Exo84c-regulated degradation is involved in the normal self-incompatible response in Brassicaceae

The self-incompatibility system evolves in angiosperms to promote cross-pollination by rejecting self-pollination. Here, we show the involvement of Exo84c in the SI response of both Brassica napus and Arabidopsis. The expression of Exo84c is specifically elevated in stigma during the SI response. Knocking out Exo84c in B. napus and SI Arabidopsis partially breaks down the SI response. The SI response inhibits both the protein secretion in papillae and the recruitment of the exocyst complex to the pollen-pistil contact sites. Interestingly, these processes can be partially restored in exo84c SI Arabidopsis. After incompatible pollination, the turnover of the exocyst-labeled compartment is enhanced in papillae. However, this process is perturbed in exo84c SI Arabidopsis. Taken together, our results suggest that Exo84c regulates the exocyst complex vacuolar degradation during the SI response. This process is likely independent of the known SI pathway in Brassicaceae to secure the SI response.

Exo84c interacts with VAP27 to regulate exocytotic compartment degradation and stigma senescence

In plants, exocyst subunit isoforms exhibit significant functional diversity in that they are involved in either protein secretion or autophagy, both of which are essential for plant development and survival. Although the molecular basis of autophagy is widely reported, its contribution to plant reproduction is not very clear. Here, we have identified Exo84c, a higher plant-specific Exo84 isoform, as having a unique function in modulating exocytotic compartment degradation during stigmatic tissue senescence. This process is achieved through its interaction with the ER localised VAP27 proteins, which regulate the turnover of Exo84c through the autophagy pathway. VAP27 recruits Exo84c onto the ER membrane as well as numerous ER-derived autophagosomes that are labelled with ATG8. These Exo84c/exocyst and VAP27 positive structures are accumulated in the vacuole for degradation, and this process is partially perturbed in the exo84c knock-out mutants. Interestingly, the exo84c mutant showed a prolonged effective pollination period with higher seed sets, possibly because of the delayed stigmatic senescence when Exo84c regulated autophagy is blocked. In conclusion, our studies reveal a link between the exocyst complex and the ER network in regulating the degradation of exocytosis vesicles, a process that is essential for normal papilla cell senescence and flower receptivity.

Keep in contact: multiple roles of endoplasmic reticulum-membrane contact sites and the organelle interaction network in plants

Functional regulation and structural maintenance of the different organelles in plants contribute directly to plant development, reproduction and stress responses. To ensure these activities take place effectively, cells have evolved an interconnected network amongst various subcellular compartments, regulating rapid signal transduction and the exchange of biomaterial. Many proteins that regulate membrane connections have recently been identified in plants, and this is the first step in elucidating both the mechanism and function of these connections. Amongst all organelles, the endoplasmic reticulum is the key structure, which likely links most of the different subcellular compartments through membrane contact sites (MCS) and the ER-PM contact sites (EPCS) have been the most intensely studied in plants. However, the molecular composition and function of plant MCS are being found to be different from other eukaryotic systems. In this article, we will summarise the most recent advances in this field and discuss the mechanism and biological relevance of these essential links in plants.

Autophagosome Biogenesis in Plants: An Actin Cytoskeleton Perspective

At the subcellular level, the cytoskeleton regulates cell structure, organelle movement, and cytoplasmic streaming. Autophagy is a process to remove unwanted biomaterials or damaged organelles through double membrane compartments known as autophagosomes. Autophagosome biogenesis requires vesicle trafficking between donor and acceptor compartments, membrane expansion, and fusion, which is very likely to be regulated by the cytoskeleton. Recent studies have demonstrated that by knocking out key actin-regulating proteins, autophagosome biogenesis is inhibited. However, the formation of ATG8 positive structures are not affected when the entire actin network is disrupted. Here, we discuss this paradox and propose the function of the actin cytoskeleton in plant autophagy.

Home quarantine compliance is low in children with fever during COVID-19 epidemic

BACKGROUND

The coronavirus disease 2019 (COVID-19) outbreak began in China at the end of 2019. The disease is highly infectious. In order to prevent and control the epidemic situation, the state has issued a series of measures to guide the prevention and control of the epidemic. At the same time, it also introduced the measure of home isolation for children with fever. However, due to the nature of children, the implementation of the home isolation turned out to be quite difficult, and questions regarding the home isolation were brought out by parents when seeing doctors. For this reason, we decided to conduct this study.

AIM

To study factors that influence home quarantine compliance in children with fever during the COVID-19 epidemic.

METHODS

A total of 495 paediatric patients with respiratory tract infection and fever were selected from the general fever clinic at Xiamen Children's Hospital from February 6-27, 2020. On day 8 after the hospital visit, follow-up was conducted by telephone to evaluate the compliance of home quarantine.

RESULTS

Among the ten quarantine measures, the proportion of families adhering to keeping 1.5 m distance, proper hand hygiene, wearing masks at home, and proper cough etiquette was very low (< 30% for each measure). Our analysis showed that compliance was related to gender and age of children, gender and age of primary caregiver, number of children in the family, and intensity of information on quarantine measures. We observed that compliance increased with the age of children. Compared with children whose caregivers were young adults, children with elderly caregivers were 2.461 times more likely to show poor compliance. Furthermore, children who received intensive information on quarantine measures had significantly better compliance.

CONCLUSION

Compliance of children with fever to quarantine measures at home is low during the COVID-19 epidemic. Strengthening education on the quarantine measures is critical to improve compliance, in particular in young children with elderly caregivers.

Long noncoding RNAs involve in resistance to Verticillium dahliae, a fungal disease in cotton

Long noncoding RNAs (lncRNAs) have several known functions in plant development, but their possible roles in responding to plant disease remain largely unresolved. In this study, we described a comprehensive disease-responding lncRNA profiles in defence against a cotton fungal disease Verticillium dahliae. We further revealed the conserved and specific characters of disease-responding process between two cotton species. Conservatively for two cotton species, we found the expression dominance of induced lncRNAs in the Dt subgenome, indicating a biased induction pattern in the co-existing subgenomes of allotetraploid cotton. Comparative analysis of lncRNA expression and their proposed functions in resistant Gossypium barbadense cv. '7124' versus susceptible Gossypium hirsutum cv. 'YZ1' revealed their distinct disease response mechanisms. Species-specific (LS) lncRNAs containing more SNPs displayed a fiercer inducing level postinfection than the species-conserved (core) lncRNAs. Gene Ontology enrichment of LS lncRNAs and core lncRNAs indicates distinct roles in the process of biotic stimulus. Further functional analysis showed that two core lncRNAs, GhlncNAT-ANX2- and GhlncNAT-RLP7-silenced seedlings, displayed an enhanced resistance towards V. dahliae and Botrytis cinerea, possibly associated with the increased expression of LOX1 and LOX2. This study represents the first characterization of lncRNAs involved in resistance to fungal disease and provides new clues to elucidate cotton disease response mechanism.

NLRP3 inflammasome activation during myocardial ischemia reperfusion is cardioprotective

BACKGROUND

The innate immune receptor NLRP3 recognizes tissue damage and initiates inflammatory processes through formation multiprotein complexes with the adaptor protein ASC and caspase-1, i.e. NLRP3 inflammasomes, which through cleavage of pro-IL-1β mediates release of bioactive IL-1β. We hypothesized that NLRP3 mediates tissue damage during acute myocardial infarction (MI) and sought to investigate the mechanisms herein in an experimental MI model in mice.

METHODS AND RESULTS

The left coronary artery (LCA) of WT, NLRP3(-/-) and ASC(-/-) mice of both genders was ligated for 30 min followed by 3 or 24 h reperfusion. For pre-conditioning studies, the TLR2 agonist Pam3CSK4 or PBS was injected intraperitoneally 60 min prior to LCA ligation. For mechanistic investigations, blood plasmas and left ventricle tissues were collected, and a hypothesis-driven selection of protein or mRNA targets was investigated. Surprisingly, hearts from NLRP3-deficient mice featured larger infarct size than WT mice (p = 0.0048). In general, there were only modest changes with no significant pattern in myocardial infiltration of neutrophils and macrophages and systemic and myocardial cytokine expression between the three genotypes. Preconditioning with the TLR2 agonist Pam3CSK4 induced Akt phosphorylation and reduced infarct size in WT but not NLRP3 -or ASC -deficient hearts.

CONCLUSION

Absence of NLRP3 results in increased myocardial infarct size after in vivo ischemia reperfusion, seemingly due to dysfunction of the cardioprotective RISK pathway. Our data imply that NLRP3 contributes to cardio-protection during I/R and do not support a role for NLRP3 or ASC inhibition in the management of acute MI including revascularization therapy.

Myocardial β(2) -adrenoceptor gene delivery promotes coordinated cardiac adaptive remodelling and angiogenesis in heart failure

BACKGROUND AND PURPOSE

We investigated whether β(2) -adrenoceptor overexpression could promote angiogenesis and improve blood perfusion and left ventricular (LV) remodeling of the failing heart.

EXPERIMENTAL APPROACH

We explored the angiogenic effects of β(2) -adrenoceptor overexpression in a rat model of post-myocardial infarction (MI) heart failure (HF). Cardiac adenoviral-mediated β(2) -adrenoceptor overexpression was obtained via direct intramyocardial injection 4-weeks post-MI. Adenovirus(Ad)-GFP and saline injected rats served as controls. Furthermore, we extended our observation to β(2) -adrenoceptor -/- mice undergoing MI.

KEY RESULTS

Transgenes were robustly expressed in the LV at 2 weeks post-gene therapy, whereas their expression was minimal at 4-weeks post-gene delivery. In HF rats, cardiac β(2) -adrenoceptor overexpression resulted in enhanced basal and isoprenaline-stimulated cardiac contractility at 2-weeks post-gene delivery. At 4 weeks post-gene transfer, Ad-β(2) -adrenoceptor HF rats showed improved LV remodeling and cardiac function. Importantly, β(2) -adrenoceptor overexpression was associated with a markedly increased capillary and arteriolar length density and enhanced in vivo myocardial blood flow and coronary reserve. At the molecular level, cardiac β(2) -adrenoceptor gene transfer induced the activation of the VEGF/PKB/eNOS pro-angiogenic pathway. In β(2) -adrenoceptor-/- mice, we found a ~25% reduction in cardiac capillary density compared with β(2) -adrenoceptor+/+ mice. The lack of β(2) -adrenoceptors was associated with a higher mortality rate at 30 days and LV dilatation, and a worse global cardiac contractility compared with controls.

CONCLUSIONS AND IMPLICATION

β(2) -Adrenoceptors play an important role in the regulation of the angiogenic response in HF. The activation of VEGF/PKB/eNOS pathway seems to be strongly involved in this mechanism.

Plasma soluble HLA-G is a potential biomarker for diagnosis of colorectal, gastric, esophageal and lung cancer

Human leukocyte antigen-G (HLA-G) is a novel tumor marker and its soluble isoforms produce secretory proteins. Increased soluble HLA-G (sHLA-G) levels have been reported in patients with melanoma, neuroblastoma, lymphoproliferative disorders, breast, ovarian and colorectal carcinoma when compared to healthy controls or subjects with benign neoplasms. The aim of this study is to investigate whether or not plasma sHLA-G can be used as a potential biomarker for cancer diagnosis. We measured plasma sHLA-G levels in 166 patients with early stages of colorectal cancer (CRC, n = 37), gastric cancer (GC, n = 28), esophageal squamous cell carcinoma (ESCC, n = 58) and non-small cell lung cancer (NSCLC, n = 43), and compared them to healthy controls (n = 260) by using a specific HLA-G enzyme-linked immunosorbent assay (ELISA). We found that plasma sHLA-G levels were significantly higher in cancer patients than in healthy controls (all P < 0.0001). The areas under the receiver-operating characteristic (ROC) curves for sHLA-G were 0.97, 0.91, 0.98 and 0.80 for healthy controls vs CRC, GC, ESCC and NSCLC, respectively. At 100% specificity, the highest sensitivity achieved to detect CRC, GC, ESCC and NSCLC was 94% [95% confidence interval (CI), 89-99], 85% (95% CI, 76-94), 91% (95% CI, 88-94) and 51% (95% CI, 43-59) at a cutoff value of 49 U/ml, respectively. These findings suggest that plasma sHLA-G may be a useful molecule in the differential diagnosis of these malignancies against healthy controls.

Induced abortion and duration of third stage labour in a subsequent pregnancy

We set out to evaluate the impact of first trimester induced abortion on the duration of third stage labour and related complications in a subsequent pregnancy. The study was conducted in Shanghai city at 15 general hospitals (or maternity and infant health institutes) from November 1993 to March 1998. We identified all nulliparae who came for antenatal care within the first 63 days of pregnancy (2953); the women were divided into two cohorts according to their previous history of first trimester induced abortion. After enrollment, the women were interviewed five times from recruitment until 42 days after delivery. We included in the study all 1363 women who had a singleton vaginal live birth. Of these women, 703 were primigravida (non-exposed), 534 had had one previous first trimester induced abortion, and 126 women had had two or more first trimester induced abortions. The duration of third stage labour in minutes was longer in women with one or more previous induced abortions (mean=7.32 minutes) compared with primigravid women (mean=6.79 minutes). Prolonged third stage labour (>30 minutes) following one or more induced abortions was seen for 3.4% versus 1.0% in primigravid women. After adjusting for a number of potential confounders, women with one or more previous first trimester induced abortions had an odds ratio of prolonged third stage labour of 2.59 (95%C.I.=1.06-6.37) compared with primigravida, especially after an interpregnancy interval of more than 6 months (OR=3.24, 95%C.I.=1.29-8.13). The odds ratio of prolonged third stage labour was 3.14 (95%C.I.=1.22-8.09) if gestational age at the time of the induced abortion exceeded 49 days. Women with a first trimester induced abortion had no significantly increased risk of postpartum haemorrhage or retained placenta. It was concluded that a history of one or more first trimester induced abortions was related to an increased risk of prolonged third stage labour in the following pregnancy, particularly if the induced abortion was performed after 49 days of gestation.

Fetal macrosomia and adolescence obesity: results from a longitudinal cohort study

OBJECTIVE

To assess the association between fetal macrosomia and adolescent obesity.

DESIGN

Longitudinal cohort study of the association between macrosomia and adolescent obesity.

SUBJECTS

Between 1 October 2005 and 1 February 2007, a follow-up study of live-born infants born in 1993-1995 in Wuxi, a suburban area of Shanghai, was conducted. Subjects with birth weight > 4000 g were selected as the exposed. For each exposed subject, one subject with a birth weight of 2500-4000 g, matched by year of birth, sex of infant, and type of institute at birth, was chosen as non-exposed. Clinical data were collected by structured interview and physical examination. Obesity was defined as body mass index (weight (kg)/height (m(2))) higher than the sex-age-specific criteria by the working group on obesity in China. Distribution of baseline characteristics and adolescent obesity rate between the exposed and non-exposed groups was compared.

RESULTS

A total of 1435 pairs of exposed and non-exposed subjects were included in the final analysis. No major difference in baseline characteristics (other than birth weight) was found between the exposed and non-exposed groups. Obesity rate was significantly higher in the exposed group (2.9%) than in the non-exposed group (1.6%). Adolescent obesity rates were 1.4, 1.9, 2.6, and 5.6%, respectively, in study subjects with a birth weight of 2500-3499, 3500-3999, 4000-4499, and > or =4500 g. The association between birth weight and adolescent obesity remained essentially the same when mother's demographic and anthropometric factors, breast feeding, and adolescent life-style factors were adjusted.

CONCLUSION

Compared with infants of normal birth weight, infants with birth weight >4000 g, especially those >4500 g, are at increased risk of adolescent obesity.

Thioredoxin reduces post-ischemic myocardial apoptosis by reducing oxidative/nitrative stress

BACKGROUND AND PURPOSE

Thioredoxin (Trx) is an oxidoreductase that prevents free radical-induced cell death in cultured cells. Here we assessed the mechanism(s) underlying the cardioprotective effects of Trx in vivo.

EXPERIMENTAL APPROACH

The effects of myocardial ischemia (30 min) and reperfusion were measured in mice, with assays of myocardial apoptosis, superoxide production, NOx and nitrotyrosine content, and myocardial infarct size. Recombinant human Trx (rhTrx, 0.7-20 mg kg(-1), i.p.) was given 10 min before reperfusion.

KEY RESULTS

Treatment with 2 mg kg(-1) rhTrx significantly decreased myocardial apoptosis and reduced infarct size (P<0.01). Nitrotyrosine content of cardiomyocytes was markedly reduced in rhTrx-treated animals (P<0.01). To further identify the mechanisms by which rhTrx may exert its anti-nitrative effect, iNOS expression and production of NOx and superoxide were determined. Treatment with rhTrx had no significant effect on iNOS expression or NOx content in the ischemic/reperfused heart. However, it markedly upregulated mSOD and reduced tissue superoxide content. To further establish a causative link between the anti- peroxynitrite effect and the cardioprotective effect of rhTrx, cultured adult cardiomyocytes were incubated with SIN-1, a peroxynitrite donor, (50 microM for 3 h) resulting in a nitrotyrosine content comparable to that seen in the ischemic/reperfused heart and causing significant cardiomyocyte apoptosis (P<0.01). Treatment with rhTrx markedly decreased SIN-1 induced apoptosis (P<0.01).

CONCLUSIONS AND IMPLICATIONS

These results demonstrate that Trx is a novel anti-apoptotic and cardioprotective molecule that exerts its cardioprotective effects by reducing ischemia/reperfusion-induced oxidative/nitrative stress.

Early anti-apoptosis treatment reduces myocardial infarct size after a prolonged reperfusion

OBJECTIVE

Significant myocardial apoptosis occurs in ischemia/reperfused hearts. However, the contribution of apoptosis to the development of myocardial injury remains controversial. The present study attempted to obtain evidence that inhibition of apoptosis at early reperfusion can reduce myocardial infarction after prolonged reperfusion.

METHODS

Adult male rats were subjected to 30 min ischemia and 4 (apoptosis assay) or 24 h (myocardial infarction determination) of reperfusion and treated with vehicle, SB 239063, insulin or insulin plus wortmannin.

RESULTS

Treatment with SB 239063 or insulin markedly decreased myocardial apoptosis (10.6 +/- 1.5% and 7.9 +/- 0.9% respectively, P < 0.01 vs. vehicle) and significantly reduced infarct size (43 +/- 3.6% and 35 +/- 2.9%, respectively, P < 0.01 vs. vehicle). Most interestingly, inhibition of insulin signaling with wortmannin to block insulin signaling not only blocked insulin's anti-apoptotic effect, but also abolished its infarct reduction property.

CONCLUSION

These data indicate that apoptosis contributes to the development of myocardial infarction, and inhibition of apoptosis at early reperfusion reduces the myocardial infarction.

Summary evaluations of risk factors related to infant mortality

The authors discuss risk factors related to infant mortality. "The size and magnitude of these risk factors vary across different countries and regions. In order to more accurately describe the relationship between risk factors and infant mortality, risk factors should be quantified, making it possible to estimate the degree of risk associated with infant deaths. This article introduces some risk factors and their evaluation method."

Adenosine A1 receptor antagonist prolongs survival in the hypoxic rat

The hypothesis that adenosine A1 receptor (A1AdoR) selective antagonism limits cardiac depression and prolongs survival during acute global hypoxia was tested in a postinsult treatment model using KW-3902 ([8-(noradamantan-3-yl)-1,3-dipropylxanthine]), an A1AdoR selective antagonist. Rats were anesthetized, paralyzed, then ventilated with 8% O2 (hypoxia). In protocol I, 5 min after hypoxia, rats were treated with saline, drug vehicle, or KW-3902 (0.1 mg/kg i.v.). In protocol II, KW-3902 treatment occurred 2.5, 5, or 7.5 min after hypoxia. In protocol I, after hypoxia, left ventricular contractility, heart rate, and systemic mean arterial blood pressure decreased rapidly in saline-and vehicle-treated groups. In contrast, KW-3902 significantly attenuated the decline in these variables. Survival time (the time from the commencement of hypoxia until death) was more prolonged with KW-3902 (109.5 +/- 9.1 min) than with saline (37.6 +/- 5.0 min) or vehicle (35.0 +/- 4.2 min) (p < 0.001). In protocol II, survival time increased from 29.2 +/- 5.5 min in the 7.5-min treatment group to 109.5 +/- 9.5 min (5-min group) and 245.9 +/- 26.1 min (2.5-min group; p < 0.001). KW-3902 prolongs survival in this model, presumably by antagonizing A1AdoR-mediated inhibition of cardiac function. Also, treatment efficacy is highly time dependent.

[Effect of Shajiang black soil amended by coal fly ash on ecological factors and residue of heavy metal in wheat field]

The effect of Shajiang black soil amended by coal fly ash on ecological factors in wheat field and residua of Cd, Cr, Pb, Hg and As were studied by pot experiment. The results showed that applying coal fly ash into Shajiang black soil could decrease soil density, soil proportion and clay content, but increase soil porosity, filtration coefficient and soil temperature. Moreover, it could promote water evaporating when soil moisture was high and keep soil water when lower than 10%. It also could facilitate activity of soil micro-organism and promote soil nutrient transforming. With (6-18) x 10(4) kg.hm-2 coal fly ash applied in Shajiang black soil, the accumulated quantity of Cd, Cr, Pb, Hg and As in soil and in wheat grain were lower than international standard index of pollution. Therefor, Shajiang black soil amended by coal fly ash was safe and reliable within the above range.

Vanadium, molybdenum, and sodium triethanolamine complexes derived from an assembly system containing tetrathiometalate and triethanolamine

The reaction system composed of triethanolamine (TEA) and tetrathiovanadate in the presence of MeONa (MeOLi) or NaNH2 was studied to afford vanadium and alkali metal TEA complexes. Complexes [M subsetV6O6[N(CH2CH2O)2(CH2CH2OH)]6]2S6 (M = Na (1), Li (2)) contain two cyclic V((IV)) [12]metallacrown-6 cations linked by a polysulfide S6(2-) anion. Also separated from the reaction system is a novel sodium TEA complex [[Na(TEA)]2S6]n (3), in which parallel coordination chains [Na(TEA)+]n are connected by O-H...S hydrogen bonds forming 3-D network structure. Variable-temperature conductance of 3 was determined to display semiconductor feature. The desulfurization of VS4(3-) was observed to form S6(2-) anion and/or S8 molecule in the synthetic reactions of 1-3. A striking contrast was noted that MoS4(2-) did not desulfurize in the similar reaction to that of VS4(3-) with TEA, and a Na/TEA complex containing MoS4(2-), (Et4N)2[Na2(mu-TEA)2(CH3OH)2](MoS4)2 (4), was obtained instead. The S...H-O and O...H-O hydrogen bonds play an important role in forming the one- or three-dimensional structures for all these complexes by the linkages between clusters and chains. The IR spectrum indicates the structural similarity of complexes 1 and 2. For complex 4, the Mo=S stretch vibration at 468 cm(-1) showing widening and slight red-shift and the slight movement of the 1H NMR signals of TEA ligand to downfield are considered to be the influence of the S...H-O hydrogen bonds. Variable temperature magnetic susceptibility data were collected for complex 1. The effect magnetic moment per V6 unit varies gradually from 4.04 muB at 300 K to 6.24 muB at 5 K, exhibiting ferromagnetic interaction. Heisenberg-type vector-coupling model and molecular field approximation were used to treat the interaction between the paramagnetic sites and gave a good fitting result: J = 3.97 cm(-1), J' = 1.99 cm(-1), g = 1.99, F = 3.64 x 10(-3). Density functional calculation was also performed to complex 1 and its Li, K analogues. The lowest total bonding energy of -874.001 eV was obtained for [Na subsetV6(mu3-O)6] complex containing six unpaired electrons, indicating the stability of a V6 system with six independent spins S = 1/2. When the alkali metal ion is inserted into the [V6(mu3-O)6] cavity, the positive values of the bonding interaction (E(b)) indicate that the insertion depresses the total energy and that complexes 1 and 2 together with K+ complex may exist. However, the lowest E(b) value of the K+ complex implies its instability.

Effects of acetylcholine and atropine on plasticity of central auditory neurons caused by conditioning in bats

In the big brown bat (Eptesicus fuscus), conditioning with acoustic stimuli followed by electric leg-stimulation causes shifts in frequency-tuning curves and best frequencies (hereafter BF shifts) of collicular and cortical neurons, i.e., reorganization of the cochleotopic (frequency) maps in the inferior colliculus (IC) and auditory cortex (AC). The collicular BF shift recovers 180 min after the conditioning, but the cortical BF shift lasts longer than 26 h. The collicular BF shift is not caused by conditioning, as the AC is inactivated during conditioning. Therefore it has been concluded that the collicular BF shift is caused by the corticofugal auditory system. The collicular and cortical BF shifts both are not caused by conditioning as the somatosensory cortex is inactivated during conditioning. Therefore it has been hypothesized that the cortical BF shift is mostly caused by both the subcortical (e.g., collicular) BF shift and the activity of nonauditory systems such as the somatosensory cortex excited by an unconditioned leg-stimulation and the cholinergic basal forebrain. The main aims of our present studies are to examine whether acetylcholine (ACh) applied to the AC augments the collicular and cortical BF shifts caused by the conditioning and whether atropine applied to the AC abolishes the cortical BF shift but not the collicular BF shift, as expected from the preceding hypothesis. In the awake bat, we made the following findings. ACh applied to the AC augments not only the cortical BF shift but also the collicular BF shift through the corticofugal system. Atropine applied to the AC reduces the collicular BF shift and abolishes the cortical BF shift which otherwise would be caused. ACh applied to the IC significantly augments the collicular BF shift but affects the cortical BF shift only slightly. ACh makes the cortical BF shift long-lasting beyond 4 h, but it cannot make the collicular BF shift long-lasting beyond 3 h. Atropine applied to the IC abolishes the collicular BF shift. It reduces the cortical BF shift but does not abolish it. Our findings favor the hypothesis that the BF shifts evoked by the corticofugal system, and an increased ACh level in the AC evoked by the basal forebrain are both necessary to evoke a long-lasting cortical BF shift.

Identification of essential residues in 2',3'-cyclic nucleotide 3'-phosphodiesterase. Chemical modification and site-directed mutagenesis to investigate the role of cysteine and histidine residues in enzymatic activity

2',3'-Cyclic nucleotide 3'-phosphodiesterase (CNP; EC ) catalyzes in vitro hydrolysis of 3'-phosphodiester bonds in 2',3'-cyclic nucleotides to produce 2'-nucleotides exclusively. N-terminal deletion mapping of the C-terminal two-thirds of recombinant rat CNP1 identified a region that possesses the catalytic domain, with further truncations abolishing activity. Proteolysis and kinetic analysis indicated that this domain forms a compact globular structure and contains all of the catalytically essential features. Subsequently, this catalytic fragment of CNP1 (CNP-CF) was used for chemical modification studies to identify amino acid residues essential for activity. 5,5'-Dithiobis-(2-nitrobenzoic acid) modification studies and kinetic analysis of cysteine CNP-CF mutants revealed the nonessential role of cysteines for enzymatic activity. On the other hand, modification studies with diethyl pyrocarbonate indicated that two histidines are essential for CNPase activity. Consequently, the only two conserved histidines, His-230 and His-309, were mutated to phenylalanine and leucine. All four histidine mutants had k(cat) values 1000-fold lower than wild-type CNP-CF, but K(m) values were similar. Circular dichroism studies demonstrated that the low catalytic activities of the histidine mutants were not due to gross changes in secondary structure. Taken together, these results demonstrate that both histidines assume critical roles for catalysis.

Views of Chinese parents on the provision of contraception to unmarried youth

This study sought the views of Chinese parents on sex education and contraception for unmarried youth. Data were drawn from 16 focus group discussions conducted in eight sites in China in 1998-1999 with parents of unmarried children aged 18-24. While parents tended to recognise the reality of changing sexual norms, they were ambivalent with regard to sexual activity among young people and the provision of services to them. To prevent this ambivalence from posing a significant obstacle to the adoption of safe sex behaviours by young people, the dilemmas faced by parents need to be addressed through programmes for parents. Parents were clearly concerned for the well-being of their unmarried children, and keen to see their children protected from unwanted pregnancy and disease; they supported the provision of life skills education and the development of negotiation skills, self-esteem and the ability to exercise informed choice. Parents appeared willing for government to establish educational and service delivery programmes for the unmarried; it is important that government acts upon this.

Induced abortion and prematurity in a subsequent pregnancy: a study from Shanghai

To evaluate the impact of a first trimester induced abortion on the risks of low birth weight (LBW) and preterm birth in a subsequent pregnancy we conducted a pregnancy-based cohort study in Shanghai, China with recruitment from 15 general hospitals (or maternity and infant health institutes) from November 1993 to March 1998. Pregnant women with a history of induced abortion entered the abortion cohort and a reference cohort was established among women without such a history. All the subjects were enrolled before 64 days of gestation and interviewed five times until 42 days after delivery. Only singleton live births were analysed in this study. A total of 2953 pregnant women were enrolled and 2707 gave birth to live singletons. The overall incidence of LBW was 1.7%, 2.0% in the abortion cohort and 1.4% in the reference cohort. After controlling the potential confounders using logistic regression, the adjusted odds ratios were 1.7 (95% CI: 0.8-3.3) for LBW, 2.0 (95% CI: 0.9-4.7) for term LBW and 1.0 (95% CI: 0.6-1.5) for preterm birth, following an induced abortion pregnancy. Birth weight in the abortion cohort was 38.5 g higher than that of the reference cohort after adjustment for calendar year at recruitment, couples' occupation, education, age, infant sex, maternal body mass index at recruitment, contraceptive use and gestation age. Previous first trimester induced abortion did not significantly increase the risk of LBW or preterm birth. The study was performed in a low-risk population and results may not be applicable to other settings.

[The study of the foundation of the health organization of the Chinese People's Liberation Army (PLA)]

The PLA's health work was gradually founded and developed from 1927 when the army was established. General Medical Department of the Central Military Commission, which was the leading department of health work of the PLA, was established in 1931. Then, all kinds of health organizations were established and strengthened, and uniform leader system was formed. At the same time, health workers were trained and the laws were set up. The initiatory stage was accomplished in 1933. The primary founder of the PLA's health work was He Cheng.

Transcriptional regulation of 2',3'-cyclic nucleotide 3'-phosphodiesterase gene expression by cyclic AMP in C6 cells

It was recently shown that the two transcripts encoding the isoforms of 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP1 and CNP2) are differentially regulated during the process of oligodendrocyte maturation. In oligodendrocyte precursors, only CNP2 mRNA is present, whereas in differentiating oligodendrocytes, both CNP1 and CNP2 mRNAs are expressed. This pattern of CNP expression is likely due to stage-specific transcriptional regulation of the two CNP promoters during the process of oligodendrocyte differentiation. Here, we report the influence of increased intracellular cyclic AMP (cAMP) levels on the transcription of both CNP1 and CNP2 mRNAs in rat C6 glioma cells. We found that the transcription of CNP1 mRNA was significantly increased in comparison with that of CNP2 mRNA in cells treated with cAMP analogues to elevate intracellular cAMP levels. This up-regulation of CNP1 expression (a) is due to an increase of transcription, (b) requires de novo protein synthesis, and (c) requires the activity of protein kinase A. These results are physiologically significant and support the idea that a cAMP-mediated pathway is part of the molecular mechanisms regulating the expression of CNP1 in oligodendrocytes. The regulation of CNP1 promoter activity by cAMP was then investigated in stably transfected C6 cell lines containing various deletions of the CNP promoter directing the bacterial chloramphenicol acetyltransferase gene. We showed that the sequence between nucleotides -126 and -102 was essential for the cAMP-dependent induction of CNP1 expression. Gel retardation analysis showed that two protein-DNA complexes are formed between this sequence and nuclear factors from C6 cells treated or not treated with cAMP. This suggests that the induction of CNP1 mRNA transcription is not mediated by changes in binding of nuclear factors that interact directly with the -126/-102 sequence. Sequence analysis of this region revealed the presence of a putative activator protein-2 (AP-2) binding site. It is interesting that mutagenesis of this region resulted in a significant reduction in transcriptional responses to cAMP, implying a possible role for the AP-2 factor in the expression of CNP1. In addition, we have shown that putative binding sites for activator protein-4 and nuclear factor-1 adjacent to the AP-2 site are required for efficient induction of CNP1 expression by cAMP. Taken together, our results show that the cAMP-dependent accumulation of CNP1 mRNA appears to depend on the synergistic interaction of several regulatory elements.

The corticofugal system for hearing: recent progress

Peripheral auditory neurons are tuned to single frequencies of sound. In the central auditory system, excitatory (or facilitatory) and inhibitory neural interactions take place at multiple levels and produce neurons with sharp level-tolerant frequency-tuning curves, neurons tuned to parameters other than frequency, cochleotopic (frequency) maps, which are different from the peripheral cochleotopic map, and computational maps. The mechanisms to create the response properties of these neurons have been considered to be solely caused by divergent and convergent projections of neurons in the ascending auditory system. The recent research on the corticofugal (descending) auditory system, however, indicates that the corticofugal system adjusts and improves auditory signal processing by modulating neural responses and maps. The corticofugal function consists of at least the following subfunctions. (i) Egocentric selection for short-term modulation of auditory signal processing according to auditory experience. Egocentric selection, based on focused positive feedback associated with widespread lateral inhibition, is mediated by the cortical neural net working together with the corticofugal system. (ii) Reorganization for long-term modulation of the processing of behaviorally relevant auditory signals. Reorganization is based on egocentric selection working together with nonauditory systems. (iii) Gain control based on overall excitatory, facilitatory, or inhibitory corticofugal modulation. Egocentric selection can be viewed as selective gain control. (iv) Shaping (or even creation) of response properties of neurons. Filter properties of neurons in the frequency, amplitude, time, and spatial domains can be sharpened by the corticofugal system. Sharpening of tuning is one of the functions of egocentric selection.

Model of structural and functional adaptation of small conductance vessels to arterial hypotension

Vascular networks adapt structurally in response to local pressure and flow and functionally in response to the changing needs of tissue. Whereas most research has either focused on adaptation of the macrocirculation, which primarily transports blood, or the microcirculation, which primarily controls flow, the present work addresses adaptation of the small conductance vessels in between, which both conduct blood and resist flow. A simple hemodynamic model is introduced consisting of three parts: 1) bifurcating arterial and venous trees, 2) an empirical description of the microvasculature, and 3) a target shear stress depending on pressure. This simple model has the minimum requirements to explain qualitatively the observed structure in normotensive conditions. It illustrates that flow regulation in the microvasculature makes adaptation in the larger conductance vessels stable. Furthermore, it suggests that structural changes in response to hypotension can account for the observed decrease in the lower limit of autoregulation in chronically hypotensive vasculature. Independent adaptation to local conditions thus yields a coordinated set of structural changes that ultimately adapts supply to demand.

Can induction of systemic hypotension help prevent nidus rupture complicating arteriovenous malformation embolization?: analysis of underlying mechanism achieved using a theoretical model

BACKGROUND AND PURPOSE

Nidus rupture is a serious complication of intracranial arteriovenous malformation (AVM) embolotherapy, but its pathogenetic mechanisms are not well described. An AVM model based on electrical network analysis was used to investigate theoretically the potential role of hemodynamic perturbations for elevating the risk of nidus vessel rupture (Rrupt) after simulated AVM embolotherapy, and to assess the potential benefit of systemic hypotension for preventing rupture.

METHODS

Five separate hypothetical mechanisms for nidus hemorrhage were studied: 1) intranidal rerouting of blood pressure; 2) extranidal rerouting of blood pressure; 3) occlusion of draining veins with glue; 4) delayed thrombosis of draining veins; and 5) excessively high injection pressures proximal to the nidus. Simulated occlusion of vessels or elevated injection pressures were implemented into the AVM model, and electrical circuit analysis revealed the consequent changes in intranidal flow, pressure, and Rrupt for the nidus vessels. An expression for Rrupt was derived based on the functional distribution of the critical radii of component vessels. If AVM rupture was observed (Rrupt > or = 100%) at systemic normotension (mean pressure [P] = 74 mm Hg), the theoretical embolization was repeated under systemic hypotension (minor P = 70 mm Hg, moderate P = 50 mm Hg, or profound P = 25 mm Hg) to assess the potential benefit of this maneuver in reducing hemorrhage rates.

RESULTS

All five pathogenetic mechanisms under investigation were able to produce rupture of AVMs during or after embolotherapy. These different mechanisms had in common the capability of generating surges in intranidal hemodynamic parameters resulting in nidus vessel rupture. The theoretical induction of systemic hypotension during and after treatment was shown to be of significant benefit in attenuating these surges and reducing Rrupt to safer levels below 100%.

CONCLUSION

The induction of systemic hypotension during and after AVM embolization would appear theoretically to be of potential use in preventing iatrogenic nidus hemorrhage. The described AVM model should serve as a useful research tool for further theoretical investigations of AVM embolotherapy and its hemodynamic sequelae.

Experience-dependent plasticity in the auditory cortex and the inferior colliculus of bats: role of the corticofugal system

In the big brown bat, Eptesicus fuscus, the response properties of neurons and the cochleotopic (frequency) maps in the auditory cortex (AC) and inferior colliculus can be changed by auditory conditioning, weak focal electric stimulation of the AC, or repetitive delivery of weak, short tone bursts. The corticofugal system plays an important role in information processing and plasticity in the auditory system. Our present findings are as follows. In the AC, best frequency (BF) shifts, i.e., reorganization of a frequency map, slowly develop and reach a plateau approximately 180 min after conditioning with tone bursts and electric-leg stimulation. The plateau lasts more than 26 h. In the inferior colliculus, on the other hand, BF shifts rapidly develop and become the largest at the end of a 30-min-long conditioning session. The shifted BFs return (i. e., recover) to normal in approximately 180 min. The collicular BF shifts are not a consequence of the cortical BF shifts. Instead, they lead the cortical BF shifts. The collicular BF shifts evoked by conditioning are very similar to the collicular and cortical BF shifts evoked by cortical electrical stimulation. Therefore, our working hypothesis is that, during conditioning, the corticofugal system evokes subcortical BF shifts, which in turn boost cortical BF shifts. The cortical BF shifts otherwise would be very small. However, whether the cortical BF shifts are consequently boosted depends on nonauditory systems, including nonauditory sensory cortices, amygdala, basal forebrain, etc., which determine the behavioral relevance of acoustic stimuli.

Antagonism of the cardiodepressant effects of adenosine during acute hypoxia

OBJECTIVE

To determine whether pharmacologic antagonism of adenosine A1-receptor-mediated cardiovascular changes can improve cardiac function and prolong survival during systemic hypoxia.

METHODS

Rats were anesthetized with ketamine, instrumented [including left ventricular (LV) pressure transducing catheters], paralyzed with vecuronium, then ventilated to pCO2 = 35-40 torr. After 10 minutes of equilibration (baseline), treatment commenced with saline (n = 7), NPC-205, an adenosine A1 receptor selective antagonist, at doses of 1 mg/kg (n = 10) or 10 mg/kg (n = 10), or drug vehicle (n = 9). Ten minutes later, inspired oxygen was reduced to 5%.

RESULTS

Survival duration (min) post-hypoxia increased in a dose-dependent fashion from 10.4 +/- 1.4 (mean +/- SEM) with vehicle control to 23.0 +/- 4.7 and 41.1 +/- 5.7 with 1 and 10 mg/kg NPC-205, respectively (p < 0.000). Five minutes post-hypoxia, dose-dependent increases were also seen in the percentage of pre-hypoxic values of LV contractility [25.9 +/- 8.1 (vehicle), 39.5 +/- 9.6 (1 mg/kg NPC-205), and 56.5 +/- 8.7 (10 mg/kg NPC-205), p = 0.01], heart rate [60.6 +/- 8.3 (vehicle), 74.7 +/- 8.2 (1 mg/kg NPC-205), and 90.4 +/- 24.1 (10 mg/kg NPC-205), p = 0.02], and blood pressure [16.1 +/- 4.8 (vehicle), 28.8 +/- 8.6 (1 mg/kg NPC-205), and 51.7 +/- 8.2 (10 mg/kg NPC-205), p = 0.004].

CONCLUSIONS

The adenosine A1 selective antagonist prolonged survival in this model. This prolongation was attributed to inhibition of adenosine A1 receptor-mediated decline in cardiac inotropy and chronotropy. Adenosine A1 receptor-selective antagonists show promise as adjunctive therapy for hypoxia-induced cardiac insufficiency by prolonging the treatment window until more definitive resuscitation measures are taken.

Effect of aging on the negative chronotropic and anti-beta-adrenergic actions of adenosine in the rat heart

The effect of aging on the antiadrenergic actions of adenosine was studied in vitro and in vivo by using adult (6-month-old) and old (24-month-old) male Fischer 344 rats. In anesthetized animals, adenosine (0.01-0.1 micromol/kg), given as a rapid bolus into the right atrium, exerted a negative chronotropic effect manifested by a dose-dependent transient prolongation of sinus cycle length (SCL). This effect was similar in both age groups (n = 6, each; i.e., the percentage maximal prolongation of SCL (%deltaSCL) ranged from 12 +/- 2% to 63 +/-14% in the adult and from 20 +/- 7% to 57 +/- 15% in the old rats. In the presence of isoproterenol (0.2 microg/kg/min), the negative chronotropic action of adenosine was potentiated in the adult rats much more than in the old rats [i.e., %deltaSCL ranged from 60 +/- 28% to 183 +/- 48% vs. 40 +/- 12% to 70 +/- 13%, respectively (p < 0.05, adult vs. old)]. In the isolated perfused hearts, isoproterenol (1 microM for 1 min) exerted similar chronotropic and inotropic effects in adult (n = 9) and old hearts [n = 6; i.e., heart rate, left ventricular pressure (LVP), and LVdp/dt increased by 56 +/- 3%, 17 +/- 1%, and 37 +/- 2%, and 57 +/- 2%, 17 +/- 1%, and 35 +/- 3%, respectively, in the absence of, and by 27 +/- 2%, 7 +/- 1%, and 19 +/- 2% and 41 +/- 3%, 12 +/- 1%, and 25 +/-2% in the presence of adenosine (5 microM for 1 min)]. Adenosine administration after isoproterenol caused only an insignificant increase in coronary blood flow. Finally, the adenosine attenuation of either isoproterenol- or forskolin-induced production of 3',5'-cyclic adenosine monophosphate (cAMP) was significantly less in atrial membranes isolated from old versus adult rats (n = 6, each). It was concluded that in the old Fischer 344 rat hearts, the antiadrenergic action of adenosine is attenuated as compared with its action in adult rat hearts.

Analysis of genomic regions involved in regulation of the rabbit surfactant protein A gene in transgenic mice

The gene encoding surfactant protein (SP) A, a developmentally regulated pulmonary surfactant-associated protein, is expressed in a lung-specific manner, primarily in pulmonary type II cells. SP-A gene transcription in the rabbit fetal lung is increased by cAMP. To delineate the genomic regions involved in regulation of SP-A gene expression, lines of transgenic mice carrying fusion genes composed of various amounts of 5'-flanking DNA from the rabbit SP-A gene linked to the human growth hormone structural gene as a reporter were established. We found that as little as 378 bp of 5'-flanking DNA was sufficient to direct appropriate lung cell-selective and developmental regulation of transgene expression. The same region was also sufficient to mediate cAMP induction of transgene expression. Mutagenesis or deletion of either of two DNA elements, proximal binding element and a cAMP response element-like sequence, previously found to be crucial for cAMP induction of SP-A promoter activity in transfected type II cells, did not affect lung-selective or temporal regulation of expression of the transgene; however, overall levels of fusion gene expression were reduced compared with those of wild-type transgenes.