Intratumor microbiome derived glycolysis-lactate signatures depicts immune heterogeneity in lung adenocarcinoma by integration of microbiomic, transcriptomic, proteomic and single-cell data

Introduction

Microbiome plays roles in lung adenocarcinoma (LUAD) development and anti-tumor treatment efficacy. Aberrant glycolysis in tumor might promote lactate production that alter tumor microenvironment, affecting microbiome, cancer cells and immune cells. We aimed to construct intratumor microbiome score to predict prognosis of LUAD patients and thoroughly investigate glycolysis and lactate signature's association with LUAD immune cell infiltration.

Methods

The Cancer Genome Atlas-LUAD (TCGA-LUAD) microbiome data was downloaded from cBioPortal and analyzed to examine its association with overall survival to create a prognostic scoring model. Gene Set Enrichment Analysis (GSEA) was used to find each group's major mechanisms involved. Our study then investigated the glycolysis and lactate pattern in LUAD patients based on 19 genes, which were correlated with the tumor microenvironment (TME) phenotypes and immunotherapy outcomes. We developed a glycolysis-lactate risk score and signature to accurately predict TME phenotypes, prognosis, and response to immunotherapy.

Results

Using the univariate Cox regression analysis, the abundance of 38 genera were identified with prognostic values and a lung-resident microbial score (LMS) was then developed from the TCGA-LUAD-microbiome dataset. Glycolysis hallmark pathway was significantly enriched in high-LMS group and three distinct glycolysis-lactate patterns were generated. Patients in Cluster1 exhibited unfavorable outcomes and might be insensitive to immunotherapy. Glycolysis-lactate score was constructed for predicting prognosis with high accuracy and validated in external cohorts. Gene signature was developed and this signature was elevated in epithelial cells especially in tumor mass on single-cell level. Finally, we found that the glycolysis-lactate signature levels were consistent with the malignancy of histological subtypes.

Discussion

Our study demonstrated that an 18-microbe prognostic score and a 19-gene glycolysis-lactate signature for predicting prognosis of LUAD patients. Our LMS, glycolysis-lactate score and glycolysis-lactate signature have potential roles in precision therapy of LUAD patients.

Effects of SVEP1 on Lung Squamous Cell Carcinoma and its Association with Tumor Mutation Burden, Prognosis, and Immune Regulation

BACKGROUND

The mutated genes in lung squamous cell carcinoma were investigated for their possible association with tumor mutation burden, microsatellite instability, and cancer prognosis.

OBJECTIVE

Our study aims to evaluate the value of the candidate genes as a potential biomarker of lung squamous cell carcinoma and pan-cancer analysis.

METHODS

The landscape of the tumor microenvironment and infiltrating lymphocytes in lung squamous cell carcinoma was calculated using ESTIMATE and CIBERSORT algorithm. Weighed gene co-expression network analysis was used to screen key modules related to immune cell infiltration. Somatic mutations were found by data analysis from the TCGA and ICGC databases. Mann-Whitney U test was used to evaluate the tumor mutation burden difference between patients with mutant and wild-type SVEP1 genes. The Kaplan-Meier method was used to examine the prognosis of the patients with mutations. The effects of SVEP1 expression on tumor mutation burden and immunity in different cancers were determined by pan-cancer analysis.

RESULTS

SVEP1 mutation was found to be associated with a higher tumor mutation burden and prognosis. SVEP1 mutation might be involved in the possible biological process of the anti-tumor immune response. SVEP1 is related to different degrees of immune infiltration in cancer. Moreover, the miRNA-SVEP1 targeting network was used to illuminate the possible mechanisms.

CONCLUSION

SVEP1 mutation and its mRNA expression are related to tumor mutation burden and cancer immunity in lung squamous cell carcinoma. Our findings reveal the underlying mechanisms, indicating that SVEP1 may be a prognostic marker of lung squamous cell carcinoma.

Cell Trajectory-Related Genes of Lung Adenocarcinoma Predict Tumor Immune Microenvironment and Prognosis of Patients

Background

Lung adenocarcinoma (LUAD) is the most common subtype of lung cancer which typically exhibits a diverse progression trajectory. Our study sought to explore the cell differentiation trajectory of LUAD and its clinical relevance.

Methods

Utilizing a single-cell RNA-sequencing dataset (GSE117570), we identified LUAD cells of distinct differential status along with differentiation-related genes (DRGs). DRGs were applied to the analysis of bulk-tissue RNA-sequencing dataset (GSE72094) to classify tumors into different subtypes, whose clinical relevance was further analyzed. DRGs were also applied to gene co-expression network analysis (WGCNA) using another bulk-tissue RNA-sequencing dataset (TCGA-LUAD). Genes from modules that demonstrated a significant correlation with clinical traits and were differentially expressed between normal tissue and tumors were identified. Among these, genes with significant prognostic relevance were used for the development of a prognostic nomogram, which was tested on TCGA-LUAD dataset and validated in GSE72094. Finally, CCK-8, EdU, cell apoptosis, cell colony formation, and Transwell assays were used to verify the functions of the identified genes.

Results

Four clusters of cells with distinct differentiation status were characterized, whose DRGs were predominantly correlated with pathways of immune regulation. Based on DRGs, tumors could be clustered into four subtypes associated with distinct immune microenvironment and clinical outcomes. DRGs were categorized into four modules. A total of nine DRGs (SFTPB, WFDC2, HLA-DPA1, TIMP1, MS4A7, HLA-DQA1, VCAN, KRT8, and FABP5) with most significant survival-predicting power were integrated to develop a prognostic model, which outperformed the traditional parameters in predicting clinical outcomes. Finally, we verified that knockdown of WFDC2 inhibited proliferation, migration, and invasion but promoted the apoptosis of A549 cells in vitro.

Conclusion

The cellular composition and cellular differentiation status of tumor mass can predict the clinical outcomes of LUAD patients. It also plays an important role in shaping the tumor immune microenvironment.

Endogenous tryptophan metabolite 5-Methoxytryptophan inhibits pulmonary fibrosis by downregulating the TGF-β/SMAD3 and PI3K/AKT signaling pathway

Pulmonary fibrosis is the end stage of many interstitial lung diseases, characterized by the deposition of excess extracellular matrix (ECM), destruction of normal alveolar structure, and resulting in the obstruction of gas exchange and respiratory failure. The idiopathic pulmonary fibrosis (IPF) is the most common form of pulmonary fibrosis with little effective therapies. 5-Methoxytryptophan (5-MTP) is a newly found tryptophan metabolite. Previous studies suggested that 5-MTP has the effects of anti-inflammatory, anti-tumorigenesis, vascular protection and anti-fibrosis in renal disease. Whether 5-MTP has therapeutic effect on pulmonary fibrosis is not clear. In our study, we used TGF-β1 to stimulate human lung fibroblasts (HLFs) and bleomycin (BLM) induced pulmonary fibrosis model to investigate the effect of 5-MTP on pulmonary fibrosis. Our study demonstrated that 5-MTP could improve the lung function and attenuate the destruction of alveolar structure in BLM-induced pulmonary fibrosis mice. Furthermore, 5-MTP significantly decreased accumulation of myofibroblasts and the deposition of ECM by inhibiting the differentiation of fibroblasts to myofibroblasts and suppressing the protein expression of the ECM both in vivo and in vitro. Our results also revealed 5-MTP could inhibit the proliferation and migration of the fibroblasts in vitro, which played an important role in the progressive pulmonary fibrosis. To further investigate the mechanism of the anti-fibrosis of 5-MTP, several canonical and noncanonical signaling pathways were examined. Our results revealed that 5-MTP could inhibit the pulmonary fibrosis through downregulating the phosphorylation of TGF-β/SMAD3, PI3K/AKT signaling pathways. Together, our study indicated that 5-MTP promises to be therapeutic agent of pulmonary fibrosis.

Genome-wide copy number variation analysis identified ANO1 as a novel oncogene and prognostic biomarker in esophageal squamous cell cancer

Copy number variations (CNVs) represent one of the most common genomic alterations. This study aimed to evaluate the roles of genes within highly aberrant genome regions in the prognosis of esophageal squamous cell cancer (ESCC). Exome sequencing data from 81 paired ESCC tissues were used to screen aberrant genomic regions. The associations between CNVs and gene expression were evaluated using gene expression data from the same individuals. Then, an RNA expression array profile from 119 ESCC samples was adopted for differential gene expression and prognostic analyses. Two independent ESCC cohorts with 315 subjects were further recruited to validate the prognostic value using immunohistochemistry tests. Finally, we explored the potential mechanism of our identified novel oncogene in ESCC. In total, 2003 genes with CNVs were observed, of which 76 genes showed recurrent CNVs in more than three samples. Among them, 32 genes were aberrantly expressed in ESCC tumor tissues and statistically correlated with CNVs. Strikingly, 4 (CTTN, SHANK2, INPPL1 and ANO1) of the 32 genes were significantly associated with the prognosis of ESCC patients. Patients with a positive expression of ANO1 had a poorer prognosis than ANO1 negative patients (overall survival rate: 42.91% versus 26.22% for ANO1-/+ samples, P < 0.001). Functionally, ANO1 promoted ESCC cell proliferation, migration and invasion by activating transforming growth factor-β pathway. Knockdown of ANO1 significantly inhibited tumor progression in vitro and in vivo. In conclusion, ANO1 is a novel oncogene in ESCC and may serve as a prognostic biomarker for ESCC.

Postoperative diffused alveolar hemorrhage complicated by pneumonia after lung cancer surgery in a patient with liver cirrhosis: a case report and review of literatures

Postoperative pulmonary complications remain a challenge after pulmonary surgery in patients with severe cirrhosis in spite of advances in perioperative management. Diffused alveolar hemorrhage (DAH) is a pernicious clinical syndrome that is often primarily assumed to be atypical pneumonia. We report a case of a 54-year-old man presented with shortness of breath on the first post-operation day, who was successfully treated by left superior segmentectomy and right superior wedge resection. Imaging studies showed patchy infiltrates scattered throughout both lungs. Klebsiella pneumoniae and Candida albicans were found in the sputum culture. Management strategy was designed to provide adequate respiratory support, treat underlying infections and control inflammation. Non-invasive ventilator assisted ventilation was performed. We proposed that cirrhosis-induced DAH should be considered in the differential diagnosis of early pulmonary complications after pulmonary surgery. Early diagnosis and proper but not aggressive treatment protocol are crucial for recovery.

Systematic analysis of genetic variants in cancer-testis genes identified two novel lung cancer susceptibility loci in Chinese population

Cancer-testis (CT) genes played important roles in the progression of malignant tumors and were recognized as promising therapeutic targets. However, the roles of genetic variants in CT genes in lung cancer susceptibility have not been well depicted. This study aimed to evaluate the associations between genetic variants in CT genes and lung cancer risk in Chinese population. A total of 22,556 qualified SNPs from 268 lung cancer associated CT genes were initially evaluated based on our previous lung cancer GWAS (Genome-wide association studies) with 2,331 cases and 3,077 controls. As a result, 17 candidate SNPs were further genotyped in 1,056 cases and 1,053 controls using Sequenom platform. Two variants (rs6941653, OPRM1, T > C, screening: OR = 1.24, 95%CI: 1.12-1.38, P = 2.40×10^-5; validation: OR = 1.18, 95%CI: 1.01-1.37, P = 0.039 and rs402969, NLRP8, C > T, screening: OR = 1.15, 95%CI: 1.04-1.26, P = 0.006; validation: OR = 1.16, 95%CI: 1.02-1.33, P = 0.028) were identified as novel lung cancer susceptibility variants. Stratification analysis indicated that the effect of rs6941653 was stronger in lung squamous cell carcinoma (OR = 1.36) than that in lung adenocarcinoma (OR = 1.15, I² = 77%, P = 0.04). Finally, functional annotations, differential gene expression analysis, pathway and gene ontology analyses were performed to suggest the potential functions of our identified variants and genes. In conclusion, this study identified two novel lung cancer risk variants in Chinese population and provided deeper insight into the roles of CT genes in lung tumorigenesis.

Systematic cancer-testis gene expression analysis identified CDCA5 as a potential therapeutic target in esophageal squamous cell carcinoma

Background

Esophageal squamous cell carcinoma (ESCC) is one of the most lethal malignancies with poor prognosis. Cancer-testis genes (CTGs) have been vigorously pursued as targets for cancer immunotherapy, but the expressive patterns and functional roles of CTGs remain unclear in ESCC.

Methods

A systematic screening strategy was adopted to screen CTGs in ESCC by integrating multiple public databases and RNA expression microarray data from 119 ESCC subjects. For the newly identified ESCC prognosis-associated CTGs, an independent cohort of 118 patients with ESCC was recruited to validate the relationship via immunohistochemistry. Furthermore, functional assays were performed to determine the underlying mechanisms.

Findings

21 genes were recognized as CTGs, in particular, CDCA5 was aberrantly upregulated in ESCC tissues and significantly associated with poor prognosis (HR = 1.85, 95%CI: 1.14–3.01, P = .013). Immunohistochemical staining confirmed that positive CDCA5 expression was associated with advanced TNM staging and a shorter overall survival rate (45.59% vs 28.00% for CDCA5−/+ subjects, P = 1.86 × 10⁻³). H3K27 acetylation in CDCA5 promoter might lead to the activation of CDCA5 during ESCC tumorigenesis. Functionally, in vitro assay of gain- and loss-of-function of CDCA5 suggested that CDCA5 could promote ESCC cells proliferation, invasion, migration, apoptosis resistance and reduce chemosensitivity to cisplatin. Moreover, in vivo assay showed that silenced CDCA5 could inhibit tumor growth. Mechanistically, CDCA5 knockdown led to an arrest in G2/M phase and changes in the expression of factors that played fundamental roles in the cell cycle pathway.

Interpretation

CDCA5 contributed to ESCC progression and might serve as an attractive target for ESCC immunotherapy.

Fund

This work was supported by the Natural Science Foundation of Jiangsu Province (No. BK20181083 and BK20181496), Jiangsu Top Expert Program in Six Professions (No. WSW-003 and WSW-007), Major Program of Science and Technology Foundation of Jiangsu Province (No. BE2016790 and BE2018746), Jiangsu Medical Young Talent Project (No. QNRC2016566), the Program of Jiangsu Medical Innovation Team (No. CXTDA2017006), Postgraduate Research & Practice Innovation Program of Jiangsu Province (KYCX18_1487) and Jiangsu Province 333 Talents Project (No. BRA2017545).

Factors in Sustained Compliance to a Symptom-Reporting Mobile Application: Implications for Clinical Implementation

Background: The Internet-based Computerized Patient Assessment System (iComPAsS), a remote pain- and symptom-reporting application was developed to optimize pain monitoring and management. This subanalysis sought to examine factors influencing compliance, to gauge the sustainability of its effects and to guide further development and implementation as part of usual care. Aim: This analysis sought to examine factors influencing compliance, to gauge the sustainability of its effects and to guide further development and implementation as part of usual care. Methods: Patients ≥ 18 years old, with cancer and moderate-severe pain were randomized to standard pain management with pain diary or iComPAsS. Pain and symptom severity (using Edmonton Symptom Assessment Scale) and compliance (to iComPAsS or diary) were evaluated at week 0, 3, 6, 12 and 20. The Treatment Self-regulation Questionnaire (TSRQ), used to assess patient motivation, was administered at week 0, 6, 12 and 20. Pain levels and compliance were compared between the groups using the Student t-test. The Pearson correlation coefficient was used to examine the relationship between compliance and pain control, perceived competence in pain self-care, and relative autonomy index. Results: Out of 100 patients enrolled, 76 were included in the analysis (control; 37; iComPAsS, 39). Baseline pain levels and TSRQ characteristics were similar between the groups. Initial compliance and pain control at week 3 were significantly higher in the iComPAsS group. For the iCompAsS group, compliance directly correlated with uncontrolled pain and intrinsic motivation, and was more sustained compared with the control group. Conclusion: The iComPAsS elicited rapid uptake and sustained compliance through intrinsic motivation. When adopting the iComPAsS for clinical use, patient baseline motivation levels may be assessed using the TSRQ, and depressive symptoms and other barriers to engagement must be identified.

ER Stress via CHOP Pathway is Involved in FK506-Induced Apoptosis in Rat Fibroblasts

Background/Aims: Hypertrophic scars (HS) formation results from reduced apoptosis and increased proliferation of fibroblasts. Therefore, apoptosis of fibroblasts is a key target for the development of novel therapeutic strategies for HS. Previous reports demonstrated that FK506 could attenuate scar formation in vivo and FK506 could also induce endoplasmic reticulum stress (ER stress). However, the effects of FK506 on ER stress-mediated apoptosis in fibroblasts remain unclear. Methods: Rat skin fibroblasts were used in the study. Cell viability was examined using cell counting Kit-8. Apoptosis was detected by Annexin V/Propidium Iodide Double Staining. Gene silencing was performed using Small Interfering RNAs (siRNAs) or via lentiviral infection. The expression of apoptosis-related proteins was determined via Western blot. Interaction between proteins was explored by co-immunoprecipitation. Results: FK506 significantly reduced cell viability and induced apoptosis in fibroblasts. Interestingly, ER stress was also activated after FK506 treatment. We further demonstrated that FK506-induced apoptosis was mediated by ER stress via activating CHOP, evidenced by decreased apoptosis after inhibition of ER stress using TUDCA or silencing expression of CHOP. Furthermore, Co-immunoprecipitation results indicated that treatment of FK506 induced disassociation of FKBP12.6 from RyR2 and its translocation from ER membrane to cytosol, consequently promoting ER stress-mediated apoptosis. Conclusion: FK506-induced fibroblasts apoptosis was mediated by ER stress via CHOP signaling pathway.

Taurine Reduced Epidural Fibrosis in Rat Models after Laminectomy via Downregulating EGR1

BACKGROUND/AIMS

Epidural fibrosis, a common complication after laminectomy, has been demonstrated to be closely associated with poor surgical outcomes. Previous studies showed that taurine had remarkable anti-fibrotic effects on lung and liver fibrosis. We performed this study to investigate the effects of taurine in rat models of epidural fibrosis after laminectomy and to explore the potential molecular mechanism.

METHODS

Laminectomy was performed on each rat to establish epidural fibrosis model. After taurine treatment, Masson's trichrome and immunohistochemistry staining were used to examine epidural fibrosis. Cell viability was determined using the Cell Counting Kit-8 assay. Annexin V/Propidium Iodide double staining was performed to detect fibroblasts apoptosis. Microarray was adopted to identify significantly changed mRNAs. mRNA expression was measured by qRT-PCR. Lentivirus infection was performed to establish stable knockdown and overexpression cell lines. The expression of fibrosis-related proteins was determined via Western blot.

RESULTS

Taurine treatment markedly reduced laminectomy-induced epidural fibrosis in rat models. However, this effect of taurine was independent on TGF-β/Smad pathway, evidenced by no change in the expression of TGF-β and its receptors. Besides, taurine had almost no effect on cell apoptosis. Interestingly, taurine treatment significantly decreased expression of EGR1 (Early growth response protein 1), an enhancer of fibrosis, both in vivo and in vitro. Furthermore, overexpression of EGR1 increased activation of fibroblasts, while EGR1 knockdown achieved an opposite effect, indicating that EGR1 plays a key role in the inhibitory effect of taurine on TGF-β-induced fibrosis.

CONCLUSIONS

Reduced epidural fibrosis in vivo and decreased activation of fibroblasts in vitro after taurine treatment was mediated by EGR1. Taurine promises to be a potential prevention for epidural fibrosis after laminectomy.

Tacrolimus reduces scar formation and promotes sciatic nerve regeneration

A sciatic nerve transection and repair model was established in Sprague-Dawley rats by transecting the tendon of obturator internus muscle in the greater sciatic foramen and suturing with nylon sutures. The models were treated with tacrolimus gavage (4 mg/kg per day) for 0, 2, 4 and 6 weeks. Specimens were harvested at 6 weeks of intragastric administration. Masson staining revealed that the collagen fiber content and scar area in the nerve anastomosis of the sciatic nerve injury rats were significantly reduced after tacrolimus administration. Hematoxylin-eosin staining showed that tacrolimus significantly increased myelinated nerve fiber density, average axon diameter and myelin sheath thickness. Intragastric administration of tacrolimus also led to a significant increase in the recovery rate of gastrocnemius muscle wet weight and the sciatic functional index after sciatic nerve injury. The above indices were most significantly improved at 6 weeks after of tacrolimus gavage. The myelinated nerve fiber density in the nerve anastomosis and the sciatic nerve functions had a significant negative correlation with the scar area, as detected by Spearman’s rank correlation analysis. These findings indicate that tacrolimus can promote peripheral nerve regeneration and accelerate the recovery of neurological function through the reduction of scar formation.

Rapid identification of spinal ventral and dorsal roots using a quartz crystal microbalance

The fast and accurate identification of nerve tracts is critical for successful nerve anastomosis. Taking advantage of differences in acetylcholinesterase content between the spinal ventral and dorsal roots, we developed a novel quartz crystal microbalance method to distinguish between these nerves based on acetylcholinesterase antibody reactivity. The acetylcholinesterase antibody was immobilized on the electrode surface of a quartz crystal microbalance and reacted with the acetylcholinesterase in sample solution. The formed antigen and antibody complexes added to the mass of the electrode inducing a change in frequency of the electrode. The spinal ventral and dorsal roots were distinguished by the change in frequency. The ventral and dorsal roots were cut into 1 to 2-mm long segments and then soaked in 250 μL PBS. Acetylcholinesterase antibody was immobilized on the quartz crystal microbalance gold electrode surface. The results revealed that in 10 minutes, both spinal ventral and dorsal roots induced a frequency change; however, the frequency change induced by the ventral roots was notably higher than that induced by the dorsal roots. No change was induced by bovine serum albumin or PBS. These results clearly demonstrate that a quartz crystal microbalance sensor can be used as a rapid, highly sensitive and accurate detection tool for the quick identification of spinal nerve roots intraoperatively.

Potential risk of mitomycin C at high concentrations on peripheral nerve structure

Although the local application of mitomycin C may prevent epidural adhesion after laminectomy, mitomycin C can induce neurotoxicity in optic and acoustic nerves at high concentrations. To determine the safe concentration range for mitomycin C, cotton pads soaked with mitomycin C at different concentrations (0.1, 0.3, 0.5, and 0.7 mg/mL) were immediately applied for 5 minutes to the operation area of rats that had undergone laminectomy at L₁. Rat sciatic nerves, instead of dorsal nerves, were used in this study. The results showed that mitomycin C at 0.1-0.5 mg/mL did not damage the structure and function of the sciatic nerve, while at 0.7 mg/mL, mitomycin C significantly reduced the thickness of the sciatic nerve myelin sheath compared with lower concentrations, though no functional change was found. These experimental findings indicate that the local application of mitomycin C at low concentrations is safe to prevent scar adhesion following laminectomy, but that mitomycin C at high concentrations (> 0.7 mg/mL) has potential safety risks to peripheral nerve structures.

Effect of FK506 in reducing scar formation by inducing fibroblast apoptosis after sciatic nerve injury in rats

We previously demonstrated that FK506, a generally applied immunosuppressant in organ transplantation, could promote peripheral nerve regeneration through reducing scar formation. However, little is known about how FK506 reduces scar formation. Herein we investigated the influence of FK506 on fibroblast proliferation and its correlation with scar formation after sciatic nerve injury in rats, and further explored the effect of FK506 on fibroblast proliferation and apoptosis in vitro. Masson staining and immunohistochemistry revealed that scar area and fibroblast number in the nerve anastomosis of sciatic nerve-injured rats were significantly reduced after FK506 administration. The scar area had a significant positive correlation with the fibroblast number, as detected by linear correlation analysis. CCK-8 assay and flow cytometry indicated that FK506 also inhibited proliferation and induced apoptosis of fibroblasts in vitro. It was primarily phosphorylation of JNK and ERK that were activated during the apoptosis of fibroblast. Pretreatment of cells with JNK inhibitor, SP600125, or ERK inhibitor, PD98059, could inhibit FK506-induced fibroblast apoptosis, respectively. Moreover, simultaneous application of both inhibitors had additive roles in cell protection from apoptosis. These results suggest that FK506-induced fibroblast apoptosis contributes to the suppression of fibroblast proliferation and then results in the reduction of scar formation in sciatic nerve-injured rat, and that JNK and ERK are involved in FK506-induced fibroblast apoptosis.

Epithelial stem/progenitor cells in lung postnatal growth, maintenance, and repair

The adult lung consists of a trachea leading into a system of branched airways ending in millions of alveolar sacs. It contains many different epithelial cell types arranged in precise patterns along the proximodistal axis. Each region of the lung has the capacity to repair through the proliferation of different epithelial cell types. However, the precise identity of the cells mediating repair is not fully resolved. To address this problem, we are using genetic lineage-labeling techniques in the mouse. The tools we have made will also be useful for understanding how progenitor cell behavior is regulated under normal and pathological conditions.

Unusual persistence in healthy volunteers and ill patients of hyperimmune immunoglobulin directed against multiple Pseudomonas O-chain and Klebsiella serotypes after intravenous infusion

Persistence of intravenous (i.v.) hyperimmune immunoglobulin (100 mg/kg) directed against clinically predominant serotypes of Pseudomonas and Klebsiella in ill, febrile patients was compared to healthy volunteers to determine if ill patients have a decreased Ig half-life resulting in an increased immunoglobulin requirement. Type-specific antibodies were measured by ELISA for 83 days in eight healthy volunteers and for 35 days in eight ill patients with surgical complications or hematologic malignancy. Mean values and fold rises of antibody concentrations for the two groups were above preinfusion values at 35 days. The antibody fold rises in patients and in healthy volunteers were similar. Type-specific antibody levels in some patients increased after illness coincident with elevation of total immunoglobulins. We conclude that the duration of potentially therapeutic levels of infused type-specific hyperimmune immunoglobulin may persist for a longer period of time than what has been measured for total immunoglobulin. While the mechanism of this persistence remains to be characterized, the possibility of type-specific antibody synthesis induced by immunoglobulin administration must be considered.

Does bowel preparation improve the quality of abdominal gallium scintigraphy?

Physiological accumulation of gallium in the intestine is a major weakness of gallium scintigraphy in evaluating the abdomen. In this study, we used two different cathartics to evaluate the efficacy of bowel cleansing in improving the quality of abdominal gallium imaging. One hundred and fifty patients underwent gallium scintigraphy and were randomly divided into three groups. Group A received no bowel preparation, Group B received 30 ml of castor oil the night before imaging, and Group C received bisacodyl the night before imaging. Gallium activity in the intestine was rated on a three-point scale from 0 to II based on the anterior view of a delayed 48-h gallium image. Our data showed that the incidence of gallium accumulation in the small intestine was low. On the contrary, there was high prevalence of gallium activity in the colon. Forty-eight percent of Group A patients had obvious gallium activity in the colon. The percentage decreased significantly to 28% and 22% in Groups B and C, respectively. No significant difference was noted between Group B and Group C. In conclusion, our data suggest that the application of either castor oil or bisacodyl significantly improves the quality of 48-h abdominal gallium scintigraphy. There were no significant differences in the efficacy of bowel cleansing on gallium activity between these two laxatives.

Modulation of excitatory synaptic transmission by low concentrations of glutamate in cultured rat hippocampal neurons

1. The effects of low micromolar concentrations of glutamate on fast excitatory synaptic responses were studied in microcultures of postnatal rat hippocampal neurons using whole-cell patch clamp recordings. 2. Glutamate depressed the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor component of excitatory autaptic currents (EACs) with an EC50 of 3.8 microM. 3. Both pre- and postsynaptic effects contributed to the depression of AMPA receptor-mediated EACs. Cyclothiazide and wheatgerm agglutinin, agents which inhibit AMPA receptor desensitization, partially reversed the depression produced by glutamate, as did pertussis toxin, an agent that blocks presynaptic inhibition mediated by metabotropic glutamate receptors. 4. In neurons in which both the AMPA and N-methyl-D-aspartate (NMDA) receptor components of EACs were examined, low concentrations of glutamate depressed the NMDA component of EACs to a greater extent. The EC50 for inhibiting the NMDA component was 1.3 microM. 5. Calcium-dependent desensitization of postsynaptic NMDA receptors contributed to the depression of NMDA receptor-mediated synaptic responses. Both depolarization of postsynaptic neurons to +70 mV to decrease Ca2+ influx via NMDA channels and inclusion of high concentrations of a calcium chelator in recording pipettes decreased the depression of NMDA receptor-mediated EACs. 6. Threo-3-hydroxy-aspartate (THA), an inhibitor of glutamate transport, depressed EACs by about 10% and increased the degree of depression produced by 2.5 microM glutamate, suggesting that glutamate transport in microcultures helps to control ambient glutamate levels. 7. Because the normal extracellular concentration of glutamate is about 1 microM, these results suggest that the ambient glutamate level is an important determinant of synaptic efficacy. Relatively small changes in extracellular glutamate can alter fast excitatory synaptic transmission by both presynaptic and postsynaptic mechanisms.

Passive and synaptic properties of hippocampal neurons grown in microcultures and in mass cultures

1. We used whole cell recordings to compare passive membrane properties and synaptic properties of postnatal rat hippocampal neurons grown for 7-15 days in either conventional mass cultures or on physically restricted microisland cultures. Despite matching microisland and mass culture cell across several variables, there were significant differences between neurons in the two groups regarding passive membrane characteristics and synaptic properties. 2. Microisland neurons displayed significantly faster charging of the membrane capacitance than mass culture counterparts matched with microisland neurons for age, somal diameter, and transmitter phenotype. When we used a two-compartment equivalent circuit model to quantify this result, microisland neurons displayed approximately half the distal capacitance of mass culture neurons. These data suggest that microisland neurons elaborate less extensive neuritic arborizations than mass culture neurons. 3. Evoked synaptic responses were enhanced on microislands compared with mass cultures. Excitatory and inhibitory autaptic currents were more frequent and displayed larger amplitudes on single-neuron microislands than in matched mass culture neurons. 4. In recordings from pairs of neurons in the two environments, we observed a significantly higher probability of obtaining a monosynaptic response on two-neuron microislands than in matched mass culture pairs (85% vs. 42%). Evoked excitatory postsynaptic currents were also significantly larger in the microisland environment, with evoked excitatory synaptic currents from two-neuron microislands exhibiting a mean amplitude 20-fold larger than mass culture monosynaptic responses. 5. The differences in evoked synaptic responses were not reflected in differences in the amplitude or frequency of spontaneous miniature excitatory postsynaptic currents (mEPSCs). Analysis of mEPSC rise times, decay times, and peak amplitudes within individual cells suggests that electrotonic filtering is not an important contributor to the variability of peak amplitudes and decay times of synaptic currents in cells of either culture environment. However, composite data across neurons in both cultures reveal a significant correlation between mEPSC rise and decay times. 6. Out results suggest that the microisland preparation may be a useful tool for exploring factors that influence synapse formation and development. Additionally, the preparation is a particularly convenient model for the study of single-neuron-mediated synaptic events.

Safety and immunogenicity of a polyvalent Escherichia coli vaccine in human volunteers

Since a limited number of O serogroups account for nearly 70% of bacteremic and meningitic Escherichia coli isolates, a polyvalent vaccine was made by conjugating a Pseudomonas aeruginosa exotoxin A carrier protein to the O polysaccharide of 12 serogroups of E. coli (O1, O2, O4, O6-O8, O12, O15, O16, O18, O25, O75). No serious reactions occurred in 88 vaccinees. Four-fold or greater increases in ELISA antibody levels over baseline were greatest (> 60% of vaccinees) for O1, O2, O6-O8 and O15; intermediate (approximately 50%) for O18 and O75, and poorest (> or = 45%) for O4, O12, O16, and O25. Responses with functionally active opsonophagocytic antibody generally paralleled ELISA antibody responses. With the availability of a safe, immunogenic E. coli vaccine, active and passive immunization strategies merit further development as adjunctive treatment for E. coli bacteremia and neonatal meningitis.

Barbiturate depression of a K+ dependent inhibitory synapse is independent of dendritic cable filtering

Technical limitations with intracellular electrophysiological methods usually restrict recording of postsynaptic potentials only from neuronal soma, a site remote from the actual synapse. The intervening dendritic cable interposed between the actual synapse and the site of recording can significantly filter the synaptic signal. Therefore, investigations of drug effect on synaptic mechanisms, based on postsynaptic recordings obtained at the soma, must be interpreted with care. The potential role of dendritic cable filtering in the atypical pentobarbital depression of a K(+)-dependent inhibitory synapse between the P to Nut cell in the posterior packet of the leech was investigated. The effective electrical geometry under the conditions of control and 0.5 mM PNB sufficient to completely abolish the postsynaptic potential were determined from analyses of the membrane charging curves assuming the lumped-soma-short-cable model. Under the control condition, the postsynaptic Nut cell exhibits dendritic dominance with rho = 2.52, normalized equivalent cable length L = 1.08, and a membrane time constant tau o = 52 ms. With phenobarbital application, changes in the geometrical parameters consistent with a decrease in the specific membrane resistance Rm are observed. Simulation of the drug induced change in the electrical geometry demonstrates that the decrease in the post synaptic potential is largely due to the decrease in the soma input resistance and an increase in the cable filter contributes little to the observed depression of the postsynaptic potential. However, the combined effect of the decrease in the input resistance and the increase in the cable filtering of synaptic current is insufficient in explaining the observed total block of the synaptic potential by PNB.(ABSTRACT TRUNCATED AT 250 WORDS)