M-BLUE protocol for coronavirus disease-19 (COVID-19) patients: interobserver variability and correlation with disease severity

AIM

To retrospectively evaluate the interobserver variability of intensive care unit (ICU) practitioners and radiologists who used the M-BLUE (modified bedside lung ultrasound in emergency) protocol to assess coronavirus disease-19 (COVID-19) patients, and to determine the correlation between total M-BLUE protocol score and three different scoring systems reflecting disease severity.

MATERIALS AND METHODS

Institutional review board approval was obtained and informed consent was not required. Ninety-six lung ultrasonography (LUS) examinations were performed using the M-BLUE protocol in 79 consecutive COVID-19 patients. Two ICU practitioners and three radiologists reviewed video clips of the LUS of eight different regions in each lung retrospectively. Each observer, who was blind to the patient information, described each clip with M-BLUE terminology and assigned a corresponding score. Interobserver variability was assessed using intraclass correlation coefficient. Spearman's correlation coefficient analysis (R-value) was used to assess the correlation between the total score of the eight video clips and disease severity.

RESULTS

For different LUS signs, fair to good agreement was obtained (ICC = 0.601, 0.339, 0.334, and 0.557 for 0-3 points respectively). The overall interobserver variability was good for both the five different readers and consensus opinions (ICC = 0.618 and 0.607, respectively). There were good correlations between total LUS score and scores from three systems reflecting disease severity (R=0.394-0.660, p<0.01).

CONCLUSION

In conclusion, interobserver agreement for different signs and total scores in LUS is good and justifies its use in patients with COVID-19. The total scores of LUS are useful to indicate disease severity.

Thyroid hormone concentrations in severely or critically ill patients with COVID-19

OBJECTIVE

COVID-19 is a new coronavirus infectious disease. We aimed to study the characteristics of thyroid hormone levels in patients with COVID-19 and to explore whether thyroid hormone predicts all-cause mortality of severely or critically ill patients.

METHODS

The clinical data of 100 patients with COVID-19, who were admitted to Wuhan Tongji Hospital from February 8 to March 8, 2020, were analyzed in this retrospective study. The patients were followed up for 6-41 days. Patients were grouped into non-severe illness and severe or critical illness, which included survivors and non-survivors. Multivariate Cox proportional hazards analysis was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause mortality in association with continuous and the lower two quartiles of thyroid hormone concentrations in severely or critically ill patients.

RESULTS

The means of free T3 (FT3) were 4.40, 3.73 and 2.76 pmol/L in non-severely ill patients, survivors and non-survivors, respectively. The lower (versus upper) two quartiles of FT3 was associated with all-cause mortality HR (95% CI) of 9.23 (2.01, 42.28). The HR (95% CI) for all-cause mortality in association with continuous FT3 concentration was 0.41 (0.21, 0.81). In the multivariate-adjusted models, free T4 (FT4), TSH and FT3/FT4 were not significantly related to all-cause mortality. Patients with FT3 less than 3.10 pmol/L had increased all-cause mortality.

CONCLUSION

FT3 concentration was significantly lower in patients with severe COVID-19 than in non-severely ill patients. Reduced FT3 independently predicted all-cause mortality of patients with severe COVID-19.

Long-term study of heavy metal pollution in the northern Hangzhou Bay of China: temporal and spatial distribution, contamination evaluation, and potential ecological risk

Coastal ecosystem is vulnerable to heavy metal contamination. The northern Hangzhou Bay is under intensifying impact of anthropogenic activities. To reveal the heavy metal pollution status in the coastal environment of the Hangzhou Bay, a long-term investigation into the heavy metal contamination during 2011 to 2016 was initiated. Seawater and sediment samples of 25 locations depending on the sewage outlet locations in the northern Hangzhou Bay were collected to analyze the concentrations and temporal and spatial distribution of Cu, Pb, Zn, Cd, Hg, and As. Pollution condition, ecological risk, and potential sources were additionally analyzed. Results show that the annual mean concentrations of Cu, Pb, Zn, Cd, Hg, and As were 2.13-4.59, 0.212-1.480, 7.81-20.34, 0.054-0.279, 0.026-0.090, and 1.08-2.57 μg/L in the seawater, and were 16.34-28.35, 16.25-26.33, 67.32-97.61, 0.084-0.185, 0.029-0.061, and 6.09-14.08 μg/L in the sediments. A decreasing trend in Cu, Pb, Zn, Cd, and Hg concentrations and an increasing trend in As of the seawater were observed. However, in the sediment, the heavy metals demonstrated a rising trend, except for Hg. The single-factor pollution index showed an increasing trend in Cd and As in the seawater, depicting an enhanced pollution of Cd and As, while in the sediments, Cu, Pb, and As were in pollution-free level (average Geo-accumulation index (I_geo) values below 0) in general, and only occasional slight pollution occurred in individual years, e.g., As with 0.403 in 2016. The mean I_geo values of Cd ranged from - 0.865 to 0.274 during 2011 to 2016, indicating that the pollution level of Cd was slight, but is likely to increase in the forthcoming years. The level of heavy metal contamination in sediments was low in 2011 (5.853) and 2012 (5.172), and moderate during 2013 to 2016 (in the range of 6.107 to 7.598), while the degree of potential ecological risk was low in the study period, except moderate in 2013 (125.107). The highest contamination degree and potential ecological risk appeared in 2013 (Cd = 7.598; RI = 125.107), while Cd and Hg contributed over 75% of the ecological risk. Overall, the results show low pollution level and low potential ecological risk in the northern Hangzhou Bay; however, more attention should be paid to the potential ecological risk due to Hg and Cd. Graphical abstract Spatial distribution of the heavy metal levels in the sediment of the coastal environment of the northern Hangzhou Bay on a long-term basis.

Display of quintuple glucagon-like peptide 1 (28-36) nonapeptide on Bacillus subtilis spore for oral administration in the treatment of type 2 diabetes

AIMS

To develop an oral delivery system of glucagon-like peptide 1 (GLP-1) (28-36) for treating type-2 diabetes, B.S-GLP-1(28-36), a recombinant Bacillus subtilis spores transformed with a plasmid vector encoding five consecutive GLP-1 (28-36) nonapeptides with an enterokinase site was constructed.

METHODS AND RESULTS

GLP-1(28-36) nonapeptide was successfully expressed on the surface of B. subtilis spores and validated by Western blot and immunofluorescence. The therapeutic effect of oral administration of B.S-GLP-1(28-36) spores was evaluated in type 2 diabetic model mice. The efficacy of recombinant spores was examined for a period of 13 weeks after oral administration in diabetic mice. At the end of the sixth week, diabetic mice with oral administration of BS-GLP-1(28-36) spores showed decreased blood glucose levels from 2·4 × 10^{- 2}  mol l^-1 to 1·7 × 10^{- 2}  mol l^-1 . By the ninth week, the mean fasting blood glucose level in the experimental group was significantly lower than that in the control group 30 min after injection of pyruvate. At the end of the 10th week of oral administration, the blood glucose of the experimental group was significantly lower than that of the control group after intraperitoneal injection of glucose. By the 12th week, fasting blood glucose level and fasting insulin level were measured in all mice, the results showed that the recombinant spores increased the insulin sensitivity of mice.

CONCLUSIONS

The results of pathological observation showed that the recombinant spores also had a certain protective effect on the liver and islets of mice, and the content of GLP-1(28-36) in the pancreas of the experimental group was increased.

SIGNIFICANCE AND IMPACT OF THE STUDY

The results of this study revealed that GLP-1(28-36) nonapeptides can reduce blood glucose and play an important role in the treatment of type 2 diabetes.

[Etiology and molecular-epidemiological characteristics of viral meningo-encephalitis in Zhejiang province, 2002-2018]

Objective: To understand the pathogens and molecular-epidemiologic characteristics of viral meningo-encephalitis in Zhejiang province during 2002 to 2018. Methods: All the samples were collected from suspected patients admitted to the hospitals under the monitoring program. Of the total samples, 2 173 were cerebrospinal fluids while the other 455 were stool specimens. Cerebrospinal fluid (CSF) samples were subject to real-time qPCR for the detection of Human enterovirus (HEV), Mumps virus (MuV), Herpes simplex virus (HSV), Cytomegalovirus (CMV) and Japanese encephalitis virus (JEV). Stool sample were subject to real-time qPCR for HEV. ELISA was used to detect the IgM antibodies in CSF, in the 5 kinds of virus mentioned above. VP1 genes from all RNA-positive specimen were amplified, sequenced, for typing and for evolution analysis. Results: 871 (40.1%) of the 2 173 samples were detected as HEV nucleic acid positive during 2002 to 2018. 654 (38.1%) of the 1 718 CSF sample were HEV nucleic acid positive while 217 (47.7%) of the 455 stool sample were HEV nucleic acid positive. Among the total positive nucleic acid sample, 670 of them were VP1 sequence positive, including 5 HEV-A and 665 HEV-B. There were 23 HEV serotypes, including Coxsackievirus (CV) CVA4, CVA6, CVA9, CVA10, CVB1-5, Echovirus (EchoV; E) E3, E4, E6,E7, E9, E11, E14, E16, E18, E21, E25, E30, E33 and EV-71. The top three serotypes went to E30, E6 and CVB5. These three serotypes presented enhanced viral activity in every several years. 795 CSF samples were detected as virus nucleic acid positive, including 374 HEV, 6 MuV, 5 HSV and 5 CMV, from 2012 to 2015 and in 2018. 5 kinds of IgM antibodies were detected simultaneously in 368 CSF samples, including 2 HEV positive, 6 JEV positive and 1 MuV positive for 5 viruses, respectively. Except for EV-71, there were 517 EchoV and 152 CV viruses presented, with the ratio of 3.4∶1. These two kinds of viruses alternately changed for each predominant epidemic strains in every 3-5 years. Based on VP1, results from the phylogenetic tree showed that HEV from Zhejiang province clustered into HEV-A and HEV-B clades respectively. E30 developed both h and i sub-genotypes. Conclusions: HEV-B seemed the main pathogen for viral meningo-encephalitis in Zhejiang province. Ratio of positive detection on EchoV was significantly higher than that on CV. These two kinds of virus alternately presented changing tendency in every several years. Predominant epidemic strains E30, CVB5 and E6 were presenting enhanced viral activity, also in every several years. High correlation was found in both HEV viral activity from the surveillance sites and in time line of the viral meningo-encephalitis outbreaks.

Increased serum periostin concentrations are associated with the presence of diabetic retinopathy in patients with type 2 diabetes mellitus

PURPOSE

To determine the association between serum periostin and the presence of diabetic retinopathy (DR).

METHODS

Serum periostin was detected in 114 healthy subjects, 122 patients with type 2 diabetes mellitus (T2DM) and 159 patients with DR and compared among groups. Clinical data and other laboratory measurements such as glycated hemoglobin (HbA1c), lipid profiles, serum creatinine (Cr) and high-sensitivity CRP (hsCRP) were also collected and compared among groups. For subgroup analysis, patients with DR were divided into a non-proliferated diabetic retinopathy (NPDR) group and a proliferated diabetic retinopathy (PDR) group. Multivariate analysis was performed using logistic regression models.

RESULTS

The serum periostin level was significantly higher in patients with diabetic retinopathy compared with healthy subjects and patients with T2DM (both P < 0.001, respectively). Also, the periostin level was significantly higher in the PDR group compared to the NPDR group (P = 0.044). Multivariate logistic regression revealed that serum periostin was independently associated with the presence of DR in patients with T2DM (P < 0.001). The receiver operating characteristic (ROC) curves for DR development using serum periostin showed that the area under the receiver operating characteristic curves (AUC) was 0.838 (P < 0.001).

CONCLUSIONS

The current study demonstrated that serum periostin is significantly associated with the presence of DR in patients with T2DM and is an independent risk factor of DR.

[Clinical study of hydrogen-rich saline in the treatment of moderate to severe allergic rhinitis]

Objective:To investigate the effectiveness and safety of nasal lavage with hydrogen-rich saline in the treatment of moderate to severe allergic rhinitis.Method:Twenty patients with moderate to severe persistent allergic rhinitis were treated with normal saline and hydrogen-rich saline lavage the nasal cavity. The study was randomized doubl-blind self-control study. The symptoms and signs score, treatment index and total effective rate were evaluated before and after treatment, and the nasal conjunctivitis related quality of life questionnaire (BQLQ) was used to evaluate the life quality of patients.Result:There were significant differences of the symptoms, signs scores, the treatment index, the total efficiency and BQLQ between the two kinds of lavage fluid used for patients before and after treatment(P<0.05). No significant adverse reactions occurred during follow-up.Conclusion:Hydrogen-enriched saline is safe and effective for allergic rhinitis.

Plasma vascular endothelial growth factor B levels are increased in patients with newly diagnosed type 2 diabetes mellitus and associated with the first phase of glucose-stimulated insulin secretion function of β-cell

PURPOSE

To detect plasma vascular endothelial growth factor B (VEGF-B) in individuals with different glucose tolerance and investigate the relationship between plasma VEGF-B levels and the first phase of glucose-stimulated insulin secretion.

METHODS

A cross-sectional study was conducted involving 45 patients with newly diagnosed type 2 diabetes mellitus (T2DM), 37 patients with impaired glucose regulation (IGR), and 39 Normal glucose tolerance (NGT) subjects, all of whom underwent intravenous glucose tolerance test. Plasma VEGF-B levels were assayed by ELISA. The first phase of insulin secretion was evaluated by acute insulin response (AIR), the area under the curve of the first-phase (0-10 min) insulin secretion (AUC) and glucose disposition index (GDI).

RESULTS

The T2DM and IGR groups had higher plasma VEGF-B levels than the NGT group (P < 0.01). Plasma VEGF-B levels were negatively correlated with AIR, AUC, GDI, HOMA-β (P < 0.01), and positively correlated with plasma glucose, HbA1c, triglyceride, free fatty acid (FFA), fasting insulin, and HOMA-IR (P < 0.01). Logistic regression analysis revealed that higher VEGF-B levels [145.59-180.07 pg/ml, OR 3.55 (95% CI 1.05-12.02) and >180.07 pg/ml, OR 3.64 (95% CI 1.16-11.42)] were related to a greater probability of β-cell hypofunction, compared with low VEGF-B levels (<145.59 pg/ml). After adjusting for triglyceride or FFA, the association between VEGF-B levels and β-cell hypofunction disappeared (P > 0.05).

CONCLUSIONS

Our study provides evidence that plasma VEGF-B levels were higher in patients with newly diagnosed T2DM, and were strongly associated with glucose and lipid metabolism and the first-phase insulin secretion function of β-cells. VEGF-B may be involved in the mechanism of β-cell dysfunction in T2DM.

TRAF3IP3, a novel autophagy up-regulated gene, is involved in marginal zone B lymphocyte development and survival

Tumour necrosis factor receptor-associated factor 3 (TRAF3) interacting protein 3 (TRAF3IP3; also known as T3JAM) is expressed specifically in immune organs and tissues. To investigate the impact of TRAF3IP3 on immunity, we generated Traf3ip3 knock-out (KO) mice. Interestingly, these mice exhibited a significant reduction in the number of common lymphoid progenitors (CLPs) and inhibition of B cell development in the bone marrow. Furthermore, Traf3ip3 KO mice lacked marginal zone (MZ) B cells in the spleen. Traf3ip3 KO mice also exhibited a reduced amount of serum natural antibodies and impaired T cell-independent type II (TI-II) responses to trinitrophenol (TNP)-Ficoll antigen. Additionally, our results showed that Traf3ip3 promotes autophagy via an ATG16L1-binding motif, and MZ B cells isolated from mutant mice showed a diminished level of autophagy and a high rate of apoptosis. These results suggest that TRAF3IP3 contributes to MZ B cell survival by up-regulating autophagy, thereby promoting the TI-II immune response.

Corticosteroids and β₂-agonists upregulate mitogen-activated protein kinase phosphatase 1: in vitro mechanisms

BACKGROUND AND PURPOSE

Airway remodelling is a consequence of long-term inflammation and MAPKs are key signalling molecules that drive pro-inflammatory pathways. The endogenous MAPK deactivator--MAPK phosphatase 1 (MKP-1)--is a critical negative regulator of the myriad pro-inflammatory pathways activated by MAPKs in the airway.

EXPERIMENTAL APPROACH

Herein we investigated the molecular mechanisms responsible for the upregulation of MKP-1 in airway smooth muscle (ASM) by the corticosteroid dexamethasone and the β₂-agonist formoterol, added alone and in combination.

KEY RESULTS

MKP-1 is a corticosteroid-inducible gene whose expression is enhanced by long-acting β₂-agonists in an additive manner. Formoterol induced MKP-1 expression via the β₂-adrenoceptor and we provide the first direct evidence (utilizing overexpression of PKIα, a highly selective PKA inhibitor) to show that PKA mediates β₂-agonist-induced MKP-1 upregulation. Dexamethasone activated MKP-1 transcription in ASM cells via a cis-acting corticosteroid-responsive region located between -1380 and -1266 bp of the MKP-1 promoter. While the 3'-untranslated region of MKP-1 contains adenylate + uridylate elements responsible for regulation at the post-transcriptional level, actinomycin D chase experiments revealed that there was no increase in MKP-1 mRNA stability in the presence of dexamethasone, formoterol, alone or in combination. Rather, there was an additive effect of the asthma therapeutics on MKP-1 transcription.

CONCLUSIONS AND IMPLICATIONS

Taken together, these studies allow us a greater understanding of the molecular basis of MKP-1 regulation by corticosteroids and β₂-agonists and this new knowledge may lead to elucidation of optimized corticosteroid-sparing therapies in the future.

IκBα glutathionylation and reduced histone H3 phosphorylation inhibit eotaxin and RANTES

Airway smooth muscle cells (ASMCs) secrete eotaxin and RANTES (regulated on activation, normal T-cell expressed and secreted) in response to tumour necrosis factor (TNF)-α, which is inhibited by the nuclear factor (NF)-κB inhibitor dimethylfumarate (DMF). NF-κB/IκB (inhibitor of NF-κB) glutathionylation and changes in chromatin remodelling can inhibit NF-κB activity. In this study, we determined whether NF-κB/IκB glutathionylation and reduced histone H3 phosphorylation might underlie the inhibitory effect of DMF on NF-κB activity, and eotaxin and RANTES secretion. Primary human ASMCs were treated with DMF, diamide and/or glutathione (GSH) ethylester (OEt) prior to TNF-α stimulation and were subsequently analysed by ELISA, electrophoretic mobility shift assay, immunofluorescence, co-immunoprecipitation or immunoblotting. DMF reduced intracellular GSH and induced IκBα glutathionylation (IκBα-SSG), which inhibited IκBα degradation, NF-κB p65 nuclear entry and NF-κB/DNA binding. In addition, DMF inhibited the phosphorylation of histone H3, which was possibly mediated by the inhibitory effect of DMF on mitogen- and stress-activated protein kinase (MSK)-1. However, p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase MAPK and MAPK phosphatase-1, upstream of MSK-1, were not inhibited by DMF. Importantly, DMF-mediated effects on NF-κB, histone H3, eotaxin and RANTES were reversed by addition of GSH-OEt. Our data suggest that DMF inhibits NF-κB-dependent eotaxin and RANTES secretion by reduction of GSH with subsequent induction of IκBα-SSG and inhibition of histone H3 phosphorylation. Our findings offer new potential drug targets to reduce airway inflammation in asthma.

Phosphorylation of Crk on tyrosine 251 in the RT loop of the SH3C domain promotes Abl kinase transactivation

Here, we report the identification and characterization of a novel tyrosine phosphorylation site in the carboxy-terminal Src Homology 3 (SH3) (SH3C) domain of the Crk adaptor protein. Y251 is located in the highly conserved RT loop structure of the SH3C, a region of Crk involved in the allosteric regulation of the Abl kinase. Exploiting kinase assays to show that Y251 is phosphorylated by Abl in vitro, we generated affinity-purified antisera against phosphorylated Y251 in Crk and showed that Abl induces phosphorylation at Y251 in vivo, and that the kinetics of phosphorylation at Y251 and the negative regulatory Y221 site in vitro are similar. Y251 on endogenous Crk was robustly phosphorylated in chronic myelogenous leukemia cell lines and in A431 and MDA-MB-468 cells stimulated with epidermal growth factor. Using streptavidin-biotin pull downs and unbiased high-throughput Src Homology 2 (SH2) profiling approaches, we found that a pY251 phosphopeptide binds specifically to a subset of SH2 domains, including Abl and Arg SH2, and that binding of pY251 to Abl SH2 induces transactivation of Abl 1b. Finally, the Y251F Crk mutant significantly abrogates Abl transactivation in vitro and in vivo. These studies point to a yet unrealized positive regulatory role resulting from tyrosine phosphorylation of Crk, and identify a novel mechanism by which an adaptor protein activates a non-receptor tyrosine kinase by SH2 domain displacement.

Characterization of a murine thymic CD4(+) T cell subset-TCRalphabeta (+) 3G11 (-) 6C10 (-) CD4 (+) CD8 (-) thymocytes

The presence of a relatively mature CD4(+) CD8(-) (SP) T cell subset in mouse thymus has been demonstrated. Composing of 10% of total CD4SP thymocytes, this subset is defined by the absence of 3G11 and 6C10 expression with a phenotype of CD69(+/-), HSA(med/lo) and heterogeneous for Qa-2 expression. The proliferation capability of TCRalphabeta(+) 3Gl l(-) 6C10(-) CD4(+) CD8(-) thymocytes was high while using Con A stimulus. And Con A stimulation could result in secretion of IL4, IL-10, IL-6 and a little amount of IFNgamma. IL-2 was barely detectable. This is distinct from typical Th0 type cytokines. The cells of this subset were NK1.1 negative, but strongly expressed GATA-3 mRNA. The results suggest that the CD4(+) subset of 3G11(-) 6C10(-) NK1.1(-) phenotype possesses immunocompetent cells with functions characteristic of Th2-like cytokines, which may indicate the cells at transitional status from Th0 to Th2, with a propensity to Th2.

Histamine and tryptase modulate asthmatic airway smooth muscle GM-CSF and RANTES release

Degranulating mast cells are increased in the airway smooth muscle (ASM) of asthmatics, where they may influence ASM function. The aim of the present study was to determine whether histamine and tryptase modulate ASM cell granulocyte-macrophage colony-stimulating factor (GM-CSF) and RANTES (regulated on activation, normal T-cell expressed and secreted) release and also to examine which receptors are involved in this release. Confluent, quiescent ASM cells from asthmatic and nonasthmatic donors were treated with histamine (1 microM-100 microM) with and without histamine receptor antagonist pre-treatment, or the protease-activated receptor (PAR)-2 agonists tryptase (0.5-5 nM) and SLIGKV (100 and 400 microM). The cells were then stimulated with interleukin (IL)-1beta and/or tumour necrosis factor (TNF)-alpha (10 ng.mL(-1)) or left unstimulated for 24 h. Release of GM-CSF and RANTES was determined by ELISA and prostaglandin (PG)E(2) measured by enzyme immunoassay. Neither histamine nor tryptase induced ASM GM-CSF or RANTES secretion. However, histamine increased IL-1beta-induced GM-CSF release and markedly reduced TNF-alpha-induced RANTES release by both asthmatic and nonasthmatic cells to a similar extent, but did not modulate PGE(2) release. All changes involved activation of the histamine H1 receptor as they were partially or fully blocked by chlorpheniramine, but not ranitidine. Tryptase, via its proteolytic activity, also potentiated GM-CSF, but not RANTES, release from asthmatic and nonasthmatic ASM cells induced by both cytokines. PAR-2 involvement in the tryptase potentiation was unlikely because SLIGKV had no effect. In conclusion, mast cells, through histamine and tryptase, may locally modulate airway smooth muscle-induced inflammation in asthma.

In vitro studies of lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is associated with abnormal airway smooth muscle that leads to the characteristic pathology of lung nodule formation and destruction of lung tissue. The current authors have previously identified abnormal behaviour of airway smooth muscle cells from patients with asthma. In this study, cells and tissue sections derived from patients with LAM (n=7), asthma (n=8), and nonasthmatic controls (n=9) were compared. The presence of the antigen human melanosome (HM)B-45 was investigated, along with the proliferation and release of extracellular matrix proteins, release of endogenous prostaglandin E2 (PGE2), vascular endothelial growth factor and connective tissue growth factor, and the expression of integrins. Positive HMB-45 staining was found in all LAM patients and no controls. Proliferation of LAM cells was not different from control cells nor was its inhibition by beta-agonists, corticosteroids, rapamycin or PGE2. However, endogenous PGE2 levels were markedly decreased in LAM cells, and this was associated with decreased expression of the inducible form of cyclooxygenase (COX-2). The increased levels of connective tissue growth factor seen in asthma cells were not observed in LAM. Elastin mRNA in response to transforming growth factor-beta stimulation was markedly lower in LAM cells than either asthma or control cells. In conclusion, lymphangioleiomyomatosis cells exhibit abnormal properties in vitro that may contribute to pathophysiology and symptomatology in patients with lymphangioleiomyomatosis.

Inflammatory mediator release in normal bronchial smooth muscle cells is altered by pregnant maternal and fetal plasma independent of asthma

Studies have shown that pregnancy can alter the pathophysiology of a pre-existing maternal disease such as asthma. However, the mechanisms that alter maternal asthma during pregnancy are presently unknown. Previous work has demonstrated that human bronchial smooth muscle (BSM) cells produce inflammatory factors in response to nonpregnant, atopic plasma. The aim of this study was to determine whether circulating pregnancy-derived factors in maternal and fetal plasma can stimulate inflammatory mediator release in BSM cells in the presence and absence of maternal asthma. Cultured human BSM cells were exposed to maternal and fetal plasma from normal pregnancies and pregnancies complicated by asthma. Inflammatory mediator release was determined by enzyme-linked immunosorbent assay (ELISA). Both maternal and fetal plasma from asthmatic and nonasthmatic individuals significantly increased production of interleukin (IL)-6 (ANOVA, P<0.001), regulated upon activation, normal T-cell expressed and secreted (RANTES) (ANOVA, P<0.01), and soluble intercellular cell-adhesion molecule-1 (sICAM-1) (ANOVA, P<0.01). There was no difference in inflammatory mediator release in response to asthma and nonasthmatic plasma. Eotaxin release was increased by pregnant asthmatic plasma (ANOVA, P<0.05). The results of this study suggest that circulating pregnancy-related factors can activate asthma-associated mediators in BSM cells. This change in BSM function may be one mechanism that contributes to increased asthma severity during pregnancy.

Mechanisms of serum potentiation of GM-CSF production by human airway smooth muscle cells

Inflammation and vascular leakage are prevalent in asthma. This study aimed to elucidate the mechanisms involved in serum potentiation of cytokine-induced granulocyte macrophage colony stimulating factor (GM-CSF) production by human airway smooth muscle cells and to identify possible factors responsible. Serum-deprived cells at low density were stimulated with TNF-alpha and IL-1beta for 24 h. Human AB serum (10%), inhibitors of RNA and protein synthesis or specific signaling molecules, or known smooth muscle mitogens were then added for 24 h. Culture supernatants were analyzed for GM-CSF levels, and cells were harvested to assess viability, cell cycle progression, GM-CSF-specific mRNA content, and p38 phosphorylation. Serum potentiated GM-CSF release when added before, together with (maximal), or after the cytokines. The potentiation involved both new GM-CSF-specific mRNA production and protein synthesis. The mitogens IGF, PDGF, and thrombin all potentiated GM-CSF release, and neutralizing antibodies for EGF, IGF, and PDGF reduced the serum potentiation. Inhibitor studies ruled as unlikely the involvement of p70(S6kinase) and the MAPK p42/p44, two signaling pathways implicated in proliferation, and the involvement of the MAPK JNK, while establishing roles for p38 MAPK and NF-kappaB in the potentiation of GM-CSF release. Detection of significant p38 phosphorylation in response to serum stimulation, through Western blotting, further demonstrated the involvement of p38. These studies have provided evidence to support p38 being targeted to interrupt the cycle of inflammation, vascular leakage and cytokine production in asthma.

Structure Dependence of NO Adsorption and Dissociation on Platinum Surfaces

The influence of surface structure on NO chemisorption and dissociation on Pt[100]-(1x1), Pt[211], and Pt[410] has been studied using density functional theory slab calculations with the generalized gradient corrections. The presence of steps on Pt[211] strengthens the NO-surface chemisorption bond, but the barrier for NO dissociation remains high. On the other hand, the steps on Pt[410] help to stabilize the N and O adatoms that form upon dissociation and the transition state. The calculated barrier of 80.2 kJ/mol on Pt[410] is in good agreement with experiment. These results show that both the presence of steps and the nature of the steps are important to activate NO. An ensemble of square-arranged Pt atoms has been identified as an important feature in activating the N-O bond.

Partial and generalized epilepsy with febrile seizures plus and a novel SCN1A mutation

BACKGROUND

Generalized epilepsy with febrile seizures plus (GEFS+) is an autosomal dominant syndrome characterized by febrile seizures (FS) and a variety of afebrile generalized seizure types. GEFS+ has previously been linked to mutations in two genes encoding the voltage-gated sodium channel alpha-subunit (SCN1A) and beta1-subunit (SCN1B). We studied a large family with FS and partial as well as generalized seizure types.

METHODS

All but two living affected family members were interviewed and examined. Information on deceased affected family members was sought. EEG for 11 affected family members and one unaffected family member were obtained. Genetic linkage analysis and mutation screening of SCN1A were performed on blood samples from 16 affected individuals and their first-degree relatives.

RESULTS

There were 27 affected family members; 18 were alive at the time of the study. All affected family members had FS; seven had FS only, and 19 also had afebrile seizures. Eleven individuals continued to have FS beyond 6 years of age. FS were complex in 12 family members, usually with prolonged duration. The index patient had right temporal lobe epilepsy and hippocampal sclerosis. Four other patients had strong historical evidence of temporal lobe epilepsy, and three others had nonlocalizing evidence of partial epilepsy. Pedigree analysis indicated autosomal dominant transmission. All affected individuals who were tested and one asymptomatic individual had a sodium channel mutation of SCN1A, an A-->C transversion at nucleotide 3809 resulting in the substitution of lysine 1270 by threonine in the D3/S2 segment (designated as K1270T).

CONCLUSIONS

Our findings indicate that partial epilepsy preceded by FS can be associated with sodium channel mutations and may represent a variant of GEFS+.

Airway smooth muscle cell proliferation is increased in asthma

Increased airway smooth muscle (ASM) within the bronchial wall of asthmatic patients has been well documented and is likely to be the result of increased muscle proliferation. We have for the first time been able to culture ASM cells from asthmatic patients and to compare their proliferation rate with that of nonasthmatic patients. Asthmatic ASM cell cultures (n = 12) were established from explanted lungs and endobronchial biopsies. Nonasthmatic ASM cells (n = 10) were obtained from explanted tissue from patients with no airway disease, emphysema, carcinoma, and fibrosing alveolitis. Cell counts, tritiated thymidine incorporation, and cell cycle analysis were conducted over 7 d. Asthmatic ASM cell numbers at Days 3, 5, and 7 were significantly higher than corresponding values for nonasthmatic cells (p < 0.05). Tritiated thymidine incorporation was increased 3.2-fold in asthmatic cells compared with nonasthmatic cells within the first 24 h (p = 0.026). Flow cytometric analysis of DNA content on Days 1 and 2 revealed that a significantly greater percentage of asthmatic ASM cells were in the G2 + M phase (p < 0.05). This study shows for the first time that proliferation of ASM cells is increased in patients with asthma and provides evidence for an intrinsic abnormality in the ASM cell in this disease.

KEYWORDS

asthma; human airway smooth muscle; cell culture; cell proliferation; hyperplasia

Dislocation-controlled perforated layer phase in a PEO- b-PS diblock copolymer

Small angle x-ray analyses show that the shear-induced hexagonal perforated layer phase in a poly(ethylene oxide)- b-polystyrene diblock copolymer consists of trigonal (R3;m) twins and a hexagonal (P6(3)/mmc) structure, with trigonal twins being majority components. Transmission electron microscopy reveals that the hexagonal structure is generated through sequential intrinsic stacking faults on the second layer from a previous edge dislocation line, while the trigonal twins are formed by successive intrinsic stacking faults on neighboring layers due to the plastic deformation under mechanical shear.

Dependence of lymphopenia-induced T cell proliferation on the abundance of peptide/ MHC epitopes and strength of their interaction with T cell receptors

Factors that affect naive T cell proliferation in syngeneic lymphopenic hosts were investigated. 2C T cell receptor (TCR) transgenic T cells lacking both CD8 and CD4 survived but hardly proliferated. Proliferation of CD8(+) 2C cells was proportional to the abundance of cognate peptide/MHC complexes and was severely inhibited by injection of anti-CD8 antibody. Weakly reactive self-peptides slightly enhanced CD8(+) 2C cell proliferation whereas a potent agonist peptide promoted much more rapid proliferation, but inflammation-stimulating adjuvant had only a small effect on the rate of cell proliferation. The findings suggest that under uniform lymphopenic conditions, the widely different rates of proliferation of T cells expressing various TCR, or the same TCR in the presence or absence of CD8, reflect the strength of interaction between TCR and MHC associated with particular self-peptides.

The role of sexual related Y gene detection in the diagnosis of patients with gonadal dysgenesis

OBJECTIVE

To clarify the role of sexual related Y (SRY) gene detection in the diagnosis of gonadal dysgenesis.

METHODS

Sixteen cases of gonadal dysgenesis were included in this study: 5 with androgen insensitivity syndrome, 1 with 17-alpha-hydroxylase deficiency, 4 with true hermaphrodite, 2 with 45, X/46, XY gonadal dysgenesis, 1 with 45, X gonadal dysgenesis, 1 with XY pure gonadal dysgenesis, 1 with testicular regression, and 1 XY female who gave birth to a normal baby. SRY gene was detected by using polymerase chain reaction (PCR) in blood and gonad samples and by direct sequencing of the SRY motif.

RESULTS

Among the 16 cases, 15 were blood SRY positive, among which 13 (86.7%) showed the presence of testicular tissue, and 2 showed ovaries without testicular tissue. One SRY negative case showed the presence of testicular tissue. In 3 cases, SRY detection in gonadal tissue correlated with pathological findings but not with blood karyotype. The correlation between peripheral blood SRY and the pathology of the gonads was 81.25% and the correlation between the presence of peripheral blood Y chromosome and pathology of the gonads was 68.75%. Sequencing of the SRY motif in an XY female who gave birth to a normal baby showed no mutation.

CONCLUSIONS

SRY detection is more sensitive and specific than blood karyotype in the prediction of the presence of testicular tissue. Peripheral blood karyotype does not necessarily reflect gonadal type. There may be testicular related factors other than the SRY gene.

The production of extracellular matrix proteins by human passively sensitized airway smooth-muscle cells in culture: the effect of beclomethasone

Airway remodeling is a key feature of persistent asthma. Part of the remodeling process involves the laying down of extracellular matrix (ECM) proteins within the airways. In this study we compared the production of ECM proteins by human airway smooth-muscle (ASM) cells in culture after exposure to 10% serum from an asthmatic individual or 10% serum from a nonasthmatic individual with or without beclomethasone (0.01 to 100 nM). Enzyme-linked immunosorbent assays were done with antibodies to human fibronectin; perlecan; elastin; the laminin beta(1), gamma(1), beta(2), alpha(1) chains; thrombospondin; chondroitin sulfate; collagen types I, III, IV, and V; versican; and decorin. Serum from the asthmatic individual, when compared with that from the nonasthmatic individual, caused a significant increase in the production of fibronectin, perlecan, laminin gamma(1), and chondroitin sulfate. Beclomethasone caused a significant reduction in the number of cells exposed to serum from either the asthmatic or nonasthmatic individual, but did not reverse the increase in ECM protein induced by the former. These results suggest an interaction between the ASM and the allergic process that may alter components of the airway wall in asthma, and that corticosteroids may not prevent the fibrosis induced by resident cells within the airways.

[Application of mitotic index and proliferating cell nuclear antigen index in monitoring the change of rat endometrium after administration of estrogen and progestin]

OBJECTIVE

To investigate the mitotic index (MI) and proliferating cell nuclear antigen (PCNA) index in monitoring the rat endometrium during estrogen and progestin administration.

METHODS

One hundred and sixty Sprague-Dolly rats were randomly divided into seven groups. The 1st and 2nd group were normal estrous (E) and ovariectomized (OVX) control. The other groups received estradiol (E2V) only or combined with medroxyprogesterone(MPA) which imitated the clinical regimen in different dosage and different time before sacrificed. Uteri sections were stained with HE and immunohistochemical procedures to detect mitosis and PCNA.

RESULTS

The MI and PCNA index were similar in the luminal and glandular cells. Both markers were low in the two control groups and increased with the E2V dosage in the treatment group. But if E2V was given for 1 to 21 days, the MI increased during the first 3 days and then dropped to low level and kept to the end. PCNA index increased in the first 3 days and decreased to a low level on the 4th day and then increased gradually to a high level until the last day. In the continuous regimen, both markers decreased as the MPA dosage increased. In the cyclic regimen, The MI reached to a significant low level nearly to zero in almost each ratio. Addition of MPA for 10 days, PCNA index at the ratio of 1:4.0 could be reduced to a low level and addition for 5 days, PCNA index in each subgroup was still as high as the positive control even though the dosage of MPA increased several times to 1:8.0.

CONCLUSIONS

This study suggests that PCNA index can reflect both the effect of estrogen and progestogen. PCNA index is better than mitotic index in reflecting the change of endometrium.

Effect of murine thymic epithelial cell line (MTEC1) on the functional expression of CD4(+)CD8(-) thymocyte subgroups

To determine the effect of thymic stromal cells on the functional maturation of CD4 single-positive (SP) thymocytes, the functional status of isolated CD4 SP thymocyte subgroups was investigated by means of cell proliferation and cytokine production in response to concanavalin A (Con A) prior and after co-culturing with a murine thymic epithelial cell line (MTEC1). Mouse medullary CD4 SP thymocytes were phenotypically divided into seven discrete subgroups predicted to reflect the maturation pathway from newly emerging CD4 SP thymocytes to terminally differentiated cells. For functional analysis, six major subgroups (6C10(+)CD69(+), 6C10(-)CD69(+), 6C10(-)CD69(-)3G11(+)Qa-2(-), 6C10(-)CD69(-)3G11(+)Qa-2(+), 6C10(-)CD69(-)3G11(-)Qa-2(-) and 6C10(-)CD69(-)3G11(-)Qa-2(+)) cells were isolated and their functional status in response to Con A stimulation assessed. A functional hierarchy is revealed among these subgroups, consistent with their phenotypic maturation status, which may imply that these cells undergo a functional maturation process within thymic medulla. The function of cytokine production by CD4 SP thymocytes is acquired in a stepwise manner from a low to high level and characterized by T(h)0-type cytokines in the main stream of differentiation pathway. However, a minor subgroup that appeared at the late stage as 3G11(-)6C10(-) cells was biased to produce T(h)2-type cytokines. Nevertheless, the functional capacity of the final two Qa-2(+) subgroups of CD4 SP thymocytes was still significantly lower than that of spleen CD4(+) T cells. After co-cultivation with MTEC1 cells, four subgroups of TCRalphabeta(+)CD4(+)CD8(-) thymocytes exhibited significantly higher levels of proliferation capability and modulation in cytokine production capability. However, co-culturing with MTEC1 cells did not change the pattern of T(h)0- or T(h)2-like cytokine production by respectively medullary CD4 SP thymocyte subgroups nor could MTEC1 induce CD4 SP thymocytes to secrete T(h)1-type cytokines. The results suggest that MTEC1 can regulate the functional status of these thymocyte subgroups.

Apoptotic cells actively inhibit the expression of CD69 on Con A activated T lymphocytes

Although apoptosis is commonly viewed as a silent cell death without damage to adjacent tissues, the effect of apoptosis on immunity has been unclear. We have investigated the influence of apoptotic cells on T-cell activation. The K562 or HL-60 human leukemia cell lines that had been induced apoptosis by FTY720 or cycloheximide (CHX) were added into the culture of mouse spleen cells stimulated with Con A. Six to 20 h later, the expression of CD69, an early T-cell activation antigen, was detected using flowcytometry. Living cells and necrotic cells served as control groups. Apoptotic K562 or HL-60 cells induced by either FTY720 or CHX unanimously inhibited CD69 expression on the CD3+ mouse T cells while living and necrotic cells did not. The inhibition was proportional to the number of apoptotic cells and was different in the T-cell subsets, showing a rapid and transient inhibition on the CD3+CD8+ T-cell activation but with a slow and continuous inhibition on CD3+CD8- T-cell activation. In conclusion, the apoptotic cells actively inhibit a T-cell activation that is independent of the cell lines or the apoptotic inducers, indicating that the apoptotic cells dominantly regulate T-cell immunity.

Spontaneous activation of hamster oocytes in vitro

OBJECTIVES

To observe the time of spontaneous activation of hamster oocytes and to find out the early signs of hamster oocytes activation.

METHODS

First, 63 hamster oocytes including activated and non-activated oocytes (group A) and 51 non-activated oocytes (group B) were injected with human sperm and checked for fertilization after 16-18 hours. Then, 20 hamster oocytes were cultured in vitro in medium with or without calcium and examined under light microscope every half an hour up to 9 hours.

RESULTS

Under light microscope, hamster oocytes activation were observed to undergo 4 stages: metaphase II stage without meiotic spindle, appearance of meiotic spindle near the first polar body, protrusion of oolemma, and complete extrusion of second polar body with pronucleus formation. After culture for 1.5 hours in vitro, 30%-40% of the oocytes demonstrated meiotic spindle; but after 9 hours, 50% showed complete activation. Culture in medium without calcium showed a little delay in the process of activation. The earliest sign of spontaneous activation in hamster oocytes was the appearance of meiotic spindle near the first polar body. Although group A and B showed no difference, the damage rate was lower in group B (19.7% +/- 16.6%) than in group A (35.9% +/- 5.7%) (P = 0.08), whereas the fertilization rate (18.3% +/- 10.9%) was higher in group B than in group A (14.2% +/- 8.7%) (P = 0.135).

CONCLUSIONS

Hamster oocytes may be activated spontaneously early after their removal. It is important to recognize the earliest sign of spontaneous activation and perform intracytoplasmic sperm injection (ICSI) before it happens.

Phenotypic identification of the subgroups of murine T-cell receptor alphabeta+ CD4+ CD8- thymocytes and its implication in the late stage of thymocyte development

Phenotypic analysis of the medullary-type CD4+ CD8- [CD4 single-positive (SP)] thymocytes has revealed phenotypic heterogeneity within this cell population. The characteristic phenotype of mature peripheral T cells can be uniquely marked as Qa-2+ HSA- CD69-, whereas in the medullary-type CD4 SP thymocytes, the expression patterns of many markers were quite different. This suggests that there are many subgroups in the population, which reflects that medullary-type CD4 SP thymocytes may undergo phenotypic maturation. According to the results of two-colour flow cytometry, seven discrete phenotypes were identified by the expression capacity of Qa-2, HSA, CD69, 3G11 and 6C10 molecules. Consequently, the phenotypic precursor-progeny relationship can be envisaged as: 3G11- 6C10+ CD69+ HSAhi -->3G11+ 6C10+ CD69+ HSAhi --> 3G11+ 6C10- CD69+ HSAint -->3G11+ 6C10- CD69- HSAint Qa-2- -->3G11+ HSA-/lo Qa-2lo. At the stage of 3G11+ 6C10- CD69- HSAint Qa-2-, a branch pathway could be initiated, which gave rise to 3G11- HSAl degrees Qa-2- cells, which then, in turn, developed into 3G11- HSA-/loQa-2hi cells, a minor subgroup of the most mature CD4 SP cells. Consistent with this predicted pathway, experiments indicated that the first two subgroups were still cortisone sensitive, whereas the others were cortisone resistant. The cells in the last two Qa-2-positive subgroups are probably ready for emigration into the periphery.

[The effects of sex hormone on blood vessels]

OBJECTIVE

The protective mechanism of sex hormone on blood vessels was investigated to provide evidences for clinical use of hormone replacement therapy in postmenopausal women.

METHODS

To observe the effects of 17 beta-estradiol (E2), progesterone(P), testosterone (T) and E2 combined with P on the relaxation of umbilical arterial rings (UAR) as well as production of nitric oxide (NO) in cultured umbilical endothelial cells(HUVEC) in vitro.

RESULTS

The results showed that 10(-9)-10(-6) mol/L E2 dilation of UAR, but 10(-5) mol/L E2 showed vague effect. P or T had no relaxation effect, but releasing nitric oxide. When in combined trial P at 10(-5) mol/L inhibited the relaxation effect of E2 at 10(-7)-10(-5) mol/L but didn't inhibit E2 10(-9) mol/L. In HUVEC 10(-9)-10(-5) mol/L E2 stimulated the release of nitric oxide when cells incubated for 10 min and 30 min, but did not influence the NO release at 60 min. P and T have different effects on the release of nitric oxide at different concentrations and incubation time. P also inhibited the NO release induced by E2.

CONCLUSIONS

The results indicated that P actually inhibited the relaxation response and induction of NO release by E2, especially at the high concentration. Therefore, we suggested that to use low doses of E2 combined with low dose P for hormone replacement therapy in prevention and treatment of cardiovascular diseases in postmenopausal patient.

Comparison of bone mass in forearm, lumbar vertebra and hip by single and/or dual energy X-ray absorptiometry

OBJECTIVE

Bone mineral density (BMD) was measured in normal Chinese women with single X-ray absorptiometry (SXA) and dual energy X-ray absorptiometry (DEXA). These two methods were compared to evaluate the sensitivity in reflecting bone loss.

METHODS

Measurements were performed in 300 women aged 20 to approximately 79 (5 for each age). The 8mm distal, 1/4 distal, ultra distal site of the nondominant forearm were measured with SXA; the AP spine (L2-4), right femoral neck (Neck), Ward's triangle (Ward) and trochantor (Troch) were measured with DEXA. Ten women had 5 repeated measurements to evaluate the reproducibility of the equipments.

RESULTS

The BMD peak for Neck and Ward was found between age 20 to approximately 29, for ultra distal and L2-4 at age 30 to approximately 39, for 8mm distal, 1/4 distal and Troch at age 40 to approximately 49. After reaching the peak values, BMD at all sites decreased with increasing age. The highest rate of yearly loss of BMD was at 8mm distal. Results of measurement showed significant correlation between SXA and DEXA. Comparing with premenopausal women, the bone loss rate in postmenopausal women was faster and highest up to 11 to approximately 15 years and the highest rate was at the Ward.

CONCLUSION

The present study gives the normal values of BMD at seven sites for normal Chinese women. The ages of BMD peak were different at seven sites. The yearly loss of BMD was highest at 8mm distal, it seemed to be the sensitive region for bone loss with age. The postmenopausal women had highly significantly loss bone mass than the premenopausal women. Comparing with premenopause, postmenopause BMD for Ward's triangle with DEXA seemed to be most sensitive to the effect of menopause.

[Phenotypic analysis of TCR alpha beta+ CD4+CD8- medullary thymocytes]

Phenotypic analysis of the medullary-type CD4+CD8- (CD4SP) thymocytes have revealed phenotypic heterogeneity within these cells. The phenotype of mature peripheral T cells is Qa-2+ HSA- CD69-, whereas in the medullary-type CD4SP thymocytes, the expression pattern of many markers were quite different, suggesting that the medullary-type CD4SP thymocytes may undergo phenotypic maturation. According to the results of two-color cytometry, seven discrete phenotypes were defined by the relative expression of Qa-2, HSA, CD69, 3G11 and 6C10: 3G11-6C10+CD69+HSAhi-->3G11+6C10+CD69+ HSAhi-->3G11+6C10-CD69+HSAint-->3G11+6C10- CD69-HSAint Qa-2(-)-->3G11+HSAlo/-Qa-2lo, at the same time, 3G11+6C10-CD69-HSAint Qa-2(-)-->3G11-HSAlo Qa-2(-)-->3G11-HSAlo/- Qa-2hi, the last two Qa-2 positive subsets could exit the thymus and home into periphery.

AMPA receptor activation and phosphatase inhibition affect neonatal rat respiratory rhythm generation

1. We investigated the role of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptors and their regulation in affecting respiratory-related neurones in a neonatal rat medullary slice that spontaneously generates respiratory-related rhythm and motor output in the hypoglossal (XII) nerve. 2. Bath application of the AMPA receptor antagonist 1-(4-aminophenyl)-4-methyl-7,8-methylenedioxy-5H-2, 3-benzodiazepine (GYKI) completely blocked XII nerve activity, as well as respiratory-related synaptic drives in neurones within the preBötzinger Complex (preBotC), site of rhythm generation in the slice. 3. Local application of GYKI to the preBötC blocked respiratory rhythm. Local application of AMPA to the preBötC increased rhythm frequency and depolarized respiratory-related neurones. 4. In the presence of tetrodotoxin (TTX), GYKI completely blocked the inward current induced by local application of AMPA, but not that induced by kainate. 5. Local application of okadaic acid, a membrane-permeable inhibitor of phosphatase 1 and 2A, to the preBotC increased the frequency of respiratory motor discharge. 6. Intracellular application of microcystin, a membrane-impermeable inhibitor of phosphatase 1 and 2A, enhanced endogenous inspiratory drive and exogenous AMPA-induced current (in the presence of TTX) in preBotC inspiratory neurones. Both the enhanced inspiratory drive and the increased AMPA-induced current were completely blocked by GYKI. 7. We suggest that AMPA receptor activation and AMPA receptor modulation by phosphorylation are crucial for the rhythm generation within the preBötC.