drugs on the bone-prosthesis osseointegration so as to provide valuable reference for current clinical options of medication. METHODS: Forty female SD rats aged 5 months were randomly set into A, B, C, and D groups. Except for group A, the others were ovariectomized to establish osteoporosis model (lumbar bone mineral density (BMD) decreased by 20% 4 weeks after ovariectomy). All the rats received prosthesis implantation at their tibial plateau. Then, the rats in groups C and D were given ALO (7 mg/kg/w) orally and CT (5 IU/kg/day) subcutaneously for 12 weeks, respectively. Prior to the execution, application of tetracycline hydrochloride for staining in vivo was done. After harvesting and embedding, the tibia with implants were cut into thin slides, then the bone histomorphometry was measured to observe the new bone around prosthesis and to calculate the osseointegration rate of the implants. By comparison, the effect of the two drugs on osseointegration was evaluated. RESULTS: (1) Both ALO and CT can effectively enhance the volume of bone mass surrounding the hydroxyapatite (HA) prosthesis and also significantly lever up osseointegration rate to 63.7% and 45.7%, respectively (p < 0.05). However, ALO produced more periprosthesis osseointegration rate than CT, with difference of 18% (p < 0.05). (2) The rats' lumber BMD increased in both ALO and CT groups, from 0.081 ± 0.009 and 0.078 ± 0.009 to 0.116 ± 0.008 and 0.109 ± 0.010 g/cm(2), respectively. Moreover, the effect of ALO was observed more pronounced than that of CT. CONCLUSIONS: In osteoporotic conditions, both administration of ALO orally and CT subcutaneously can enhance periprosthesis bone mass and the effects on osseointegration between host bone and prosthesis. Compared with CT, the effect of ALO is more pronounced.

Prognostic model for risk stratification of de novo metastatic nasopharyngeal carcinoma patients treated with chemotherapy followed by locoregional radiotherapy.

BACKGROUND: There is no clinically applicable prognostic model designed for patients with de novo metastatic nasopharyngeal carcinoma (mNPC) treated with chemotherapy followed by locoregional radiotherapy (LRRT). We sought to develop a predictive tool of overall survival for individualized prediction and risk stratification in this heterogeneous patient population. PATIENTS AND METHODS: A total of 244 eligible patients with de novo mNPC, who were treated with platinum-based first-line chemotherapy followed by LRRT, were included in this retrospective study. We divided patients into the training and validation sets based on the date of initial treatment, with 152 patients treated between 2008 and 2013 comprising the training set for model development and 92 patients treated at a later time (2014 to 2015) forming the validation set. We applied Cox proportional hazards model to examine factors associated with overall survival (OS). We developed and subsequently validated a prognostic model to predict OS. We assessed the performance of this prognostic model and stratified patients based on prognostic scores obtained from this proposed model. RESULTS: The median OS of the entire cohort was 60.9 months. C-creative protein, number of metastatic sites, liver metastasis, post-treatment Epstein-Barr virus DNA, and response of metastasis were significantly associated with OS. A prognostic model for individual survival prediction was developed and graphically represented as a nomogram. The model showed favorable discrimination (C-index: 0.759), predictive accuracy [time dependent area under the curve (tAUC) at 5 years: 0.800], and calibration, and was further validated in an independent dataset. A risk stratification derived from the model can stratify these patients into three prognostic subgroups with significantly different survival. CONCLUSION: We developed and validated a prognostic model that exhibited adequate performance in individualized prediction and risk stratification for patients with de novo mNPC treated with chemotherapy followed by LRRT.

[Clavien-Dindo classification of complications after complete mesocolic excision in laparoscopic radical resection of right hemicolon cancer and analysis on its influencing factors].

Objective: To investigate the Clavien-Dindo (CD) classification of complications after complete mesocolic excision (CME) in laparoscopic radical resection of right-sided hemicolon cancer and its influencing factors. Methods: A retrospective case-control study was performed. Inclusion criteria: (1) the adenocarcinoma located at colon from cecum to hepatic flexure; (2) laparoscopic right hemicolectomy with CME was completed. Exclusion criteria: (1) patients had severe organ dysfunction before operation; (2) tumor invaded adjacent organs or developed distant organ metastasis; (3) emergency surgery; (4) failure of laparoscopic surgery, and conversion to laparotomy; (5) without complete clinical data. Finally, clinical data of 141 patients in our hospital form March 2015 to February 2019 were retrospectively analyzed. CD grading standard was used to evaluate postoperative complications. Univariate and multivariate logistic regression analyse were used to analyze the factors that might affect the complications. Survival analysis was conducted by grouping the indicators with statistically significant difference in multivariate analysis. Kaplan-Meier method was used to draw the survival curve and log-rank test was used to analyze the difference. Results: Of the 141 patients, 89 were male and 52 were female with mean age of (61.8±11.0) years. All the operations completed successfully. A total of 37 postoperative complications were developed in 26 (18.4%) patients had postoperative 37 cases of complications, mainly including 7 delayed incision healing, 6 diarrhea, and 5 respiratory dysfunction. According to CD classification standard, grade I, II, and IV a complication rates were 40.5% (15/37), 56.8% (21/37), and 2.7% (1/37) respectively. Univariate analysis showed that age ≥ 65 years (χ(2)=4.338, P=0.037), BMI ≥ 28 kg/m(2) (χ(2)=5.971, P=0.015), and preoperative hemoglobin < 100 g/L (χ(2)=3.985, P=0.046) were risk factors of postoperative complications. Multivariate analysis testified that age ≥ 65 years (OR=7.991, 95%CI: 2.203 to 28.983, P=0.002) and body mass index (BMI) ≥ 28 kg/m(2) (OR=4.231, 95%CI: 1.034 to 17.322, P=0.045) were independent risk factors for complications after laparoscopic CME surgery for right-sided hemicolon cancer. All the patients were followed up for median time of 24 (1-48) months. The log-rank test showed that there were no significant differences in the cumulative survival rate between patients of age < 65 years and age ≥ 65 years (χ(2)=0.986, P=0.321), and between those with BMI < 28 kg/m(2) and BMI ≥ 28 kg/m(2) (χ(2)=0.370, P=0.543). Conclusions: The main complications after CME in laparoscopic radical resection of right hemicolon cancer are CD grade I and II. Elderly and obesity are independent risk factor for postoperative complications. Before the operation, reasonable preventive measures should be taken for the elderly and the obese in order to reduce postoperative complications.

Diagnostic and prognostic significance of long noncoding RNA SSTR5-AS1 in patients with gastric cancer.

OBJECTIVE: Long noncoding RNAs (lncRNAs) display a functional effect on the pathogenesis of several diseases, including various tumors. Herein, we aimed to reveal the role of lncRNA somatostatin receptor 5 antisense RNA 1 (SSTR5-AS1) in gastric cancer (GC). PATIENTS AND METHODS: qRT-PCR was utilized for testing the SSTR5-AS1 expression in 158 paired primary GC tissues and corresponding normal gastric specimens. Receiver operating characteristic (ROC) curves were established to determine the diagnostic values of overexpression of SSTR5-AS1 in GC. A chi-square test was performed to analyze the correlation between SSTR5-AS1 expressions and several clinicopathological features in GC patients. Kaplan-Meier survival curve was constructed to estimate the overall survival (OS) and disease-free survival (DFS). Multivariate analyses were conducted to examine the prognostic value of SSTR5-AS1. RESULTS: We observed that SSTR5-AS1 expression was highly expressed in GC specimens compared with adjacent non-tumor specimens (p < 0.01). High SSTR5-AS1 expression was correlated with an advanced pathologic stage. The ROC curves showed that areas under the ROC curve (AUC) for SSTR5-AS1 is 0.8419. Moreover, high expression of SSTR5-AS1 was observed to be associated with distant metastasis (p = 0.021) and TNM stage (p = 0.042). Besides, survival analysis showed that GC patients with high SSTR5-AS1 expression suffered poorer OS (p = 0.020) and DFS (p = 0.0007). Multivariate assays demonstrated that increased expressions of SSTR5-AS1 could be an independent prognostic marker of OS and DFS of GC patients. CONCLUSIONS: Our findings indicate that SSTR5-AS1 served as a promising novel prognostic biomarker for GC.

[Primary Ewing's sarcoma of the temporal bone: a rare case].

SummaryEwing's sarcoma is a malignant, round cell tumor arising from the bones and primarily affecting children and adolescent. Involvement of the skull bones is rarely reported, constituting 1%-6% of the total Ewing's sarcoma cases. We describe a 33 years old male patient having Ewing sarcoma of the mastoid and petrous parts of temporal bone, whose clinical presentation mimicked mastoiditis with facial nerve palsy. We discuss the clinical and therapeutic course of an extensive primary Ewing sarcoma of the temporal bone and review this entity's literature in detail. The etiopathology of an acute peripheral facial palsy is often hard to identify. If the facial weakness starts together with symptoms suggesting an inflammatory process, the differential diagnosis may be focused first on diseases like herpes zoster oticus and a severe course of acute purulent otitis media. As an uncommon tumor of the temporal bone, physicians should consider Ewing's sarcoma in the differential diagnosis of children and adolescents who present with facial nerve paralysis. And in the case of ambiguous clinical findings, a surgical exposure of the middle ear is recommended.

[The expression of P19ink4d in the pathogenesis and development of hearing loss].

Objective: This study aimed to investigate the P19ink4d expression in cochlea of mice model with noise induced hearing loss and the role of P19ink4d in the degeneration of inner ear cells. It also searched for P19ink4d gene alterations in patients with profound sensorineural deafness.Method: CBA/J mice were exposed to broad band noise at 101 dB SPL for 2 hours, auditory brainstem response (ABR) were examined to confirm noise lead to the permanent threshold shift. Immunohistochemical staining, Western blotting, and real-time polymerase chain reaction (PCR) were performed on cochlear tissues, to elucidate changes in P19ink4d expression in mice after noise exposure. For clinical evaluation, 400 children from unrelated families with severe or profound sensorineural hearing loss (SNHL) were recruited, genomic DNA was obtained from the patients and was subjected to DNA microarray to screen mutations in 4 most common genes. The sample that carried none of the common mutant alleles were subjected to PCR and sequenced to detect mutations in P19ink4d gene.Result: The ABR threshold shift of mice in the experimental group significantly increased after noise exposure and was higher than that in the null-noise group. The ABR of 1 day post noise was least among experimental groups and there is no statistical different between ABR of 7 days and 14 days post noise. The missing of outer hair cells occurred after noise exposure, while the inner hair cells hardly miss. It was found that the P19ink4d expression increased significantly in the inner ear cells 3 hours after noise exposure, then recovered in 24 hours. Western blot indicated that the amount of P19ink4d increased transitorily 3-6 h after the noise. However, no mutation existed within the coding exons of P19ink4d in the patients with profound sensorineural deafness.Conclusion: The results support the concept that P19ink4d may play an important role in the pathogenesis and development of noise induced hearing loss.

[Analysis of the application and funding projects of National Natural Science Foundation of China in the field of burns and plastic surgery from 2010 to 2016].

We analyzed the data of application and funding projects of the National Natural Science Foundation of China (NSFC) during 2010-2016 in the field of burns and plastic surgery and summarized the NSFC funding pattern, the research hotspots, and weaknesses in this field. The NSFC has funded 460 projects in the field of burns and plastic surgery, with total funding of RMB 227.96 million. The scientific issues involved in the funding projects include orthotherapy against malformations, wound repair, basic research of burns, skin grafting, scars prevention, and regeneration of hair follicle and sweat glands. The research techniques involved in the funding projects are diversified. NSFC plays an important role in the scientific research and talents training in the field of burns and plastic surgery.

Survey of intestinal parasites in pigs from intensive farms in Guangdong Province, People's Republic of China.

The prevalence of intestinal parasites was investigated in intensive pig farms in Guangdong Province, China between July 2000 and July 2002. Faecal samples from 3636 pigs (both sexes and five age groups) from 38 representative intensive pig farms employing different parasite control strategies were examined for the presence of helminth ova and protozoan oocysts, cysts and/or trophozoites using standard techniques. Of the 3636 pigs sampled, 209 (5.7%) were infected with Trichuris suis, 189 (5.2%) with Ascaris, 91 (2.5%) with Oesophagostomum spp., 905 (24.9%) with coccidia (Eimeria spp. and/or Isospora suis) and 1716 (47.2%) with Balantidium coli. These infected pigs were mainly from farms without a strategic anti-parasite treatment regime. Concurrent infection of multiple parasites was common, and T. suis was the most common nematode infecting breeding, young and mature pigs. The results of the present investigation provide relevant 'base-line' data for assessing the effectiveness of control strategies against intestinal parasitism in intensively raised pigs in Guangdong Province, China.

The utility of MRI for pre-operative T and N staging of gastric carcinoma: a systematic review and meta-analysis.

OBJECTIVE: To perform a meta-analysis and literature review regarding the diagnostic accuracy of MRI for pre-operative tumour depth invasion (T) and regional lymph node invasion (N) staging of gastric carcinoma (GC). METHODS: Articles were identified through systematic search of Medline, PubMed, Cochrane Library, Web of Science, Springerlink and several Chinese databases. The study quality was assessed by the quality assessment for studies of diagnostic accuracy. 2 reviewers independently extracted and assessed the data from 11 eligible studies. A meta-analysis was then carried out. Subgroup and sensitivity analyses were also performed. RESULTS: 11 studies (439 patients) were finally included in the current review. Among these studies, the significant evidence of heterogeneity was only discovered for specificity in T4 stage (I(2) = 59.8%). Pooled sensitivity and specificity of MRI to diagnose T stage tumour (T3-4 vs T1-2) were 0.93 [95% confidence interval (CI), 0.89-0.96] and 0.91 (95% CI, 0.87-0.95), respectively. Pooled estimates of sensitivity and specificity of MRI to diagnose N stage tumour (N0 vs N+) were 0.86 (95% CI, 0.80-0.92) and 0.67 (95% CI, 0.54-0.79), respectively. Subgroup analyses showed that diffusion-weighted imaging was more helpful for T staging. CONCLUSION: The present systematic review suggests that MRI has a good diagnostic accuracy for pre-operative T staging of GC and should be widely used in clinical work. However, the ability for N staging is relatively poor on MRI. ADVANCES IN KNOWLEDGE: In the pre-operative staging of GC, MRI was a useful tool and may enhance accuracy for the T staging of advanced GC.

Tonic efferent-induced cochlear damping in roosting and echolocating mustached bats.

The activity of the medial olivocochlear (MOC) efferent system in mustached bats, Pteronotus p. parnellii, was studied by monitoring changes in the mechanical properties of the cochlea. The changing properties were expressed by the decay time (DT) of cochlear microphonic potentials produced by transient-induced ringing (Henson et al., 1995). Tape-recorded roost noise (biosonar and communication sounds) produced sudden, marked decreases in DT when presented to the contralateral ear of animals adapted to the quiet. When the animals were first removed from their roosts the DT was relatively short (1.2-1.5 ms) but this gradually lengthened by about 0.5-1.0 ms as they rested in a quiet chamber. The time required to reach a stable, quiet-adapted state after noise exposure varied with SPL and exposure time; in many experiments recovery was in the range of 90-120 min. When quiet-adapted bats were isolated and allowed to fly and echolocate for 20 min, the DTs measured within a few minutes after the end of the flight were also short and only slowly returned to longer preflight values. The administration of a single dose of gentamicin, which blocks MOC effects, greatly reduced the amount of suppression (damping) observed after periods of noise and echolocation sound exposure. We conclude that tonic MOC activity is induced by the natural vocalizations and roost noise and this activity probably regulates and protects the highly resonant cochlear partition.

AChE-staining of type II ganglion cells, processes and terminals in the cochlea of the mustached bat.

There have been a number of reports showing that ganglion cells of sensory neurons may be stained by traditional acetylcholinesterase (AChE) histochemical techniques commonly used to demonstrate efferent nerve fibers and terminals. AChE-staining has been described for cell bodies in the vestibular and spiral ganglia; staining of peripheral and central processes, however, is rare and the presence of reaction product in afferent terminals has not been reported. The outer hair cells of mustached bats, Pteronotus parnellii, differ from those of most mammals in that they typically have a single, large efferent terminal surrounded by 5-7 small, afferent terminals. In this animal an AChE-positive reaction was found not only in efferent fibers and terminals but also in type II ganglion cells, their peripheral and central processes and in outer hair cell terminals. The stained cell bodies were smaller than the unstained type I ganglion cells and they were much fewer in number. The processes of the stained cells could be followed from the soma. The central processes were dispersed throughout the VIIIth nerve trunk. Stained peripheral processes were evident in the osseous spiral lamina, floor of the tunnel of Corti and first space of Nuel and in the outer spiral plexus along the sides of the outer phalangeal (Deiters') cells. AChE-stained afferent terminals were easy to identify after transection of the crossed olivocochlear bundle (COCB) and subsequent degeneration of large efferent terminals. These results are of interest in that assessments of efferent nerve histochemistry after COCB transection need to recognize the potential contribution of AChE reaction product in afferent terminals.(ABSTRACT TRUNCATED AT 250 WORDS)

Efferent terminals in the cochlea of the mustached bat: quantitative data.

Efferent terminals in the cochlea of the mustached bat were stained for acetylcholinesterase (AChE) and quantitative data were obtained for the number and size of the endings on the outer hair cells (OHCs) in each row, from base to apex. From TEM micrographs and AChE-stained, surface preparations it was determined that every OHC had a single, large terminal. The mean size of the terminals was significantly different in each row, with the largest occurring in the first row (7.1 microns 2); the mean size in the second and third rows was 5.7 and 5.0 microns 2 respectively. In specific frequency processing regions, the largest mean size (8.4 microns 2) for first row OHCs was consistently found in the distal densely innervated (DDI) area. This region has afferent neurons that are sharply tuned to the second harmonic, constant frequency component of the bat's biosonar signals. Sudden changes in the size of the terminals were observed exactly at the boundaries of the DDI with adjacent sparsely innervated regions. Similar, but less striking, size changes also occurred in and adjacent to the proximal densely innervated (PDI) region, a harmonically related, sharply tuned region, which processes the bat's 91.5 kHz, third harmonic, constant frequency signals. The region of the cochlea with the smallest first row terminals (mean 5.3 microns 2) was the large, sparsely innervated region of the basal turn, a region that does not appear to process biosonar signals. Although the significance of differences in efferent terminal size is not known, the data suggest a possible correlation between OHC stimulation and sharp tuning. The potentially greater influence of the efferent fibers on the first row of OHCs, compared to other rows, is consistent with observations made on other mammals; in the latter, however, the greater influence has been suggested more by number than size. Unlike other mammals, the OHC efferents in the mustached bat have no clear base-to-apex gradient in the number or size of the efferent terminals. It is suggested that this might reflect the high frequency nature of the ear (6-120 kHz) and absence of low frequency hearing.

The effect of contralateral stimulation on cochlear resonance and damping in the mustached bat: the role of the medial efferent system.

In the unanesthetized mustached bat, stimulation of the ear with an acoustic transient produces damped oscillations which are evident in the cochlear microphonic potential. In this report we demonstrate how the decay time of these oscillations is affected by broadband noise presented to the contralateral ear (CLN). In the absence of CLN, the mean decay time was 1.94 +/- 0.23 ms, but during the presentation of CLN the decay time consistently decreased. The changes were finely graded, the higher the CLN, the greater the change. The effect could be maintained at a constant level for extended periods of time and this was evident when the CLN exceeded 40 dB SPL. The latency of the reflex for 64 dB noise was about 11 ms and near maximum changes occurred within 15 ms of CLN onset. Sectioning medial efferent nerve fibers in the floor of the fourth ventricle or the administration of a single dose of gentamicin eliminated changes produced by CLN. The prominence of CM responses to damped oscillations and the robust changes in response to CLN make the mustached bat an excellent model for studying the influence of the medial efferent system on cochlear mechanics.