Improved Measurement of the Evolution of the Reactor Antineutrino Flux and Spectrum at Daya Bay

Reactor neutrino experiments play a crucial role in advancing our knowledge of neutrinos. In this Letter, the evolution of the flux and spectrum as a function of the reactor isotopic content is reported in terms of the inverse-beta-decay yield at Daya Bay with 1958 days of data and improved systematic uncertainties. These measurements are compared with two signature model predictions: the Huber-Mueller model based on the conversion method and the SM2018 model based on the summation method. The measured average flux and spectrum, as well as the flux evolution with the ^{239}Pu isotopic fraction, are inconsistent with the predictions of the Huber-Mueller model. In contrast, the SM2018 model is shown to agree with the average flux and its evolution but fails to describe the energy spectrum. Altering the predicted inverse-beta-decay spectrum from ^{239}Pu fission does not improve the agreement with the measurement for either model. The models can be brought into better agreement with the measurements if either the predicted spectrum due to ^{235}U fission is changed or the predicted ^{235}U, ^{238}U, ^{239}Pu, and ^{241}Pu spectra are changed in equal measure.

Precision Measurement of Reactor Antineutrino Oscillation at Kilometer-Scale Baselines by Daya Bay

We present a new determination of the smallest neutrino mixing angle θ_{13} and the mass-squared difference Δm_{32}^{2} using a final sample of 5.55×10^{6} inverse beta-decay (IBD) candidates with the final-state neutron captured on gadolinium. This sample is selected from the complete dataset obtained by the Daya Bay reactor neutrino experiment in 3158 days of operation. Compared to the previous Daya Bay results, selection of IBD candidates has been optimized, energy calibration refined, and treatment of backgrounds further improved. The resulting oscillation parameters are sin^{2}2θ_{13}=0.0851±0.0024, Δm_{32}^{2}=(2.466±0.060)×10^{-3}  eV^{2} for the normal mass ordering or Δm_{32}^{2}=-(2.571±0.060)×10^{-3}  eV^{2} for the inverted mass ordering.

[Immunogenicity of group A+C meningococcal polysaccharide conjugate vaccine in infants: A phase Ⅲ clinical trial study]

Objective: To evaluate the immunogenicity of group A+C meningococcal polysaccharide conjugate vaccine in infants under 2 years old. Methods: From March 2017 to June 2018, 1 932 healthy infants in Biyang County, Henan Province, who were not vaccinated with meningococcal meningitis vaccine and whose axillary temperature was ≤37.0 ℃, were recruited as participants. The 3 months and 6-11 months old infants were allocated to the experiment group and the control group in a ratio of 1∶1. Infants aged 12-23 months were allocated to the 1-dose group, the 2-dose group and the control group in a ratio of 1∶1∶1, with 276 infants in each group. The infants in the experiment group were intramuscularly injected with freeze-dried group A+C meningococcal polysaccharide conjugate vaccine to be evaluated, and infants in the control group received intramuscular injection of commercially available freeze-dried group A+C meningococcal conjugate vaccine. The venous blood of infants was collected 30 days before the first dose and after the last dose of inoculation, and the antibody seroconversion of each group was determined and compared. Results: The completion rate of immunogenicity study was 95.2% (1 839/1 932). Before inoculation, there was no statistical difference in the geometric mean titer and positive rate of group A+C antibodies between the experiment group and the control group in 3 months and 6-11 months old infants (all P values >0.05). The geometric mean titers and positive rate of group A antibodies in the 1-dose group were higher than those in the control group (all P values <0.05), but there was no statistical difference between the 2-dose group and the control group (all P values >0.05) in infants aged 12-23 months. After inoculation, the differences (95%CI) in the positive conversion rate of group A+C antibodies between the experiment group and the control group were -0.12% (-6.01%-5.77%) and 0.82% (-4.23%-5.86%) in the 3 months old infants. At the age of 6-11 months, the differences were 6.75% (1.71%-11.79%) and -4.32% (-8.73%-0.08%), respectively. At the age of 12-23 months, the differences were 1.02% (-3.80%-5.83%) and -4.40% (-7.79%- -1.01%) in the 2-dose group and -7.22% (-12.90%- -1.54%) and -18.61% (-23.75%- -13.46%) in the 1-dose group, respectively. The geometric mean titers of group A+C antibodies in the 3 months old infants were 48.50 and 63.12, respectively, which had no significant difference from the control group (43.02 and 57.99, respectively) (both P values <0.05). The geometric mean titers of group A+C antibodies in the 6-11 months and 12-23 months old infants were 84.09 and 92.51 (2-dose group), which were higher than those in the corresponding control group (43.10 and 61.83, respectively) (all P values <0.001). Conclusion: Group A+C meningococcal conjugate vaccine has good immunogenicity in infants under 2 years old.

First Measurement of High-Energy Reactor Antineutrinos at Daya Bay

This Letter reports the first measurement of high-energy reactor antineutrinos at Daya Bay, with nearly 9000 inverse beta decay candidates in the prompt energy region of 8-12 MeV observed over 1958 days of data collection. A multivariate analysis is used to separate 2500 signal events from background statistically. The hypothesis of no reactor antineutrinos with neutrino energy above 10 MeV is rejected with a significance of 6.2 standard deviations. A 29% antineutrino flux deficit in the prompt energy region of 8-11 MeV is observed compared to a recent model prediction. We provide the unfolded antineutrino spectrum above 7 MeV as a data-based reference for other experiments. This result provides the first direct observation of the production of antineutrinos from several high-Q_{β} isotopes in commercial reactors.

Joint Determination of Reactor Antineutrino Spectra from ^{235}U and ^{239}Pu Fission by Daya Bay and PROSPECT

A joint determination of the reactor antineutrino spectra resulting from the fission of ^{235}U and ^{239}Pu has been carried out by the Daya Bay and PROSPECT Collaborations. This Letter reports the level of consistency of ^{235}U spectrum measurements from the two experiments and presents new results from a joint analysis of both data sets. The measurements are found to be consistent. The combined analysis reduces the degeneracy between the dominant ^{235}U and ^{239}Pu isotopes and improves the uncertainty of the ^{235}U spectral shape to about 3%. The ^{235}U and ^{239}Pu antineutrino energy spectra are unfolded from the jointly deconvolved reactor spectra using the Wiener-SVD unfolding method, providing a data-based reference for other reactor antineutrino experiments and other applications. This is the first measurement of the ^{235}U and ^{239}Pu spectra based on the combination of experiments at low- and highly enriched uranium reactors.

[Comparative study of three scores in predicting the death risk of severe burn patients]

Objective: To explore the predictive values of the modified Baux score, Belgian Outcome in Burn Injury score, and Ryan score on the death risk of severe burn patients. Methods: A retrospective case series study was conducted. From February 2018 to November 2019, 260 severe burn patients who met the inclusion criteria were admitted to the Department of Burns of the First Affiliated Hospital of Nanchang University, including 158 males and 102 females, aged 36 (3, 53) years. According to the final outcome, the patients were divided into survival group (n=229) and death group (n=31). Data of patients were compared and statistically analyzed with chi-square test or Mann-Whitney U test between the two groups, including the gender, age, cause of burn, site of burn, total burn area, depth of burn, combined inhalation injury, and combined underlying diseases on admission, and the modified Baux score, Belgian Outcome in Burn Injury score, and Ryan score calculated based on part of the aforementioned data. The Kendall tau-b coefficient method was used to analyze the consistency of the above-mentioned three scores in 260 severe burn patients. The receiver operating characteristic (ROC) curves of the above-mentioned three scores predicting the death risk of 260 severe burn patients were drawn, and the area under the curve (AUC), the optimal threshold, and the sensitivity and specificity under the optimal threshold were calculated. The quality of AUC of the above-mentioned three scores was compared by Delong test. Results: The gender, site of burn, and depth of burn of patients between the two groups were all similar (P>0.05). The age, total burn area, proportion of flame burn, proportion of combined inhalation injury, and proportion of combined underlying diseases of patients in death group were significantly higher than those in survival group (with Z values of 5.53 and 17.78, respectively, χ2 values of 16.23, 15.89, and 17.78, respectively, P<0.01); the modified Baux score, Belgian Outcome in Burn Injury score, and Ryan score of patients in death group were 142 (115, 155), 7 (5, 7), 2 (2, 3), all significantly higher than 64 (27, 87), 1 (0, 3), 0 (0, 1) in survival group (with Z values of 7.91, 7.64, and 7.61, respectively, P<0.01). In 260 severe burn patients, the results between the modified Baux score and Ryan score, modified Baux score and Belgian Outcome in Burn Injury score, Ryan score and Belgian Outcome in Burn Injury score were significantly consistent (with Kendall tau-b coefficients of 0.75, 0.71, and 0.86, respectively, P<0.01). The AUCs of ROC curves of the modified Baux score, Belgian Outcome in Burn Injury score, and Ryan score for predicting the death risk of 260 severe burn patients were 0.92, 0.89, and 0.85, respectively (with 95% confidence intervals of 0.86-0.98, 0.83-0.95, and 0.78-0.93, respectively, P<0.01); the optimal thresholds were 106.5, 4.5, and 1.5 points, respectively; the sensitivity under the optimal threshold were 88.5%, 76.9%, and 73.1%, respectively, and the specificity under the optimal threshold were 88.5%, 87.2%, and 86.3%, respectively. The modified Baux score was similar to Belgian Outcome in Burn Injury score in the AUC quality (z=1.25, P>0.05), which were both significantly better than the AUC quality of Ryan score (with z values of 2.35 and 2.11, respectively, P<0.05). Conclusions: The modified Baux score, Belgian Outcome in Burn Injury score, and Ryan score have good ability in predicting the death risk of severe burn patients. From the perspective of clinical practice, the modified Baux score is more suitable as a predictive tool for the prognosis of severe burn patients.

Selection and implementation of single nucleotide polymorphism markers for parentage analysis in crossbred cattle population

Crossbreeding is an essential way of improving herd performance. However, frequent parentage record errors appear, which results in the lower accuracy of genetic parameter estimation and genetic evaluation. This study aims to build a single nucleotide polymorphism (SNP) panel with sufficient power for parentage testing in the crossbred population of Simmental and Holstein cattle. The direct sequencing technique in PCR products of pooling DNA along with matrix-assisted laser desorption/ionization time-of-flight MS method for genotyping the individuals was applied. A panel comprising 50 highly informative SNPs for parentage analysis was developed in the crossbred population. The average minor allele frequency for SNPs was 0.43, and the cumulative probability of exclusion for single-parent and both-parent inference met 0.99797 and 0.999999, respectively. The maker-set for parentage verification was then used in a group of 81 trios with aid of the likelihood-based parentage-assignment program of Cervus software. Reconfirmation with on-farm records showed that this 50-SNP system could provide sufficient and reliable information for parentage testing with the parental errors for mother-offspring and sire-offspring being 8.6 and 18.5%, respectively. In conclusion, a set of low-cost and efficient SNPs for the paternity testing in the Simmental and Holstein crossbred population are provided.

[ Ⅲ ]

Objective: The aim of this study was to evaluate the safety and immunogenicity of the first domestic ACYW135 meningococcal conjugate vaccine and a control vaccine named AC group meningococcal conjugate vaccine for 3 months (90-119 days) infants. Methods: From February 2017 to June 2018, a randomized, blinded, and similar vaccine-controlled clinical trial design was adopted at the Henan Vaccine Clinical Research Base. The subjects were 3 months old healthy infants, a total of 720, based on a 1∶1 ratio. The random allocation table for entry was randomly assigned to the experimental group and the control group. According to the 3, 4, and 5 month-old vaccination procedures, the subjects were vaccinated with test vaccine (ACYW135 group meningococcal conjugate vaccine) and control vaccine (group A group C meningococcal polysaccharide conjugate vaccine), of which 720 were given the first dose, 696 were given the second dose (test group: 346; control group: 350), and 692 were given the third dose (test group: 344; Control group: 348). Results: The overall adverse reaction rate of the test vaccine was 21.90% (230 cases), which was lower than the 32.04% (339 cases) of the control vaccine (P<0.001). The incidence of systemic adverse reactions was 19.52% (205 cases), which was lower than that of the control vaccine (27.69%) (293 cases) (P<0.001). The local adverse reaction rate was 3.04% (32 cases), which was lower than the control group (7.84%) (83 cases) (P<0.001). The graded adverse reaction test vaccine was 0.57% (6 cases), which was lower than the control group of 2.36% (25 cases) (P<0.001). The positive conversion rate of anti-bacterial serum antibodies showed that there was no significant difference between the test vaccine group A (91.42%), C (88.76%) and the control vaccine (92.92%) (87.02%) (P>0.05). Group Y and W135 was 88.17% (298 cases), 99.41% (336 cases), respectively. The GMT results showed that the test vaccine group A was 56.24, the control vaccine was 57.43 (P>0.05); the group C test vaccine (43.53) was higher than the control group (27.28) (P<0.001). The group Y and W135 are 89.22 and 140.66, respectively. Among them, the proportion of the group C GMT antibody ≥ 1∶128 for test vaccine (31.07%, 105 cases) was higher than the control vaccine (16.22%, 55 cases) (P<0.001). Conclusion: ACYW135 group meningococcal conjugate vaccine has more safety and immunogenicity after application to 3 month old infants.

Improved Constraints on Sterile Neutrino Mixing from Disappearance Searches in the MINOS, MINOS+, Daya Bay, and Bugey-3 Experiments

Searches for electron antineutrino, muon neutrino, and muon antineutrino disappearance driven by sterile neutrino mixing have been carried out by the Daya Bay and MINOS+ collaborations. This Letter presents the combined results of these searches, along with exclusion results from the Bugey-3 reactor experiment, framed in a minimally extended four-neutrino scenario. Significantly improved constraints on the θ_{μe} mixing angle are derived that constitute the most constraining limits to date over five orders of magnitude in the mass-squared splitting Δm_{41}^{2}, excluding the 90% C.L. sterile-neutrino parameter space allowed by the LSND and MiniBooNE observations at 90% CL_{s} for Δm_{41}^{2}<13  eV^{2}. Furthermore, the LSND and MiniBooNE 99% C.L. allowed regions are excluded at 99% CL_{s} for Δm_{41}^{2}<1.6 eV^{2}.

[The etiological and molecular typing research of diarrheagenic Escherichia coli in Henan province in 2013]

OBJECTIVE

To analyze the distribution and pulsed field gel electrophoresis (PFGE) patterns of five kinds of diarrheagenic Escherichia coli (DEC) in infected diarrhea population of Henan province in 2013.

METHODS

Gathering 1 037 strains of E. coli of 1 037 diarrhea patients from four sentinel hospitals of multi-pathogen monitoring system in Henan province in 2013. Stool samples were cultured with Mac agar plates and using KIA/MIU biochemical action as the preliminary method to identify E. coli strains; preparation of DNA template with thermal cracking method and using multiplex PCR to detect five kinds of DEC. According to molecular typing method published by the international PulseNet bacterial infectious disease monitoring network, the PFGE molecular characteristics of DEC strains were analyzed.

RESULTS

125 DEC positive strains were detected in 1 037 strains of E. coli, the total detection rate was 12.05%. 90 strains were enteroaggregative E.coli (EAEC), detection rate was 8.68% (n=90); 24 strains were enteropathogenic E.coli (EPEC), detection rate was 2.31%; 7 strains were enteroinvasive E.coli (EIEC), detection rate was 0.68%; 4 strains were enterotoxigenic E.coli (ETEC), detection rate was 0.39%; enterohemorrhagic E.coli (EHEC) was not detected. 639 cases of diarrhea samples were collected from male patients, 398 cases were from female patients, 94 positive cases were from male patients, the detection rate was 14.71%.The positive number of female cases were 31 cases, the detection rate was 7.79%. 97 positive cases were detected from 782 countryside cases and 28 positive cases were detected from 255 urban area cases, with detection rate 12.40% and 10.98% respectively. In 125 cases of DEC positive samples, children below 5 years old were 83 cases, accounting for 66.4%; 53 strains of EAEC were divided into 52 molecular patterns by digestion with XbaⅠ and pulsed field gel electrophoresis, each pattern contained 1-2 strains with similarity ranged from 66.3%-100%; 18 strains of EPEC were divided into 18 molecular patterns, each pattern contains 1 strain with similarity ranged from 72.6%-94.8%; 5 strains of EIEC were divided into 5 molecular patterns, each pattern contains 1 strain with similarity ranged from 71.9%-98.5%. 2 strains of ETEC were divided into 2 molecular patterns and similarity below 70%.

CONCLUSION

Through the research we could find that four kinds of DEC as a pathogenic bacteria took an important component in pathogenic spectrum of bacterial diarrhea of Henan province in 2013. Four kinds of DEC carrying different virulence genes and taking multiple PFGE patterns showed diversity and complexity characteristics.

Physiological integration enhanced the tolerance of Cynodon dactylon to flooding

Many flooding-tolerant species are clonal plants; however, the effects of physiological integration on plant responses to flooding have received limited attention. We hypothesise that flooding can trigger changes in metabolism of carbohydrates and ROS (reactive oxygen species) in clonal plants, and that physiological integration can ameliorate the adverse effects of stress, subsequently restoring the growth of flooded ramets. In the present study, we conducted a factorial experiment combining flooding to apical ramets and stolon severing (preventing physiological integration) between apical and basal ramets of Cynodon dactylon, which is a stoloniferous perennial grass with considerable flooding tolerance. Flooding-induced responses including decreased root biomass, accumulation of soluble sugar and starch, as well as increased activity of superoxide dismutase (SOD) and ascorbate peroxidase (APX) in apical ramets. Physiological integration relieved growth inhibition, carbohydrate accumulation and induction of antioxidant enzyme activity in stressed ramets, as expected, without any observable cost in unstressed ramets. We speculate that relief of flooding stress in clonal plants may rely on oxidising power and electron acceptors transferred between ramets through physiological integration.

Accuracy improvement of quantitative analysis by spatial confinement in laser-induced breakdown spectroscopy

To improve the accuracy of quantitative analysis in laser-induced breakdown spectroscopy, the plasma produced by a Nd:YAG laser from steel targets was confined by a cavity. A number of elements with low concentrations, such as vanadium (V), chromium (Cr), and manganese (Mn), in the steel samples were investigated. After the optimization of the cavity dimension and laser fluence, significant enhancement factors of 4.2, 3.1, and 2.87 in the emission intensity of V, Cr, and Mn lines, respectively, were achieved at a laser fluence of 42.9 J/cm(2) using a hemispherical cavity (diameter: 5 mm). More importantly, the correlation coefficient of the V I 440.85/Fe I 438.35 nm was increased from 0.946 (without the cavity) to 0.981 (with the cavity); and similar results for Cr I 425.43/Fe I 425.08 nm and Mn I 476.64/Fe I 492.05 nm were also obtained. Therefore, it was demonstrated that the accuracy of quantitative analysis with low concentration elements in steel samples was improved, because the plasma became uniform with spatial confinement. The results of this study provide a new pathway for improving the accuracy of quantitative analysis of LIBS.

Stress and phase purity analyses of diamond films deposited through laser-assisted combustion synthesis

Diamond films were deposited on silicon and tungsten carbide substrates in open air through laser-assisted combustion synthesis. Laser-induced resonant excitation of ethylene molecules was achieved in the combustion process to promote diamond growth rate. In addition to microstructure study by scanning electron microscopy, Raman spectroscopy was used to analyze the phase purity and residual stress of the diamond films. High-purity diamond films were obtained through laser-assisted combustion synthesis. The levels of residual stress were in agreement with corresponding thermal expansion coefficients of diamond, silicon, and tungsten carbide. Diamond-film purity increases while residual stress decreases with an increasing film thickness. Diamond films deposited on silicon substrates exhibit higher purity and lower residual stress than those deposited on tungsten carbide substrates.

Fast growth of branched nickel monosilicide nanowires by laser-assisted chemical vapor deposition

Branched nickel monosilicide (NiSi) nanowires (NWs), for the first time, have been synthesized on Ni foams by laser-assisted chemical vapor deposition using disilane precursor molecules. Studies indicate that 600 °C is the threshold temperature for the growth of a large number of branched NiSi NWs with 100-500 nm long branches extending from the main stems. Below the threshold temperature, unbranched NiSi NWs were obtained. The density of the branched NiSi NWs is relatively higher in comparison to that of the unbranched ones. The growth rate of the branched NiSi NWs at 700 °C is estimated up to 10 µm min(-1). High-resolution transmission electron microscopy and energy-dispersive x-ray spectroscopy of the branched NiSi NWs suggest that the formation of these branched nanostructures is ascribed to the Ni-dominant diffusion process. These NiSi NWs with branched nanostructures could bring them new opportunities in nanodevices.

Spectroscopic determination of rotational temperature in C2H4/C2H2/O2 flames for diamond growth with and without tunable CO2 laser excitation

Optical emission spectroscopy (OES) and spectroscopic temperature determination were carried out to study C(2)H(4)/C(2)H(2)/O(2) flames used for diamond deposition with and without an excitation by a wavelength-tunable CO(2) laser. Strong emissions from C(2) and CH radicals were observed in the visible range in all the acquired OES spectra. When the flames were irradiated by using a continuous-wave (CW) CO(2) laser at a wavelength of 10.591 microm, the emission intensities of the C(2) and CH radicals in the flames increased owing to the laser excitation. The CO(2) laser was also tuned to a wavelength of 10.532 microm to precisely match the resonant frequency of the CH(2)-wagging vibrational mode of the C(2)H(4) molecules. OES spectroscopy of the C(2) and CH radicals were performed at different laser powers. The rotational temperatures of CH radicals in the flames were determined by analyzing the spectra of the R branch of the A(2)Delta-->X(2)Pi (0,0) electronic transition near 430 nm. The deposited diamond thin-films were characterized by scanning electron microscopy, stylus profilometry, and Raman spectroscopy. The deposition mechanism with and without the CO(2) laser excitation was discussed based on the OES spectral results.

Detection of trace phosphorus in steel using laser-induced breakdown spectroscopy combined with laser-induced fluorescence

Monitoring of light-element concentration in steel is very important for quality assurance in the steel industry. In this work, detection in open air of trace phosphorus (P) in steel using laser-induced breakdown spectroscopy (LIBS) combined with laser-induced fluorescence (LIF) has been investigated. An optical parametric oscillator wavelength-tunable laser was used to resonantly excite the P atoms within plasma plumes generated by a Q-switched Nd:YAG laser. A set of steel samples with P concentrations from 3.9 to 720 parts in 10(6) (ppm) were analyzed using LIBS-LIF at wavelengths of 253.40 and 253.56 nm for resonant excitation of P atoms and fluorescence lines at wavelengths of 213.55 and 213.62 nm. The calibration curves were measured to determine the limit of detection for P in steel, which is estimated to be around 0.7 ppm. The results demonstrate the potential of LIBS-LIF to meet the requirements for on-line analyses in open air in the steel industry.

Association and activation of fructose 1,6-bisphosphase during unfolding and refolding: spectroscopic and enzymatic studies

Fructose 1,6-biphosphase is a well-characterized oligomer enzyme, and many effectors allosterically control its activity. In this report, we compared the activity, allosteric properties, and conformational changes in its denaturant-induced unfolding processes. In addition, a trpytophan residue has been introduced into the interface between the C1 and C2 subunits to investigate conformational changes during unfolding. Results show that the denaturation curves of WT FruP2ase detected by various methods do not agree, and the dissociation occurs first with a monomeric form existing around 0.4 M GdmCl as shown by gel filtration. The dissociation of all mutants is accompanied by changes in fluorescence intensity. The results suggest that the unfolding of FruP2ase is a complicated, multiphase process. The activation of FruP2ase by GdmCl at low concentrations can be interpreted as a consequence of the effect of monovalent cation. In the refolding experiments, it is found that Mg2+ is not only essential for enzyme activity, but also can assist the enzyme in refolding and association by preventing the formation of aggregates.

Effects of vasoactive intestinal polypeptide antagonists on cholinergic neurotransmission in dog and cat trachea

1. The effects of vasoactive intestinal polypeptide (VIP) antagonists [AC-Tyr1, D-Phe2]-GRF(1-29)-NH2 and [4-Cl-D-Phe6, Leu17]-VIP on excitatory neuroeffector transmission in the dog and cat trachea were investigated by use of microelectrode, double sucrose-gap and tension recording methods. 2. In the dog trachea, repetitive stimuli at high frequency (20 Hz) markedly enhanced the amplitude of contraction, the amplitude of contractions evoked by 50 stimuli at 20 Hz relative to that evoked by 5 stimuli being 14.2 +/- 3.8 times (n = 7, +/- s.d.). In the cat, the summation was much less marked, the amplitude of contractions evoked by 50 stimuli relative to that evoked by 5 stimuli being only 2.1 +/- 0.6 times (n = 5, +/- s.d.). Neither VIP antagonist had any effect on the relationship between the number of stimuli at 20 Hz and the relative amplitude of contraction in the dog trachea, but did enhance the amplitude of contractions to 1.1-1.5 times control in the cat trachea. 3. VIP antagonists dose-dependently enhanced the amplitude of excitatory junction potentials (e.j.ps) evoked by a single stimulus in the cat trachea, without changing the resting membrane potential or input membrane resistance of the smooth muscle cells. However, neither antagonist had any effect on the amplitude of the e.j.p. in the dog trachea. 4. Neither VIP antagonist had any effect on the post-junctional response of smooth muscle cells to exogenously applied acetylcholine (ACh; 10(-9)-10(-5) M) in the dog or cat trachea.5. In the cat trachea, VIP (10-11 M) suppressed the ej.p. amplitude to 0.74 +/- 0.09 times the control value (n = 6). However, after pretreatment of the tissue with the VIP antagonists [Ac-Tyr', D-Phe2]-GRF(1-29)- H2 (10-8M) and [4-Cl-D-Phe6, Leu17]-VIP (10-8M), VIP (10-11 M) did not suppress the ej.p. amplitude, indicating that VIP antagonists block the presynaptic inhibitory action of exogenous VIP.6. In parallel with the enhancement of contraction, ej.ps showed marked summation when repetitive field stimulations were applied at high frequency (20 Hz) in the dog trachea. The relationship between the relative amplitude of the ej.p. and number of stimuli at 20 Hz was linear and the slope was 2.2 +/- 0.3 mV/stimulation. VIP antagonists did not affect this relationship. However, in the cat trachea, summation of ej.ps was not at all marked and a linear relationship was not observed with the double sucrose-gap method. Incubation of the cat tracheal tissue with either of the VIP antagonists (10-8 or 10-7M) markedly enhanced the summation of ej.ps evoked by repetitive field stimulation at 20 Hz, and after the treatment a linear relationship between the number of stimuli and the amplitude of ej.ps was observed, the slopes being 0.6 +/- 0.1 (n = 8) and 0.55 +/- 0.1 mV/stimulation (n = 5), respectively.7. These results indicate that both VIP antagonists, [Ac-Tyr', D-Phe2]-GRF(1-29)-NH2 and [4-Cl-DPhe6, Leu17]-VIP, have a prejunctional action accelerating the excitatory neuroeffector transmission, presumably by enhancing transmitter release from the vagus nerves in the cat, but not in the dog trachea.

Effects of immunization against VIP on neurotransmission in cat trachea

To examine the possible role of vasoactive intestinal polypeptide (VIP) in excitatory and inhibitory neurotransmission and physiological function of coexistence VIP and acetylcholine at vagus nerve terminals in the cat trachea, we immunized five cats each against conjugate of VIP-bovine serum albumin (BSA) and BSA, respectively. A booster injection of VIP-BSA given 3 wk after the primary one elevated antibodies against VIP, as detected by enzyme-linked immunosorbent assay, but not in the control cats identically injected with BSA. After immunization, in vitro, summation phenomena observed in the amplitude of contractions and excitatory junction potentials of the trachea evoked by repetitive field stimulation were markedly enhanced, whereas the amplitude of phasic relaxation evoked by repetitive field stimulation in the presence of serotonin, atropine, and guanethidine was markedly reduced. In contrast, in vivo, the change in pulmonary resistance evoked by vagal stimulation was not affected in the immunized cats. We conclude that antibodies against neurotransmitter VIP are a potential modulatory factor in excitatory and inhibitory neurotransmission in airway smooth muscle at tissue or cellular levels. The lack of correlation between in vivo and in vitro conditions was discussed in relation to VIP autoantibodies in normal and asthmatic humans.

Cytogenetic analysis in workers occupationally exposed to nickel carbonyl

Chromosomal aberration and sister-chromatid exchange (SCE) base-line frequencies and SCE frequencies induced by 10 ng/ml mitomycin C (MMC) were analysed in cultured peripheral lymphocytes of 65 workers occupationally exposed to nickel carbonyl Ni(CO)4. The subjects were divided into 4 groups: (1) control; (2) exposed to nickel carbonyl (= exposed); (3) cigarette smokers; (4) smoking-exposed. The results show that there are no significant differences in chromosomal aberration frequencies, breaks or gaps, between the various groups. However, the SCE base-line frequency of the smoking-exposed group, with an average of 7.7/cell, was significantly higher than that of the control group, with an average of 6.5/cell (P less than 0.01), and also than that of the exposed group with an average of 5.9/cell (P less than 0.01). Similarly, the SCE frequency induced by 10 ng/ml MMC in the smoking-exposed group which averaged 15.5/cell was significantly higher than that of the control group (average of 13.2/cell (P less than 0.05], and also than that of the exposed group with an average of 12.3/cell (P less than 0.01). Under our experimental conditions, it may be that the level of exposure was not high enough to elicit an increase in chromosomal aberrations and SCE frequencies in the non-smoker exposed group. The fact that an increase in SCE frequencies was only found in the smoking-exposed group implies that the two factors, smoking and exposure to nickel carbonyl, are jointly responsible for the result.