Bifurcations and chaos control in a discrete Rosenzweig-Macarthur prey-predator model

In this paper, we explore the local dynamics, chaos, and bifurcations of a discrete Rosenzweig-Macarthur prey-predator model. More specifically, we explore local dynamical characteristics at equilibrium solutions of the discrete model. The existence of bifurcations at equilibrium solutions is also studied, and that at semitrivial and trivial equilibrium solutions, the model does not undergo flip bifurcation, but at positive equilibrium solutions, it undergoes flip and Neimark-Sacker bifurcations when parameters go through certain curves. Fold bifurcation does not exist at positive equilibrium, and we have studied these bifurcations by the center manifold theorem and bifurcation theory. We also studied chaos by the feedback control method. The theoretical results are confirmed numerically.

Distribution, screening and biochemical characterization of indigenous microalgae for bio-mass and bio-energy production potential from three districts of Pakistan

Abstract Trend of biofuel production from microalgal triacylglycerols is enhancing, because this substrate is a good sustainable and advantageous alternative to oil and gas fuel. In the present study, indigenous micro algal isolates were screened from water (n=30) and soil (n=30) samples collected from three districts of Punjab, Pakistan to evaluate their biofuel production potential. The samples were inoculated on BG – 11 agar medium plates by incubating at room temperature of 25°C providing 1000 lux for 16h light cycle followed by 8h of dark cycle for 15 d. Water samples were found to be rich in microalgae and 65.33% microalgae (49 isolates) were isolated from Faisalabad district. On the basis of microscopic morphology microalgal isolates (n=180) were selected and subjected to lipid detection by Nile red staining assay. Nile red positive isolates (n=23) were processed for biochemical (lipid, protein and carbohydrates) characterization. AIN63 isolate showed higher lipids (17.4%) content as detected by micro vanillin assay. Algal isolate AIN128 showed best protein contents (42.91%) detected by Bradford assay and AIN172 isolate showed higher carbohydrate contents (73.83%) as detected by anthrone assay. The selected algal isolates were also analyzed by Fourier transform infrared (FTIR) spectroscopy for confirmation of carbohydrate, protein and lipid analysis. These indigenous algae have the potential for in-vitro biofuel production from agricultural waste.

Environmental higher education-renewable energy consumption nexus in China: pathways toward carbon neutrality

Pro-environmental behavior has a significant role to play in environmental sustainability. There has been little research done on environmental higher education-renewable energy consumption nexus. This study examines the impact of environmental higher education on renewable energy consumption in China from 1997 to 2021. The ARDL results show that higher environmental education enhances renewable energy consumption in long run. Findings also show that internet usage and economic development encourage renewable energy consumption in the long run. However, financial development and internet usage have a short-term impact on renewable energy consumption in China. The QARDL estimates are robust, and the finding shows that environmental higher education has a positive impact on renewable energy consumption in short and long run at higher quantiles. The empirical findings have environmental implications for China in terms of achieving long-term environmental sustainability by embracing patterns of pro-environmental behavior.

Enhanced Ferroelectric and Dielectric Properties of Niobium-Doped Lead-Free Piezoceramics

Lead-free ceramics are promising candidates for replacing lead-based piezoelectric materials such as lead-zirconate-titanate (PZT) if they can compete in dielectric and ferroelectric characteristics. In this work, for lead-free piezoelectric ceramic, 0.74(Bi_0.5Na_0.5TiO₃)-0.26(SrTiO₃) (BNT-ST26) and niobium-substituted (Nb-BNT-ST26) ceramics were synthesized by solid-state reactions. The evolution of niobium substitution to the perovskite phase structure of BNT-ST26 ceramics was confirmed by X-ray diffraction (XRD) analysis and Raman spectra. Electromechanical properties of Nb-BNT-ST26 ceramics initially increased with the addition of niobium up to 0.5% and decreased with a further increase in Nb content. Temperature-dependent dielectric curves showed that the depolarization temperature (T_d) decreased below room temperature because of Nb substitution. The composition with 0.5% Nb yielded a maximum bipolar strain (S_max) of 0.265% and normalized strain of d₃₃* ~ 576 pm/V under an electric field of 4.6 kV/mm at room temperature. At this critical concentration of 0.5% Nb, maximum saturation polarization of 26 μC/cm² was achieved. The dielectric constant with temperature peaks became more diffused and the depolarization temperature decreased with the increasing Nb content. The study concludes that Nb-doped BNT-ST26 is an excellent material for high-temperature, stable, frequency-dependent, lead-free piezoelectric devices.

Does educated labor force is managing the green economy in BRCS? Fresh evidence from NARDL-PMG approach

It is observed that an educated labor force can increase the absorption capacity of the economy and improve the effectiveness of green technologies that lead to a reduction in potential CO2 emissions. The study investigates whether an educated labor force contributes to the management of the green economy or not in BRCS economies. Panel ARDL-PMG and NARDL-PMG approaches have been employed for empirical analysis for data ranging from 1995 to 2019. According to the ARDL-PMG results, a highly educated labor force contributes to alleviating CO2 emissions in the long run. In contrast, the findings of NARDL-PMG infer that positive component of a highly educated labor force has a significant negative impact on CO2 emissions, while negative component of a highly educated labor force has a positive impact on CO2 emissions in the long run. The study suggests that BRCS countries' policymakers should promote education and training for the labor force to maintain a reduction in CO2 emissions.

Prevalence of gastrointestinal parasitic infection in cows and buffaloes in Lower Dir, Khyber Pakhtunkhwa, Pakistan

Gastrointestinal (GI) Parasitic infection is a hot issue for cattle management. There is variation of GI parasites effects in sex, age of cattle, drinking water condition, nutrition, and severity of infection. Studies on prevalence of GI parasites among cattle population in Dir Lower are lacking. A total of 40 farms were selected randomly in six tehsil namely Tehsil Adenzai, Tehsil Timergara, Tehsil Balambat, Tehsil Munda ,Tehsil Lalqala, Tehsil Khall. Freshly cattle fecal samples were collected randomly from the selected farms during March 2018 till December 2018. Out of 314 buffaloes and cattle examined 58.59% (184/314) were positive for eggs, cyst/oocyst of one or more species of GI Parasites. The prevalence of parasitic infection was higher in Buffaloes 63.55% (75/118) as compared to Cow 55.61% (109/196) but the difference was not significant (p>0.05) Entamoeba,spp, Moniezia spp, Haemonchus spp and Coccidian spp were found in this study. The non-treated animals indicated the highest percentage of infection in cow 57.71% (101/175) and buffalo 68.13% (62/91).GI parasite prevalence in female animal were higher female cow 62.58% (87/139) and female buffalo 77.33% (58/75) as compared to male. But the difference is non-significant (p> 0.05) Yearling calves had the lower rate of GI parasitic infection than adults. Future investigations are necessary to evaluate the economic loss due to GI parasites in cattle's.

Exploring the asymmetric effects of renewable energy production, natural resources, and economic progress on CO2 emissions: fresh evidence from Pakistan

A bulk of literature has examined the asymmetric impact of renewable energy consumption on CO₂ emissions by using the advanced econometric approach. While the asymmetric role of renewable energy production in the CO₂ equation is largely unknown, our present study quantifies the asymmetric relationship between renewable energy production, natural resources, economic progress, and CO₂ emission for Pakistan by using the NARDL approach. It is found that positive change in renewable energy production has a positive effect on CO₂ emissions, while a negative change in renewable energy production has a negative effect on CO₂ emissions in the long run. Furthermore, a positive and negative change in natural resources contributes negatively to CO₂ emissions in the long run. The results reveal that a positive change in economic progress significantly increases CO₂ emissions in the long run. Based on findings, Pakistan's government should encourage local and international investors to increase their investment in the production of renewable energy by reducing environmental degradation.

Analysis of income inequality and environmental pollution in BRICS using fresh asymmetric approach

With rapid economic growth, BRICS is facing enormous burdens of carbon emission and severe issues of income inequality. However, behind this economic success, the BRICS economies also face few thoughtful challenges to improve environmental quality by catching up the sustainable development goals. Consequently, the existing empirical research is concerned with the dynamic links between income inequality and CO₂ emissions by using the novel nonlinear ARDL approach, but small attention has been paid to the BRICS in literature. Therefore, we observed that a negative and positive change in income inequality has positive effect on CO₂ emissions in Russia and South Africa in the long run, although a positive change in income inequality has positive effects on CO₂ emissions in Brazil, Russia, and China, while a negative change in income inequality has negative effect on CO₂ emissions in India, Brazil, and Russia in the short run. Hence, the findings value specific attention from policymakers in BRICS economies.

The trade-off between economic growth and environmental quality: does economic freedom asymmetric matter for Pakistan?

This empirical study investigates the dynamic effects of economic freedom on economic growth and air quality for Pakistan over the period 1990-2019. The ARDL results suggest that economic freedom and other variables do not have any visible impact on economic growth and pollution in the short-run. However, in the long-run, economic freedom significantly mitigates air pollution whereas inflation instability increases emissions. The NARDL results show that a partial sum of positive change in economic freedom is negatively linked with economic growth in the short term but has positive effect in the long term. However, the negative change in economic freedom has negative but insignificant impact on growth confirming asymmetric effects. The results for the pollution model show that a partial sum of positive change in economic freedom has positive impact on emissions both in the short and long-runs, whereas a negative change has no significant effect in the short-run and has negative impact in the long-run. Thus, economic freedom supports economic activities that, in turn, escalate emissions in the atmosphere.

The nexus of sectoral-based CO2 emissions and fiscal policy instruments in the light of Belt and Road Initiative

Climate change due to global warming is becoming a major global issue over the past few decades. The emission of carbon dioxide (CO2) and other greenhouse gasses cause global warming. Most carbon emissions come from energy sectors, whereas transportation, industrial, and residential sectors are among the chief contributors. The present study investigates the effect of fiscal policy instruments, economic development, and foreign direct investment (FDI) on the sectoral emissions in Belt and Road Initiative (BRI) countries. The data used in this study is taken from the World Development Indicators (WDI) for the period between 2000 and 2018. Dynamic ordinary least squares (DOLS) and fully modified ordinary least squares (FMOLS) have been used to analyze the long-run impact of fiscal policy instruments, economic development, and FDI on CO2 emissions from transportation, energy, and industrial sectors. Furthermore, the pairwise Dumitrescu and Hurlin panel causality test was used to authorize the causal relationship among the variables under consideration. The results reveal that fiscal policy instruments, per capita gross domestic product, FDI, and CO2 emissions show a strong correlation in the industrial, electrical, and transportation sectors. Furthermore, it is shown that public spending is a more reliable tool to reduce CO2 emissions in the transportation and industrial sectors in the BRI region. This study provides useful information for policy-makers on taking preventive and corrective measures to reduce CO2 emissions in different sectors and promote sustainable development.

Assessment of ecto and endo parasites of Schizothorax plagiostomus inhabiting river Panjkora, Khyber Pakhtunkhwa, Pakistan

Fish provides main source of high quality protein to more than one billion people in the world. Fish parasites directly affect the productivity of fish and indirectly on human health. This research was aimed to assess the helminth parasites in Schizothorax plagiostomus (the snow trout) from river Panjkora, KP, Pakistan. A total of 88 fish samples (n= 88) were collected from the upper, middle and lower regions of the river through cast nets, hand nets and hooks. All the collected fish samples were examined in the Parasitology Laboratory, Department of Zoology, University of Malakand for helminth parasites during July 2018 to February 2019.Among these fishes nematodes, trematodes, cestodes and acanthocephalan were isolated and identified. Overall prevalence of the fish parasites was 60.22% (53/88). The intensity of the parasite was observed from 1.7% to 4.61%. Highest prevalence was reported in summer season 86.36% while lowest in the winter season 36.36%. This study shows that summer season affects the fish business and result in poor quality fish meat with risk of zoonotic diseases. Adults were highly infected 82.25% while no infection was found in juvenile specimens. Female fish samples had higher prevalence 68.22% than males 48.22%. Fishes of the lower reaches had highest prevalence 60.22% than the upper reaches 40.0%. Fish samples with maximum length and weight were highly 76.92% infected than small sized fish with low body weight. Present study addresses that Rhabdochona schizothoracis in the intestine and Diplozoon paradoxum in gills of snow trout fish has a long term relationship and call as a natural infection in cyprinids and it is zoonotic threat to human.

Evaluation of ecto and endo parasitic fauna of Schizothorax plagiostomus inhabitants of river Swat, Khyber PakhtunKhwa, Pakistan

Fish is consumed as a rich and cheaper source of white meat and proteins all over the world. Fish farming is the leading source of income generation throughout the world. The present research study was conducted with aims to investigate the ecto and endo parasitic fauna of S. plagiostomus (snow trout) in River Swat. A total of 96 fish samples were collected on monthly basis from July-2018 to February-2019, from upper, middle and lower reaches. Fish samples were collected with the help of cast net, hand net and fishing rods. Local fishermen and experts help were also sought out for fish collection. 61 out of 96 fishes were found infected by helminth parasites. The total prevalence and intensity of 63.54% and 2.90 was observed respectively during data analysis. Highest monthly prevalence of 83.33% was recorded during July and August, while lowest prevalence of 33.33% was noted during February. Five species of helminths parasites were detected from S. plagiostomus, of which two were trematodes (Rhabdochona shizothoracis and Rhabdochona species), one species of Monogenia (Diplozoon paraddoxum), one species of Cestodes (Nippotaenia species), and one species of Acanthocephalan (Neoechynorhynchus devdevi). Highest parasite wise prevalence, intensity and relative density of 21.87%, 4.09 and 0.895 was noted for R. schizothoracis while the lowest prevalence, intensity and relative density of 4.16%, 1.25 and 0.052 was noted for N. devdevi. Highest infection of 76.08% was observed in adults host while lowest, 40% infestation rate was observed in young fish samples. 73.68% prevalence was observed in female hosts while only 56.90% prevalence was observed in male individuals. Higher infection (83.33%) was noticed during summer season, while lowest infection (44.44%) was observed during winter season. Similarly 71.79% fishes were found infected that were collected from lower reaches of the River Swat than the fish samples collected from upper reaches (52%).

Revealing the Effects of Microarc Oxidation on the Mechanical and Degradation Properties of Mg-Based Biodegradable Composites

To overcome the inherent weakness of polylactic acid (PLA), used as scaffolding materials, multiple samples of Mg/PLA alloy composite materials was made by plastic injection molding. To enhance the interfacial interaction with PLA, magnesium alloy was treated with microarc oxidation (MAO) at four different frequencies, resulting in an improvement in mechanical strength and toughness. The microarc oxidation films consisted mainly of a porous MgO ceramic layer on the Mg rod. Based on the phenomenon of micro-anchoring and electrostatic interaction, a change in frequency during MAO showed considerable improvements in the ductility of the composite materials. The presence of the ceramic layer enriched the interfacial bonding between the Mg rod and outer PLA cladding, resulting in the PLA-clad Mg rod showing a higher tensile strength. In vitro degradation test was carried out in Hank's solution for different time periods. Surface-treated Mg alloy-based composite samples displayed a lower degradation rate as compared to untreated Mg alloy samples. The surface-treated sample at a 800 Hz pulse frequency showed the best degradation resistance and mechanical properties after being immersed in Hank's solution as compared to other samples. Mg-reinforced PLA composite rods are promising candidates for orthopedic implants.

Contemplating the Impact of the Moderators Agency Cost and Number of Supervisors on Corporate Sustainability Under the Aegis of a Cognitive CEO

The social cognitive theory emphasizes the risk-taking behavior of an entrepreneur, which leads him to make the right decisions. In this regard, this study formulates the concept of the cognitive CEO through the DAE statistical technique. Specifically, CEO attributes such as CEO age, CEO compensation, CEO tenure, goodwill, and the number of CEO-attended meetings are used as inputs that influence the intangible assets, the output. Chinese SMEs have been selected for empirical analysis for the years 2014-2018. The empirical results reveal that having a cognitive CEO augmented corporate sustainability, while agency cost and the number of supervisors strongly diminished corporate sustainability. Meanwhile, high earnings per share and high total assets are vehicles for maintaining the sustainable growth of firms. Additionally, it is indicated that firms with a loan burden cannot maintain sustainable corporate growth. Lastly, the execution of 2SLS and GMM instrumental regressions authenticate the veracity of results.

Revealing of Core Shell Effect on Frequency-Dependent Properties of Bi-based Relaxor/Ferroelectric Ceramic Composites

In this study, electromechanical characteristics of (1-x) Bi_0.5Na_0.5TiO₃–xSrTiO₃ (ST26, x = 0.26)/(1-y) Bi_0.5Na_0.5TiO₃–ySrTiO₃ (ST10, y = 0.1) (matrix/seed) composites were studied. The ST26 (high relaxor phase) and ST10 (a relaxor ferroelectric (RF), high ferroelectric phase) composite with large (r-ST26-ST10) and small (t-ST26-ST10) grains exhibited frequency-related dielectric properties and large strain response at a low triggering electric field (an incipient piezoelectricity). It is ascribed to a matrix-seed effect originating from the inhomogeneous composition due to the presence of two phases. The r-ST26-ST10 composite sintered at 4 h, prominent material, showed a high normalized dynamic strain (d₃₃*) of ~700 pm/V (large grains) with stable frequency dependence properties at a low field of 40 kV/cm. The properties of the r-ST26-ST10 composite exhibit less decay with frequency-related polarization and strain compared to those of t-ST26-ST10 composite. The increase in soaking time promotes the diffusion and homogenization of the microstructure in composites, leading to changes in the core-shell structure in the solid solution. The polarization and strain of the ST26-ST10 composites with the frequency are linked to the stability of the internal random fields created by non-ergodic relaxor phase of seed and the amount of phase change in the ergodic relaxor matrix.

Structural basis of pathogen recognition by an integrated HMA domain in a plant NLR immune receptor

Plants have evolved intracellular immune receptors to detect pathogen proteins known as effectors. How these immune receptors detect effectors remains poorly understood. Here we describe the structural basis for direct recognition of AVR-Pik, an effector from the rice blast pathogen, by the rice intracellular NLR immune receptor Pik. AVR-PikD binds a dimer of the Pikp-1 HMA integrated domain with nanomolar affinity. The crystal structure of the Pikp-HMA/AVR-PikD complex enabled design of mutations to alter protein interaction in yeast and in vitro, and perturb effector-mediated response both in a rice cultivar containing Pikp and upon expression of AVR-PikD and Pikp in the model plant Nicotiana benthamiana. These data reveal the molecular details of a recognition event, mediated by a novel integrated domain in an NLR, which initiates a plant immune response and resistance to rice blast disease. Such studies underpin novel opportunities for engineering disease resistance to plant pathogens in staple food crops.

Structure–property relationship in lead-free A- and B-site co-doped Bi0.5(Na0.84K0.16)0.5TiO3–SrTiO3 incipient piezoceramics

A phase diagram of A- and B-site co-substituted lead-free incipient piezoceramics is schematically constructed on the basis of crystal structure and electromechanical, dielectric and piezoelectric properties.

Correction: Structure–property relationship in lead-free A- and B-site co-doped Bi0.5(Na0.84K0.16)0.5TiO3–SrTiO3 incipient piezoceramics

Correction for ‘Structure–property relationship in lead-free A- and B-site co-doped Bi_0.5(Na_0.84K_0.16)_0.5TiO₃–SrTiO₃ incipient piezoceramics’ by Rizwan Ahmed Malik et al., RSC Adv., 2015, 5, 96953–96964.

Changes in oestrogen receptor alpha expression in the nucleus of the solitary tract of the rat over the oestrous cycle and following ovariectomy

Oestrogen is capable of modulating autonomic outflow and baroreflex function via actions on groups of neurones in the brainstem. We investigated the presence of oestrogen receptor (ER) alpha in a part of the nucleus of the solitary tract (NTS) associated with central cardiovascular control, aiming to determine whether ERalpha mRNA and protein expression is correlated with levels of circulating oestrogen during the oestrous cycle. Polymerase chain reaction (PCR) detected ERalpha mRNA in the NTS at each stage of the oestrous cycle, from ovariectomised, sham-operated and male rats. Real-time PCR showed variations in ERalpha mRNA expression during the oestrous cycle, with the highest levels seen in oestrus, and lowest levels in metoestrus (P < 0.05 versus oestrus) and proestrus (P < 0.05 versus oestrus). Expression in males was lower than in dioestrus and oestrus females (P < 0.05). After ovariectomy, ERalpha mRNA levels were decreased compared to sham-operated animals (P < 0.01). Confocal fluorescence immunohistochemistry with stereological analysis showed that numbers of ERalpha immunoreactive cell nuclei per mm(3) of tissue in the caudal NTS were significantly greater in proestrus than in other groups of rats (P < 0.05). There were also differences among the groups in the extent of colocalisation of ERalpha in neurones immunoreactive for tyrosine hydroxylase and nitric oxide synthase. These results imply a complex pattern of region-specific oestrogen signalling in the NTS and suggest that ERalpha expression in this important autonomic nucleus may be related to circulating oestrogen levels. This may have consequences for the regulation of autonomic tone and baroreflex sensitivity when oestrogen levels decline, for example following menopause.

[Identification and expression of six drought responsive transcripts through differential display in desi cottion (Gossypium aroreum)]

There is not enough information available on drought-modulated gene(s) in Gossypium arboreum, which can be a valuable gene pool for improving modern cotton cultivars. In the present work differential display reverse transcriptase PCR (DDRT) was used to compare overall differences in gene expression between water stressed and control plants. By screening 93 primer-pair combinations DDRT technique resulted in up-regulation of 30 cDNA transcripts. Through reamplification and quality control assay 10 cDNA transcripts appeared false positive. The remaining 20-cDNA transcripts were extracted from the gel, reamplified, cloned and sequenced. Homology search revealed that 6 transcripts showed significant homology with known genes. Real-time RT-PCR showed that among 6 transcripts 5 showed significant over expression in water stressed leaves as compared to control. This is an important finding since there are only few reports of universal stress protein and transposable elements are available in plants but none in cotton under drought condition.

Effect of a common X-linked angiotensin II type 2-receptor gene polymorphism (-1332 G/A) on the occurrence of premature myocardial infarction and stenotic atherosclerosis requiring revascularization

OBJECTIVES

To assess the association of the angiotensin II type 2 (AT2) receptor (-1332 G/A) gene polymorphism with premature coronary artery disease (CAD) and investigate for a further role in both myocardial infarction and predominantly stenotic atherosclerosis requiring revascularisation.

METHODS AND RESULTS

We investigated 885 families, which consisted of at least one sibling affected with premature CAD and at least one unaffected sibling. Genotyping of subjects was performed using a restriction enzyme digestion of an initial 310 bp PCR fragment that included the AT2 (-1332 G/A) locus. The mean age of the 1143 individuals affected by premature CAD at the time of event was 50.6+/-9.1 years. The genetic data were analyzed for these families using the X-linked sibling transmission disequilibrium test (XS-TDT). We observed significant evidence for an association for the AT2 (-1332 G) locus and premature CAD (p-exact value=0.028). This was driven by a highly significant result in men (p-exact value=0.005). We performed further analyses to investigate for an association with myocardial infarction (Group 1) and stenotic atherosclerosis that was of sufficient severity as to require revascularization (Group 2). We found an increase in the frequency of the G/GG genotype in both Groups 1 and 2, being most marked in Group 2 (XS-TDT, p-exact value=0.0134); logistic regression (p=0.033, OR 1.38; 95% CI of 1.212-1.507).

CONCLUSION

We have observed evidence of association between the X-linked AT2 (-1332 G/A) polymorphism and premature CAD with further evidence of a statistically significant association with stenotic atherosclerosis requiring revascularization.

An evaluation of the beta-1 adrenergic receptor Arg389Gly polymorphism in individuals at risk of coronary events. A WOSCOPS substudy

AIMS

The Glycine389 variant of the beta-1 adrenergic receptor generates markedly less cAMP when stimulated in vitro than the more prevalent Arginine389 variant and may confer protection against coronary events similar to that observed with beta-blockers. The aim of this study was to ascertain whether this Glycine389 variant protects against coronary events.

METHODS AND RESULTS

We identified the genotype at position 389 of the beta1AR in 1554 individuals taken from men enrolled in the West of Scotland Coronary Prevention Study. Men with a coronary event (event group) were each matched for age and smoking status with two control subjects from the same cohort who had not had a coronary event (control group). We compared the distribution of genotypes in the event and control groups. Conditional logistic regression was used to calculate odds ratios for each of the genotypes. The prevalence of the three genotypes in the entire cohort was ArgArg 53.5%, ArgGly 39.6%, GlyGly 6.9%. The Arg389Gly beta-1 adrenergic receptor polymorphism was not associated with coronary events. Using the ArgArg genotype as the reference, the odds ratio for the ArgGly genotype was 1.1 (95% CI, 0.88-1.38) and for the GlyGly genotype it was 1.05 (95% CI, 0.68-1.62).

CONCLUSION

Our longitudinal case-control study demonstrates that the Glycine389 variant of the beta-1 adrenergic receptor does not protect against coronary events.

Protection of bronchoalveolar macrophages by granulocyte-macrophage colony-stimulating factor against dexamethasone suppression of fungicidal activity for Aspergillus fumigatus conidia

The objectives of this study were to: (i) see if granulocyte macrophage colony-stimulating factor (GM-CSF) could protect bronchoalveolar macrophages (BAM) against suppression by dexamethasone (DEX) and (ii) test the combined effect of GM-CSF and DEX on lymphocyte responses. Murine BAM killed Aspergillus fumigatus conidia by 33 +/- 4% (mean +/- SD) in a 2.5-h assay, unaffected by GM-CSF treatment. Killing by BAM treated with DEX (10(-7) M) for 48 h in vitro was reduced to 13 +/- 6%; however, if GM-CSF (500 U ml(-1)) was present during DEX treatment of BAM, killing of conidia (33 +/- 2%) by BAM was preserved. By contrast, DEX suppression of lymphocyte responses to concanavalin A was maintained during co-culture with GM-CSF. In sequence treatment experiments, initial treatment of BAM with GM-CSF protected against subsequent treatment with DEX. When macrophages were pretreated with DEX, GM-CSF could reverse suppression even when added subsequently, provided DEX treatment was discontinued. These data suggest that it may be possible to suppress lymphocyte responses with DEX, yet at the same time maintain BAM defenses with GM-CSF against pulmonary infections by conidia of A. fumigatus.

In vivo GM-CSF prevents dexamethasone suppression of killing of Aspergillus fumigatus conidia by bronchoalveolar macrophages

Dexamethasone (DEX) is a potent immunosuppressive agent used in the treatment of several disorders. However, despite its beneficial effects, DEX puts patients at risk for opportunistic infections, especially pulmonary aspergillosis. Previously we reported that in vitro granulocyte-macrophage colony-stimulating factor (GM-CSF) blocks the immunosuppressive action of DEX on bronchoalveolar macrophages (BAMs). Here we report that BAMs freshly isolated from mice treated intraperitoneally with DEX for 24 h had significantly (P<0.01) reduced killing of conidia, i.e., 15 +/- 5% conidia killed by BAMs from DEX-treated mice versus 35 +/- 3% by BAMs from mice given saline, 38 +/- 5% by BAMs from mice given GM-CSF, and 39 +/- 1% by BAMs from mice given both DEX and GM-CSF. On the other hand, in another compartment GM-CSF could not block the DEX reduction of spleen weight and spleen cellularity. Unlike GM-CSF, granulocyte colony-stimulating factor did not block DEX suppression of BAMs. GM-CSF given 24 h before DEX resulted in blocking of DEX suppression of BAM conidiacidal activity. However, when DEX was given 24 h before GM-CSF, DEX suppression of BAM was not reversed. These data show that GM-CSF in vivo blocks the in vivo immunosuppressive effects of DEX on BAM killing of conidia and suggest a potential use of GM-CSF in patients at risk for aspergillosis due to immunosuppressive DEX treatment.

Co-localization of c-Fos and neurotransmitter immunoreactivities in the cat brain stem after carotid sinus nerve stimulation

To reveal neurones in the cat medulla oblongata involved in carotid baroreceptor/chemoreceptor reflexes, the distribution of c-Fos oncoprotein immunoreactivity was studied following electrical stimulation of the right carotid sinus nerve. The neurochemistry of the activated neurones was investigated using antisera to tyrosine hydroxylase, neuropeptide Y, somatostatin, and glutamate. Nitric oxide containing neurones were identified using antiserum to nitric oxide synthase (NOS) and by the histochemical localization of nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase. Following sinus nerve stimulation numerous c-Fos-IR cells were detected both ipsilaterally and contralaterally in the nucleus tractus solitarii, the area postrema and throughout the ventrolateral medulla. Dual labelling studies revealed that 3.3% of c-Fos-immunoreactive cells in the nucleus tractus solitarii were also immunoreactive for tyrosine hydroxylase. The double labelled cells were scattered within the medial and ventrolateral subnuclei, predominantly rostral to obex. A higher proportion (10.3%) of c-Fos-IR cells in the ventrolateral medulla also showed tyrosine hydroxylase immunoreactivity. Caudal to obex, these were scattered in the reticular formation between the spinal trigeminal nucleus and the lateral reticular nucleus, while more rostrally they were found within the lateral reticular nucleus, the nucleus ambiguus and the lateral tegmental field. Cells expressing c-fos and reactive for glutamate, neuropeptide Y or NADPH-diaphorase (or NOS) were only rarely seen, and co-localization of c-Fos and somatostatin immunoreactivities was not seen. These results suggest that of the neurones forming pathways within the medulla activated on carotid sinus nerve stimulation, presumably mediating baro- and chemoreceptor reflexes, relatively few utilize catecholamines, glutamate, neuropeptide Y or nitric oxide as their transmitter substance.

Influence of peripheral targets on the expression of calcitonin gene-related peptide immunoreactivity in rat cranial motoneurones

Calcitonin gene-related peptide-like immunoreactivity (CGRP-ir) is displayed by motoneurons that innervate striated muscle but is absent from preganglionic parasympathetic motoneurons. One hypothesis to explain this is that CGRP gene expression in motoneurons is, in part, dependent on influences from the innervated organ. To test this hypothesis, we cross-anastomosed the right hypoglossal and cervical vagal nerves of rats so that the vagal motoneurons grew to innervate the musculature of the tongue. Following a recovery period of 17 to 52 weeks, the distribution of CGRP-ir in the dorsal motor vagal nucleus was determined in both cross-anastomosed animals and self-anastomosed control animals. Successful reinnervation of the tongue musculature by vagal motoneurons was demonstrated by showing that electrical stimulation of the central vagus/peripheral hypoglossal nerve produced a twitch of the tongue muscles. Motoneurones of the dorsal motor vagal nucleus, which now innervated the tongue were found to express CGRP-ir, which was evident from the double labeling of neurons with both horseradish peroxidase and CGRP-ir. Motoneurones of the dorsal motor vagal nucleus contralateral to the cross-anastomosis remained CGRP negative. Similarly, motoneurons of the dorsal motor vagal nucleus in control animals where the vagus nerve was self-anastomosed remained CGRP negative, showing that an induction of CGRP expression is not a result of nerve section itself. We suggest that a signal from the striated muscle transported retrogradely via the motor axon regulates expression of CGRP-ir in motoneurons.

Co-localization of neurotransmitter immunoreactivities in putative nitric oxide synthesizing neurones of the cat brain stem

The distribution of nitric oxide producing neurones in the medulla oblongata of the cat was investigated using nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase histochemistry, and nitric oxide synthase (NOS) immunohistochemistry. The pattern of staining obtained with both methods was found to be similar. Strongly diaphorase and NOS reactive neurones were present in the paramedian and lateral tegmental fields, including the regions occupied by the A1/C1 catecholamine cell groups, the nucleus ambiguus and lateral reticular nucleus, and in a number of sensory nuclei including the nucleus of the tractus solitarius and the dorsal column nuclei. The extent of co-localization of NADPH-diaphorase with a number of neuropeptides and neurotransmitters was investigated by combining NADPH-diaphorase histochemistry with immunocytochemistry for neuropeptide Y, somatostatin, glutamate, cholecystokinin and tyrosine hydroxylase. NADPH-diaphorase reaction product was observed in neurones immunoreactive for glutamate and somatostatin. These double-labelled cells were found in the paramedian region, lateral reticular field, the nucleus prepositus hypoglossi and in the rostral nucleus of the tractus solitarius. In the rostral ventrolateral medulla NADPH-diaphorase/somatostatin immunoreactive cells were found in the paragigantocellular nucleus. NADPH-diaphorase/glutamate immunoreactive cells overlapped the nucleus ambiguus, the lateral reticular nucleus and the A1/C1 catecholaminergic cell groups. In addition, a few NADPH-diaphorase/glutamate immunoreactive cells were found in the paraolivary area and gigantocellular tegmental field, in the external cuneate and infratrigeminal nuclei. The functional implications of the co-localization of nitric oxide with these neurotransmitters in areas of the medulla concerned with cardiovascular regulation is discussed.

Distribution of dopamine-containing neurons and fibres in the feline medulla oblongata: a comparative study using catecholamine-synthesizing enzyme and dopamine immunohistochemistry

The distribution of dopamine-immunoreactive neurons and fibres in the feline medulla oblongata was examined by immunocytochemistry with antisera to the catecholamine-synthesizing enzymes tyrosine hydroxylase, dopamine-beta-hydroxylase and phenylethanolamine-N-methyltransferase, and with antisera to the catecholamines dopamine and L-dihydroxyphenylalanine. Neurons immunoreactive for the catecholamine-synthesizing enzymes were found in two regions of the medulla, the ventrolateral A1 region and the dorsomedial A2 region. Double-staining studies with antisera to the enzymes indicated that a population of neurons within both regions were immunoreactive for tyrosine hydroxylase but not dopamine-beta-hydroxylase or phenylethanolamine-N-methyltransferase, implying that they synthesize dopamine. Studies using the dopamine antisera demonstrated the presence of dopamine-immunoreactive neurons in both the ventrolateral and dorsomedial regions of the medulla; in the dorsomedial region, they were found in the area postrema, nucleus tractus solitarius and dorsal motor vagal nucleus, mainly at levels caudal to the obex. Dopamine-immunoreactive fibres were found in several areas of the medulla including the nucleus tractus solitarius, inferior olive, dorsal motor vagal, spinal trigeminal, hypoglossal, cuneate, gracile, and raphe nuclei. Double-staining studies with antisera to dopamine and dopamine-beta-hydroxylase revealed a population of cells immunoreactive for dopamine alone. The presence of some double-stained neurons, however, implies some cross-reactivity of the dopamine antiserum with noradrenaline or adrenaline and/or recognition of dopamine present as a metabolic intermediary in some noradrenergic neurons. No L-dihydroxyphenylalanine-immunoreactive neurons were found in the medulla, although fibres were seen. These data provide evidence for the existence of catecholamine neurons which utilize dopamine as a final synthetic product within the medulla oblongata.

Immunolocalization of catecholamine enzymes, serotonin, dopamine and L-dopa in the brain of Dicentrarchus labrax (Teleostei)

Antisera to serotonin (5-HT), dopamine, and L-dopa, and to the catecholamine synthesizing enzymes, tyrosine hydroxylase (TH), dopamine beta-hydroxylase (DBH), and phenylethanolamine N-methyl transferase (PNMT), were used to localize monoamine containing neurones in the brain of Dicentrarchus labrax (sea bass). In the brain stem, 5-HT-immunoreactive (ir) neurones were recognized in the ventrolateral medulla, vagal motor area, medullary, and mesencephalic raphe nuclei and in the dorsolateral isthmal tegmentum. In the hypothalamus, liquor-contacting 5-HT neurones were seen in various regions of the paraventricular organ. Virtually all regions of the brain contained a dense innervation by 5-HT fibres and terminals. DBH-ir neurones were restricted to three brain stem areas: the locus coeruleus, the area postrema, and the reticular formation of the lower medulla. Neurones in these three groups also displayed TH-ir, and in the latter area, PNMT-ir in addition. In the locus coeruleus and area postrema, TH-ir neurones outnumbered DBH-ir neurones, an observation substantiated by the presence of dopamine-ir neurones. In the forebrain, dopamine- and TH-ir neurones were found in the olfactory bulb, ventral/central telencephalon, periventricular preoptic, and suprachiasmatic areas, dorsolateral and ventromedial thalamus, and posterior tuberal nucleus. In the paraventricular organ, the distribution and morphology of dopamine-ir neurones was similar to that observed with anti-5-HT, but the vast majority of cells were not TH-ir, suggesting accumulation of dopamine by uptake from the ventricle, rather than by synthesis. L-dopa-ir neurones were found only in the central telencephalon, preoptic recess, and dorsolateral thalamus. Fibres and terminals immunoreactive for dopamine, TH, and DBH showed a broadly similar distribution. The results are discussed in relation to the monoaminergic systems previously reported in other teleostean species and the mammalian brain.