Therapeutic value of lymph node dissection for Siewert type II and III adenocarcinoma: meta-analysis

BACKGROUND

Adenocarcinoma of the oesophagogastric junction presents an increasing incidence. Surgical resection with lymphadenectomy is the only curative treatment modality at the present time, but the optimal extent of lymphadenectomy is debatable. The aim of the present meta-analysis was to estimate the therapeutic value of each nodal station.

METHODS

Studies reporting the therapeutic value index of each nodal station in Siewert types II/III oesophagogastric junction (EGJ) were searched in PubMed, Web of Science and Embase up to October 2022. This index was calculated by multiplication of metastatic incidence and 5-year overall survival rate at each nodal station. Risk of bias was assessed using the Joanna Briggs Institute Critical Appraisal Checklist for Prevalence Studies. Pooled metastatic incidence and therapeutic value index were calculated using RevMan 5.4.

RESULTS

Twelve studies involving 3513 patients were included. Nodes No. 3, 1, 7 and 2 were routinely dissected and achieved a high (≥10) or moderate (5-10) therapeutic value index in decreasing order, due to their high metastatic incidence and favourable survival rate. The index was relatively low (2-5) in suprapancreatic nodes No. 9, 11p and 8a. The index for nodes No. 4d and 10 was relatively low in Siewert type Ⅲ EGJ but very low (<2) in type Ⅱ. The index was very low for nodes No. 5, 6, 11d and 12a, due to their low metastatic incidence and poor survival if positive. Para-aortic, parahiatal and mediastinal nodes were dissected only in highly selected cases. Dissection of the lower mediastinal nodes, especially No. 110, could improve survival rates in type Ⅱ EGJ.

CONCLUSION

These data could help assess the optimal extent of lymphadenectomy for EGJ. Nodes No. 1, 2, 3, 7, 8a, 9 and 11p need routine dissection in both Siewert types Ⅱ/Ⅲ EGJ; nodes around the lower oesophagus (especially No. 110) in Siewert type Ⅱ EGJ and nodes No. 4d and 10 in Siewert type Ⅲ EGJ might be considered for dissection.

[Genomic epidemiology of Vibrio parahaemolyticus from acute diarrheal patients in Shenzhen City from 2013 to 2021]

Objective: To characterize the prevalence and genomic epidemiology of Vibrio parahaemolyticus from acute diarrheal patients in Shenzhen City from 2013 to 2021. Methods: Based on the Shenzhen Infectious Diarrhea Surveillance System, acute diarrheal patients were actively monitored in sentinel hospitals from 2013 to 2021. Whole-genome sequencing (WGS) of Vibrio parahaemolyticus isolates was performed, and the genomic population structure, serotypes, virulence genes and multilocus sequence typing were analyzed. Outbreak clusters from 2019 to 2021 were explored based on single-nucleotide polymorphism analysis. Results: A total of 48 623 acute diarrhea cases were monitored in 15 sentinel hospitals from 2013 to 2021, and 1 135 Vibrio parahaemolyticus strains were isolated, with a positive isolation rate of 2.3%. Qualified whole-genome sequencing data of 852 isolates were obtained. Eighty-nine serotypes, 21 known ST types and 5 new ST types were identified by sequence analysis, and 93.2% of strains were detected with toxin profile of tdh+trh-. 8 clonal groups (CGs) were captured, with CG3 as the absolute predominance, followed by CG189. The CG3 group was dominated by O3:K6 serotype and ST3 sequence type, while CG189 group was mainly O4:KUT, O4:K8 serotypes and ST189a and ST189 type. A total of 13 clusters were identified, containing 154 cases. About 30 outbreak clusters with 29 outbreak clusters caused by CG3 strains from 2019 to 2021. Conclusion: Vibrio parahaemolyticus is a major pathogen of acute infectious diarrhea in Shenzhen City, with diverse population structures. CG3 and CG189 have been prevalent and predominant in Shenzhen City for a long time. Scattered outbreaks and persistent sources of contamination ignored by traditional methods could be captured by WGS analysis. Tracing the source of epidemic clone groups and taking precise prevention and control measures are expected to significantly reduce the burden of diarrhea diseases caused by Vibrio parahaemolyticus infection in Shenzhen City.

[Comparison of follow-up treatment regimens for colorectal cancer liver metastases without objective response to neoadjuvant chemotherapy: direct surgery or surgery after second-line chemotherapy]

Objective: To compare the effect of direct surgery or surgery after second-line chemotherapy for colorectal cancer patients with liver metastases who did not achieve objective remission after neoadjuvant chemotherapy. Methods: A retrospective case cohort study was used. The clinical and pathological data of 107 patients with colorectal cancer liver metastases who did not achieve objective response to neoadjuvant chemotherapy at Department of Hepatobiliary Surgery,Cancer Hospital,Chinese Academy of Medical Sciences from December 2008 to December 2016 were retrospectively collected. There were 71 males and 36 females, median age was 57 years (range: 28 to 79 years). According to the different treatment regimens after neoadjuvant chemotherapy,107 cases were divided into a direct surgery group (direct group,n=65) and an operation after receiving second-line chemotherapy group (second-line group,n=42). The propensity score matching(PSM) of the Logistic regression model was used to match the bilobar distribution of liver metastases and the number of first-line chemotherapy cycles in the two groups of patients. The caliper value was set to 0.10 and the matching ratio was 1∶2. T test, Mann-Whitney U test, χ² test or Fisher's exat test was used to analyzed the data between the tuo groups, respectively. Survival analysis design was used to investigate the difference in prognosis between the two groups of patients. Results: The follow-up time(M(IQR)) was 56.3(34.3) months (range: 2.1 to 95.0 months),and all patients were followed up. After PSM,there were 28 cases in the direct group and 42 cases in the second-line group, there were no significant differences in whether R0 resection was feasible,blood loss,blood transfusion,postoperative complications and postoperative hospital stay between the two groups (all P>0.05). The 1,3,and 5-year progression-free survival(PFS) rates of the direct group were 40.0%,16.5%,and 11.0%,and the 1,3,and 5-year overall survival(OS) rates were 98.5%,61.2%,and 41.4%,respectively, the second-line group 1,3,5 years PFS rates were 35.7%,14.3%,14.3%,1,3,5-year OS rate were 95.2%,55.1%,44.4%,respectively. The median PFS time of the direct group and the second-line group was 8.5 months and 7.5 months,respectively,and the difference was not statistically significant (P=0.826). The median OS time of the direct group and the second-line group were 33.8 months and 46.9 months,respectively. The difference was not statistically significant(P=0.646).The median PFS time of the direct group and second-line chemotherapy complete remission and partial remission group(CR/PR group) was 10.2 months and 9.1 months,respectively,and the difference was not statistically significant(P=0.669). The median OS time of the direct group and the second-line CR/PR group was 51.0 months and 46.9 months,respectively,and the difference was not statistically significant(P=0.427). The results of survival analysis suggested that major liver resection was an independent prognosis factor for PFS (HR=1.809,95%CI: 1.067 to 3.067,P=0.028) and OS(HR=2.751,95%CI: 1.317 to 5.747,P=0.007). Second-line chemotherapy was not an independent prognostic factor for PFS (HR=0.945, 95%CI:0.570 to 1.567,P=0.828) and OS (HR=0.866,95%CI: 0.468 to 1.602,P=0.646). Conclusions: There is no significant difference in the short-term outcome and long-term prognosis between direct surgery patients and second-line chemotherapy followed by surgery. Second-line chemotherapy is not an independent prognostic factor for colorectal cancer liver metastases patients who fail to achieve objective response after neoadjuvant chemotherapy.

[Effects of intermittent hypoxia intestinal bacterial translocation on mesenteric lymph node injury]

Objective: To observe the effect of intermittent hypoxia on intestinal bacterial translocation and mesenteric lymph node (MLN) structure and explore its mechanism. Methods: Twenty-four adult male Wistar rats were randomly divided into an experimental group (HI group) and a control group (UC group), with 12 rats in each. During the experiment, both groups were fed under the same conditions, but the HI group received simulated sleep apnea with hypoxic treatment. On the last day of the 2nd and 4th week of the experiment, 20% urethane(0.7 ml/100g) was used for anesthesia, and MLNs and corresponding small intestinal tissues were aseptically collected.HE staining was used to observe the microscopic changes of the tissues. The lymph node tissue was sent for pathogenic culture. The levels of oxide dismutase (SOD), lipid peroxide (MDA) and reactive oxygen species (ROS) were measured for the extent of oxidative stress. Serum diamine oxidase (DAO) was measured to assess the extent of intestinal mucosal damage. Result: MLNs and their corresponding small intestines were damaged in the HI group as compared to the UC group. With the prolongation of intermittent hypoxic time, the number of germinal centers in MLNs was significantly reduced, with the volume reduced, cortical medullary fusion aggravated, and the area ratio increased. The intestinal tissue showed severe damage to the intestinal epithelium, increased permeability, mucosal edema, and changes of the crypts. At the 4th week, MLNs in the HI group grew Clostridium perfringens under anaerobic conditions, confirming intestinal bacterial translocation. The contents of ROS, SOD and MDA in MLNs of the HI group were significantly higher than those in the UC group (P<0.05). At the 2nd week and the 4th week, the contents of ROS, SOD and MDA were not significantly changed in the UC group(P>0.05). While the content of ROS and MDA in MLNs of the HI group at 4th week was significantly higher than that in the second week (P<0.05), but no change of SOD was observed (P>0.05). Serum DAO levels in the HI group were higher than those in the UC group at week 2 and week 4 (P<0.05), suggesting that the degree of intestinal mucosal injury in the HI group was more serious than that in the UC group. Conclusion: Hypoxic exposure aggravated the degree of oxidative stress in rats. With the prolongation of intermittent hypoxia, the intestinal mucosa of rats was seriously damaged. The intestinal flora shifted to damage the structure of mesenteric lymph nodes, and oxidative stress was further aggravated, which in turn affected the integrity of the intestinal autoimmune function.

LINC01235-TWIST2 feedback loop facilitates epithelial-mesenchymal transition in gastric cancer by inhibiting THBS2

Although the anomalous expression of long non-coding RNAs (lncRNAs) has been extensively investigated in numerous carcinomas including gastric cancer (GC), their function remains unclear. The aim of our study was to explore the role of LINC01235 in GC. We used real-time quantitative PCR (RT-qPCR) to measure the expression of LINC01235 and twist family bHLH transcription factor 2 (TWIST2) in GC tissues. Scratch and transwell assays were performed to evaluate cellular capacity for migration and invasion. Gene relationships were explored by Weighted Gene Co-Expression Network Analysis (WGCNA). We measured TWIST2, thrombospondin 2 (THBS2) and epithelial-mesenchymal transition (EMT)-related proteins with western blot. We also used Pearson correlation analysis and the Kaplan-Meier method to detect associations among genes and overall survival. We found that LINC01235 was upregulated in GC tissues and cells. LINC01235 down-regulation restricted migration and invasion. Interestingly, we found the LINC01235-TWIST2-THBS2 axis induced EMT. Additionally, TWIST2 upregulated LINC01235 transcription in luciferase and chromatin immunoprecipitation (ChIP) assays. Bioinformatics analysis showed that microRNA (miR)-6852-5p might be a key gene involved in the regulation of TWIST2 by LINC01235. The LINC01235-TWIST2 positive feedback loop mainly affected migration and invasion of GC cells, which suggests it may serve as a potential therapeutic target in gastric cancer.

A research of STEAP1 regulated gastric cancer cell proliferation, migration and invasion in vitro and in vivos

Six‐Transmembrane Epithelial Antigene of the Prostate 1 (STEAP1) is associated with the occurrence and development of cancer. This study aimed to clarify the role of STEAP1 in gastric cancer tumour growth and metastasis, as well as its molecular mechanism of action.Statistical methods were used for clinical data analysis. Protein expression was detected using immunohistochemistry(IHC). The mRNA and protein expression in the cell cultures were detected using reverse transcription‐polymerase chain reaction(RT‐PCR) and western blot analysis. Overexpression and silencing models were constructed using plasmid and lentivirus transfection. To detect cell proliferation in vitro, Cell Counting Kit‐8(CCK‐8), flow cytometry and colony formation assays were used; transwell and wound healing assays were used to detect cell migration and invasion;For in vivo experiments, nude BALB/c mice were used for detecting subcutaneous tumorigenesis and intraperitoneal implantation. In the results,we found STEAP1 was overexpressed in gastric cancer tissues and cell lines. Single‐factor and Cox analyses showed that STEAP1 gene expression level correlated with poor prognosis. Up‐regulation of STEAP1 increased cell proliferation, migration and invasion, which decreased after STEAP1 was knocked down. These changes were achieved via the activation of the AKT/FoxO1 pathway and epithelial‐mesenchymal transformation (EMT). The in vivo animal experiments showed that STEAP1 knock down, resulted in a decrease in the subcutaneous tumour and peritoneal tumour formation.

[Progress in studies on obstructive sleep apnea and intestinal microecological balance]

SummaryObstructive sleep apnea （OSA） is closely related to the development of various diseases. Hypoxic perfusion caused by OSA can mediate the occurrence of inflammatory reactions or aggravate metabolic disorders to affect intestinal microecological balance. Intestinal bacteria can participate in the development of inflammatory reaction or metabolic disorder by itself or its components, and the oxidative stress reaction of the body develops in a vicious circle. The mechanism has not yet been fully elucidated, so we reviewed the research progress on OSA and intestinal microecological balance.

[Diagnostic efficiency of NO/ET-1 and HCY level in severe OSAHS patients with cognitive impairment]

Objective:To investigate the diagnostic efficiency of HCY and NO/ET-1 to cognitive dysfunction in patients with severe obstructive sleep apnea hypopnea syndrome, and to interfere with the cognitive function of severe OSAHS patients. Method: Eighty-six patients with OSAHS were divided into mild group (22 cases), moderate group (23 cases), severe group (41 cases) and healthy physical examination group (50 cases). The levels of serum HCY and NO/ET-1 were compared between the four groups. The Montreal cognitive assessment scale was used to evaluate the incidence of mild cognitive impairment in severe OSAHS group, and the correlation between the level of serum HCY, NO/ET-1 and cognitive function in severe OSAHS group was analyzed. Result:The level of serum HCY in patients with severe OSAHS with cognitive impairment was(32.28±3.92)μmol/L, higher than that of the cognitive moderate group(26.34±4.05)μmol/L, and mild group (18.62±3.29)μmol/L. The level of serum NO/ET-1 in patients with severe OSAHS with cognitive impairment was (0.69±0.19), higher than that of the cognitive moderate group(2.76±0.28), and mild group (3.98±0.37), the difference was statistically significant (P<0.05). In severe group, there was a negative correlation between the level of serum HCY and the score of MoCA and its subscores (P<0.05), and there was a positive correlation between the total scores of NO/ET-1 and MoCA and their subscores (P<0.05), and negative correlation between HCY and NO/ET-1 (P<0.05). The area under the ROC curve of predicting serum HCY and NO/ET-1 levels in severe OSAHS patients with cognitive impairment were 0.788(95%CI0.654-0.921) and 0.770 (95%CI0.642-0.899). Conclusion:Serum HCY and NO/ET-1 were the factors influencing the formation of cognitive impairment in severe OSAHS patients. The level of HCY was negatively correlated with the degree of cognitive impairment, and NO/ET-1 was positively correlated with the degree of cognitive impairment.

Hepatitis C virus upregulates B-cell receptor signaling: a novel mechanism for HCV-associated B-cell lymphoproliferative disorders

B-cell receptor (BCR) signaling is essential for the development of B cells and has a critical role in B-cell neoplasia. Increasing evidence indicates an association between chronic hepatitis C virus (HCV) infection and B-cell lymphoma, however, the mechanisms by which HCV causes B-cell lymphoproliferative disorder are still unclear. Herein, we demonstrate the expression of HCV viral proteins in B cells of HCV-infected patients and show that HCV upregulates BCR signaling in human primary B cells. HCV nonstructural protein NS3/4A interacts with CHK2 and downregulates its activity, modulating HuR posttranscriptional regulation of a network of target mRNAs associated with B-cell lymphoproliferative disorders. Interestingly, the BCR signaling pathway was found to have the largest number of transcripts with increased association with HuR and was upregulated by NS3/4A. Our study reveals a previously unidentified role of NS3/4A in regulation of host BCR signaling during HCV infection, contributing to a better understanding of the molecular mechanisms underlying HCV-associated B-cell lymphoproliferative disorders.

Photoinduced Formation of Peroxide Ions on La2O3 and Nd2O3 under O2: Effects of Excitation Wavelength and Crystal Structure

Photoinduced formation of peroxide ions on La2O3 and Nd2O3 under O2 was studied by in-situ microprobe Raman spectroscopy with attention focused on the effect of excitation wavelength and crystal structure on the O2(2-) formation. It was found that photoexcitations at 633, 532, 514, and 325 nm can induce O2(2-) formation over La2O3 at 450 °C. By contrast, photoexcitation at 785 nm does not cause formation of O2(2-) up to 500 °C. Photoexcitation at 325 nm can induce O2(2-) formation on cubic Nd2O3 at 25 °C, but cannot induce O2(2-) formation on hexagonal Nd2O3 up to 200 °C. The significant difference in the behavior of O2(2-) formation over the Nd2O3 samples of the two structures can be related to the difference in the capacity to adsorb O2. Since the number of oxygen vacancies in cubic Nd2O3 is larger than that in the hexagonal one, the former has a higher capacity than the latter to adsorb O2. As a result, cubic Nd2O3 is more favorable to the reaction of O2 with O(2-) to generate O2(2-). The structural similarity between cubic Nd2O3 and Nd2O2(O2) may be another factor in favor of peroxide formation.

Separation of phytic acid and other related inositol phosphates by high-performance ion chromatography and its applications

A high-performance anion-exchange chromatographic method was developed for the separation of phytic acid and other inositol phosphates (myo-inositol bis-, tris-, tetrakis-, and pentakisphosphates) with gradient elution and ultraviolet absorbance detection after post-column derivatization. With the acidic eluents, the combination of anion-exchange and ion suppression retention mechanisms led to the separation of 35 inositol phosphates (excluding enantiomers) into 27 peaks for the first time, and the retention behaviors of all myo-inositol bis- to hexakisphosphate isomers were studied. The whole separation procedure was completed within 65 min. Based on the investigations of nonenzymatic hydrolysis of phytic acid under different conditions by using this method, an in-house reference standard solution was produced, which can be used for method development. In addition, by applying this method to in vitro kinetic studies, at least one new enzymatic hydrolysis pathway of phytic acid was found, and one rule of enzymatic dephosphorylation of inositol phosphates (position effect) was proposed and another one (neighboring effect) was confirmed. The principle of the proposed identification approach for several inositol phosphate isomers based on hydrolysis products study will be applicable to other natural products analysis, for which standards are very expensive or not available.

Simultaneous determination of artificial sweeteners, preservatives, caffeine, theobromine and theophylline in food and pharmaceutical preparations by ion chromatography

A novel ion chromatographic method was proposed for the simultaneous determination of artificial sweeteners (sodium saccharin, aspartame, acesulfame-K), preservatives (benzoic acid, sorbic acid), caffeine, theobromine and theophylline. The separation was performed on an anion-exchange analytical column operated at 40 degrees C within 45 min by an isocratic elution with 5 mM aqueous NaH2PO4 (pH 8.20) solution containing 4% (v/v) acetonitrile as eluent, and the determination by wavelength-switching ultraviolet absorbance detection. The detection limits (signal-to-noise ratio 3:1) for all analytes were below the sub-microg/ml level. Under the experimental conditions, several organic acids, including citric acid, malic acid, tartaric acid and ascorbic acid, did not interfere with the determination. The method has been successfully applied to the analysis of various food and pharmaceutical preparations, and the average recoveries for real samples ranged from 85 to 104%. The levels of all analytes determined by this method were in good agreement with those obtained by the high-performance liquid chromatographic procedure. The results also indicated that ion chromatography would be possibly a beneficial alternative to conventional high-performance liquid chromatography for the separation and determination of these compounds.

An electrophysiological study of neural pathways for corticofugally inhibited neurons in the central nucleus of the inferior colliculus of the big brown bat, Eptesicus fuscus

This electrophysiological study tests the hypothesis that one possible neural pathway for corticofugally inhibited neurons in the central nucleus of the inferior colliculus (ICc) of the big brown bat, Eptesicus fuscus, is mediated through excitatory projections from the auditory cortex (AC) to the external nucleus of the IC (ICx), which then sends inhibitory inputs to the ICc. This study shows that all neurons in the ICx are broadly tuned to stimulus frequency. Electrical stimulation in the AC typically increases the number of impulses, expands the auditory spatial response areas, and broadens the frequency tuning curves (FTCs) of neurons in the ICx. This corticofugal facilitation is mediated at least in part through NMDA receptors, since application of DL-2-amino-5-phosphonovaleric acid (APV), an antagonist for NMDA, decreases these response properties of neurons in the ICx. Electrical stimulation in the ICx typically decreases the number of impulses, reduces the auditory spatial response areas, and narrows the FTCs of neurons in the ICc. This inhibition is mediated at least in part through GABAA receptors, since application of bicuculline, an antagonist for GABA, increases these response properties of neurons in the ICc. These data suggest that corticofugal facilitation of the ICx and the inhibition of the ICx to the ICc may be one of the polysynaptic pathways for corticofugal inhibition of neurons in the ICc. Possible functions of this polysynaptic pathway in acoustic orientation and signal processing are discussed.

[Simultaneous determination of various food additives by high performance liquid chromatography]

A novel method is proposed for the simultaneous separation and determination of eight food additives, acesulfame potassium (AK), aspartame (ASP), benzoic acid (BA), caffeine (CA), saccharin sodium (SA), sorbic acid (SOR), theobromine (TB) and theophylline (TP) by reversed-phase high performance liquid chromatography. The separation was achieved within 23 min by using an Alltech Econosphere C18 column with 10 mmol/L NaH2PO4(pH 4.00)-acetonitrile (90:10, V/V) as mobile phase. The qualification and quantitation were accomplished by using a photodiode array detector. The detection limits (S/N = 3) for all analytes were below mg/L level. Under the experimental conditions, other common food additives and organic acids such as cyclamate, citric acid, malic acid, tartaric acid and ascorbic acid, did not interfere with the determination. The method has been successfully applied to the analysis of various foods as well as pharmaceutical preparation, and the average recoveries for real samples ranged from 78.5% to 107.2%.

Bicuculline application affects discharge patterns, rate-intensity functions, and frequency tuning characteristics of bat auditory cortical neurons

This study examined the effect of bicuculline application on the auditory response properties in the auditory cortex of the big brown bat, Eptesicus fuscus. All auditory cortical neurons studied discharged either 1-2 or 3-7 impulses to 4 ms sound stimuli. Cortical neurons with high best frequencies tended to have high minimum thresholds. Bicuculline application increased the number of impulses and shortened the response latencies of all cortical neurons as well as changing the discharge patterns of half of the cortical neurons studied. Bicuculline application raised the rate-intensity functions but lowered the latency-intensity functions to varying degrees. Threshold-frequency tuning curves (FTCs) were either V-shaped, upper threshold or double-peaked. Threshold-FTCs and impulse-FTCs were mirror-images of each other. Bicuculline application expanded and raised the impulse-FTCs but lowered the threshold-FTCs, resulting in significantly decreased Q(n) values. Threshold-FTCs of cortical neurons determined within an orthogonally inserted electrode were very similar and expanded FTCs during bicuculline application were also very similar. Possible mechanisms for the contribution of GABAergic inhibition to shaping these response properties of cortical neurons are discussed.

[The latest applications of ion chromatography in food analysis]

The latest applications of ion chromatography in food analysis is reviewed with 60 references, and the development trend in this aspect is also discussed.

Determination of eight synthetic food colorants in drinks by high-performance ion chromatography

Eight synthetic food colorants (Amaranth, Brilliant Blue, Indigo Carmine, New Red, Ponceau 4R, Sunset Yellow, Tartrazine, Allura Red) were determined by high-performance ion chromatography on an anion-exchange analytical column with very low hydrophobicity and visible absorbance detection. Gradient elution with hydrochloric acid-acetonitrile effected both the chromatographic separation of these colorants and the on-line clean-up of the analytical column, which was very advantageous for routine analysis. High-performance ion chromatography may be a solution to the chromatographic analysis for some water-soluble, organic analytes with strong hydrophobicity. The method has been applied to the determination of colorants in drinks and in instant drink powder. No time-consuming pretreatment, as used in conventional liquid chromatography, was needed.

Corticofugal regulation of auditory sensitivity in the bat inferior colliculus

Under free-field stimulation conditions, corticofugal regulation of auditory sensitivity of neurons in the central nucleus of the inferior colliculus of the big brown bat, Eptesicus fuscus, was studied by blocking activities of auditory cortical neurons with Lidocaine or by electrical stimulation in auditory cortical neuron recording sites. The corticocollicular pathway regulated the number of impulses, the auditory spatial response areas and the frequency-tuning curves of inferior colliculus neurons through facilitation or inhibition. Corticofugal regulation was most effective at low sound intensity and was dependent upon the time interval between acoustic and electrical stimuli. At optimal inter-stimulus intervals, inferior colliculus neurons had the smallest number of impulses and the longest response latency during corticofugal inhibition. The opposite effects were observed during corticofugal facilitation. Corticofugal inhibitory latency was longer than corticofugal facilitatory latency. Iontophoretic application of gamma-aminobutyric acid and bicuculline to inferior colliculus recording sites produced effects similar to what were observed during corticofugal inhibition and facilitation. We suggest that corticofugal regulation of central auditory sensitivity can provide an animal with a mechanism to regulate acoustic signal processing in the ascending auditory pathway.

The effect of pulse repetition rate, pulse intensity, and bicuculline on the minimum threshold and latency of bat inferior collicular neurons

This study examines the effect of pulse repetition rate (PRR), pulse intensity, and bicuculline on the minimum threshold (MT) and latency of inferior collicular neurons of the big brown bat, Eptesicus fuscus, under free-field stimulation conditions. It tests the hypothesis that changes in MT and latency of collicular neurons are co-dependent on PRR. The number of impulses in inferior collicular neurons (n = 245) increased either monotonically (25%) or non-monotonically (75%) with pulse intensity. Latencies either decreased to a plateau (72%), fluctuated unpredictably within 3 ms (21%) or changed very little (7%) with increasing pulse intensity. Latencies and MTs of most collicular neurons increased by 1.5-24 ms (mean +/- SD = 4.8 +/- 3.3 ms) and 4-75 dB (mean +/- SD = 22.1 +/- 16.2 dB) with increasing PRR. In most neurons (94%), the latency increase was completely (42%) or partially (52%) eliminated when pulse intensity was compensated for the MT increase with PRR. Complete elimination of latency was achieved by bicuculline application. In a few neurons (6%), the latency increase with PRR was not affected by compensated pulse intensity or bicuculline application.

Sound pressure transformation at the pinna of Mus domesticus

Sound pressure transformation properties at the pinna of laboratory mice. Mus domesticus, were studied by measuring the sound pressure level of continuous tone at a series of frequencies at the tympanic membrane as a function of the position of a sound source under free-field stimulation conditions. Sound pressure transformation functions showed some prominent spectral notches throughout the frequency range of 10-80 kHz tested. When delivered from some angles within the ipsilateral frontal hemisphere, the sound pressure at the tympanic membrane of certain frequencies may be lower than that determined at the corresponding contralateral angles. For each sound frequency tested, there was an angle (the acoustic axis) within the ipsilateral frontal hemisphere from which the delivered sound reached a maximal pressure level at the tympanic membrane. However, sound delivered from the acoustic axis did not always generate a maximal pressure transformation. The isopressure contours determined within 2-5 dB of the maximal pressure were circumscribed, and their contained angular areas were found to decrease with increasing sound frequency. The 2 dB maximal pressure area may appear at more than one angular area for some test frequencies. Removal of the ipsilateral pinna or modification of pinna posture expanded isopressure contours irregularly and split the 2 dB maximal pressure area into several parts.

Cytoarchitecture and sound activated responses in the auditory cortex of the big brown bat, Eptesicus fuscus

Under free field and closed-system stimulation conditions, we studied the frequency threshold curves, auditory spatial sensitivity and binaurality of neurons in the primary auditory cortex (AC) of the big brown bat, Eptesicus fuscus. All 298 recorded AC neurons discharged phasically. They were recorded at depths less than 1,000 microns with response latencies of 7-25 ms, best frequencies (BFs) of 28-97 kHz and minimum thresholds (MTs) of 8-90 dB SPL. They received excitatory inputs from the contralateral ear and either excitatory (EE) or inhibitory (EI) inputs from the ipsilateral ear. These cortical neurons were tonotopically organized along the anteroposterior axis of the AC. High best frequency neurons were located anteriorly and low best frequency neurons posteriorly. They were most sensitive to sounds delivered from a restricted region of the contralateral frontal auditory space (0 degree-50 degrees in azimuth and 2 degrees up, 15 degrees down in elevation). Frontal auditory space representation appears to be systematically arranged according to the tonotopic axis such that the lateral space is represented posteriorly and the middle space anteriorly. Cortical neurons sequentially isolated from an orthogonally penetrated electrode had similar frequency threshold curves, BFs, MTs, points of maximal auditory spatial sensitivity and binaurality. The EE and EI columns are organized concentrically such that the small number of centrally located EE columns were surrounded by an overwhelming number of EI columns. Using Nissl and Golgi stains as well as c-fos immunocytochemistry, we studied the cytoarchitecture, cell types and sound elicited Fos-like immunoreactivity in the primary AC of this bat species. The primary AC of this bat species can be described into molecular (137 microns), external granular (55 microns), external pyramidal (95 microns), internal granular (102 microns), internal pyramidal (191 microns) and multiform (120 microns) layers. The main type of cells distributed among these six layers are the small, medium and large pyramidal cells. Others include the stellate, horizontal, granular, fusiform, basket, and Martinotii cells. When stimulated with 30 kHz and 79 dB SPL sounds under natural conditions, bilaterally and symmetrically distributed Fos-like immunoreactive neurons were observed in about 20% of neurons in each AC. When stimulated under monaurally plugged conditions, 39-48% more of Fos-like immunoreactive neurons were observed in the ipsilateral AC. This finding supports the fact that the primary AC receives auditory inputs mainly from the contralateral ear.

Binaural and frequency representation in the primary auditory cortex of the big brown bat, Eptesicus fuscus

This study examines the binaural and frequency representation in the primary auditory cortex (AC) of the big brown bat, Eptesicus fuscus, by using an ear-phone stimulation system. All 306 cortical neurons studied were excited by contralateral sound stimulation but they were either excited, inhibited or not affected by ipsilateral sound stimulation. These cortical neurons were columnarly organized according to their binaural and frequency-tuning properties. The excitation-excitation columns which occupy about 15% of the AC are mainly aggregated within an oval-shaped area of the central AC. The excitation-inhibition neurons and binaural neurons with mixed properties are distributed in the remaining 85% of the surrounding primary AC. Although the best frequency (BF) of these neurons shows a tendency to decrease from high to low along the anteroposterior axis of the primary AC, systematic variation in BF is not always consistent across the entire mapping area. In particular, BFs of cortical neurons isolated in the anterior AC vary quite unsystematically such that neurons with similar BFs are aggregated in isolated patches. Isofrequency and binaural columns are segregated into bands that intersect each other.

Corticofugal control of central auditory sensitivity in the big brown bat, Eptesicus fuscus

Using bats as a model auditory system, we studied corticofugal control of auditory sensitivity of neurons in the inferior colliculus. We demonstrate for the first time that the corticocollicular pathway continuously regulates acoustic signal processing in the inferior colliculus by increasing the threshold, reducing the auditory spatial response area, and sharpening the frequency tuning curve of recorded inferior collicular neurons. Regulation of auditory sensitivity of recorded inferior collicular neurons was observed when the corticocollicular pathway was activated by electrical stimulation in the auditory cortex. The effect of this corticofugal regulation of auditory sensitivity in inferior collicular neurons can also be produced by ionophoretical application of GABA to the collicular recording site. This regulation of ascending acoustic information by commands originating from higher brain centers may provide the bat with a mechanism to actively control acoustic signal processing and thus optimize acoustic signal analysis.

Sound pressure transformation at the pinna of Mus domesticus

Sound pressure transformation properties at the pinna of laboratory mice Mus domesticus were studied by measuring the sound pressure level of a continuous tone at a series of frequencies at the tympanic membrane as a function of the position of a sound source under free-field stimulation conditions. The spectral transformation, the interaural spectral difference, the isopressure contours and the interaural pressure difference contours were plotted. Sound pressure transformation functions showed some prominent spectral notches throughout the frequency range tested (10-80 kHz). However, the notch frequency did not appear to be systematically related to sound direction. The study of interaural pressure difference demonstrated that, when delivered from some angles within the ipsilateral frontal hemisphere, the sound pressure at the tympanic membrane of certain frequencies may be lower than that determined at the corresponding contralateral angles. For each sound frequency tested, there was an angle (the acoustic axis) within the ipsilateral frontal hemisphere from which the delivered sound reached a maximal pressure level at the tympanic membrane. However, the acoustic axis often changed to a new angle after removal of the ipsilateral pinna. In addition, sound delivered from the acoustic axis did not always generate a maximal pressure transformation. The isopressure contours determined within 2-5 dB of the maximal pressure were circumscribed, and their contained angular areas were found to decrease with increasing sound frequency. The 2 dB maximal pressure area may appear at more than one angular area for some test frequencies. Removal of the ipsilateral pinna or modification of pinna posture expanded isopressure contours irregularly and split the 2 dB maximal pressure area into several parts. The sound pressure difference determined between the angles of maximal and minimal sound pressure (the maximal directionality) increased with sound frequency regardless of pinna posture. Acoustic gain of the pinna at the acoustic axis reached 6-12 dB, depending upon sound frequency. However, the pinna gain was not always maximal at the acoustic axis for a given frequency.

Pulse repetition rate increases the minimum threshold and latency of auditory neurons

The effect of pulse repetition rate on auditory sensitivity of the big brown bat, Eptesicus fuscus, was studied by determining the minimum threshold, response latency and recovery cycle of inferior collicular neurons at different repetition rates under free field stimulation conditions. In general, collicular neurons shortened the response latency and increased the number of impulses monotonically or non-monotonically with stimulus intensity. They recovered at least 50% when the interpulse interval was 10-57 ms. In addition, they increased the minimum threshold, lengthened the response latency, and reduced the number of impulses discharged to each pulse with increasing repetition rate. The increase in minimum threshold with repetition rate is partly because the neuron can not recover from previous stimulation when the interpulse interval is shortened. This increase reduces a neuron's response sensitivity and thus diminishes its number of impulses to each presented pulse. This increase also reduces the effectiveness of a given stimulus intensity which contributes to the lengthening of the neuron's response latency. Data obtained from single neuron recordings are used to highlight these observations. Implications of present findings regarding the bat's echolocation are also discussed.

[Thymus pathological changes in perinatal babies and children]

The most outstanding pathological changes of perinatal babies and children, based on the review of the autopsy files in the 1st Affiliated Hospital of West China University of Medical Sciences, are lymphocytic depletion, and reticuloepithelial cell swelling and/or fusiform malformation in the cortex, while in the medulla apoptosis is more prominent. We suppose that these alterations are due to immaturity of cortical thymocytes, and in the diseased condition, they are easily affected by extraordinary factors, especially the influence of corticosterone inducing acute severe necrosis, so the number of lymphocytes are obviously diminished. But, in the medulla, as intact mature lymphocytes exist, physiological phenomenon such as apoptosis is rather prominent in it. While in the medulla, Hassall's corpuscles have various characteristic changes, such as cornification, calcification, fusion, cystic change and disintegration. Besides, we observed a new alteration in the thymus defined as vacuolization. All the above pathological changes reached the peak in the 28- day group; there after, they might become either worse or better according to the condition of the disease and growth of the body. However, these are still problems to be further studied separately.