Left ventricular response to sublingual administration of nitroglycerin

The aim of this study was to investigate whether the rapid improvement of the clinical condition of patients after administration of nitroglycerin can be documented objectively using the apexcardiogram. The study was performed on 28 male patients with coronary heart disease whose clinical condition allowed us to perform the initial polygraphic examination during an attack of angina pectoris. The heart rate and three apexcardiographic indexes were determined from non-invasive polygraphic tracings. The first index was the a/H (ratio: amplitude of apexcardiographic "a" wave to total amplitude of apexcardiogram). The second and third were the velocity of the anterior left ventricular wall motion during both isovolumic contraction (VwmC) and isovolumic relaxation (VwmR) of the left ventricle. The mean differences from initial values were calculated after 2, 4, 6 and 10 min following administration of nitroglycerin. Significant changes already occurred during the second minute after administration of nitroglycerin. All parameters remained significantly changed up to the 10th minute after this treatment. According to our results, the cardiovascular response to sublingual administration of nitroglycerin can be objectively evaluated by apexcardiography.     

Presence of polioviruses and other enteral viruses in sewage: a survey in the Czech Socialistic Republic 1969-1976

Monitoring polioviruses in sewage is a permanent task within the poliomyelitis vaccination control programme in Czechoslovakia. The results of sewage examination in certain localities of the CSR in the years 1969 to 1976 are reported. During the study years, nearly 3600 samples of sewage were examined. The yield was about 9 percent of samples positive for polioviruses and 22 per cent of samples positive for other viruses. The virus positivity rate was roughly the same in samples from municipal sewers and samples from children's facilities. The majority of polioviruses were detected within 3 to 4 months after mass vaccination campaigns, which in Czechoslovakia are carried out in spring. In some years types 2 and 3 polioviruses tended to occur in later months after vaccination as well. Antigenic characterization of the polioviruses isolated in Prague showed that polioviruses possessing an rct+ marker and antigenically related but not identical with the original vaccine strains were sometimes present late during the intervals between vaccination campaigns. It may be assumed that vaccine strains which have been in circulation for sufficiently long time are subject to a gradual change or that vaccine-like strains have been imported.     

Anti-inflammatory effect of l-cysteine (a semi-essential amino acid) on 5-FU-induced oral mucositis in hamsters

Oral mucositis is an inflammation of the oral mucosa mainly resulting from the cytotoxic effect of 5-fluorouracil (5-FU). The literature shows anti-inflammatory action of l-cysteine (l-cys) involving hydrogen sulfide (H₂S). In view of these properties, we investigate the effect of l-cys in oral mucositis induced by 5-FU in hamsters. The animals were divided into the following groups: saline 0.9%, mechanical trauma, 5-FU 60–40 mg/kg, l-cys 10/40 mg and NaHS 27 µg/kg. 5-FU was administered on days 1st to 2nd; 4th day excoriations were made on the mucosa; 5th–6th received l-cys and NaHS. For data analysis, histological analyses, mast cell count, inflammatory and antioxidants markers, and immunohistochemistry (cyclooxygenase-2(COX-2)/inducible nitric oxide synthase (iNOs)/H₂S) were performed. Results showed that l-cys decreased levels of inflammatory markers, mast cells, levels of COX-2, iNOS and increased levels of antioxidants markers and H₂S when compared to the group 5-FU (p < 0.005). It is suggested that l-cys increases the H₂S production with anti-inflammatory action in the 5-FU lesion.

     

Sequential pathological studies in Asian water buffaloes infected intratracheally with Absidia corymbifera

Zygomycosis was produced experimentally in Asian water buffalo calves (Bubalus bubalis) by intratracheal inoculation of sporangiospores of Absidia corymbifera. Infected animals exhibited dullness, depression, partial anorexia, initial pyrexia, mucopurulent nasal and ocular discharge and coughing during the first week. There was no mortality at any stage of the experiment, which continued for 30 days. The gross and microscopic lesions were restricted to the lungs and there was no dissemination of the fungus to other organs. Gross and microscopic changes in the lungs were observed up to the 20th day post-infection. Gross lesions consisted of pneumonic consolidation of the antero-ventral lobes of the lungs. Microscopic changes consisted of granulomatous reactions with well developed pulmonary granulomas. Distorted hyphae of A. corymbifera were demonstrated in tissue sections up to 15 days post inoculation. Re-isolation of the fungus was achieved consistently for up to 15 days. It is concluded that intratracheal inoculation of A. corymbifera in buffalo calves leads to significant pathological changes in the lungs, but the disease appears to be self limiting 20 days following inoculation.     

Precision of host sanctions in the fig tree–fig wasp mutualism: consequences for uncooperative symbionts

Host sanctions that reduce the relative fitness of uncooperative symbionts provide a mechanism that can limit cheating and thus stabilise mutualisms over evolutionary timescales. Sanctions have been demonstrated empirically in several mutualisms. However, if multiple individual symbionts interact with each host, the precision with which individual cheating symbionts are targeted by host sanctions is critical to their short‐ and long‐term effectiveness. No previous empirical study has directly addressed this issue. Here, we report the precision of host sanctions in the mutualism between fig trees and their pollinating wasps. Using field experiments and molecular parentage analyses, we show that sanctions in Ficus nymphaeifolia act at the level of entire figs (syconia), not at the level of the individual flowers within. Such fig‐level sanctions allow uncooperative wasps, which do not bring pollen, to avoid sanctions in figs to which other wasps bring pollen. We discuss the relevance of sanction precision to other mutualisms.     

The role of <Emphasis Type="Italic">Calamagrostis</Emphasis> communities in preventing soil acidification and base cation losses in a deforested mountain area affected by acid deposition

The effects of grass growth and N deposition on the leaching of nutrients from forest soil were studied in a lysimeter experiment performed in the Moravian-Silesian Beskydy Mts. (the Czech Republic). It was assumed that the grass sward formed on sites deforested due to forest decline would improve the soil environment. Lysimeters with growing acidophilous grasses (Calamagrostis arundinacea and C. villosa), common on clear-cut areas, and with unplanted bare forest soil were installed in the deforested area affected by air pollution. Wet bulk deposition of sulphur in SO₄^2– corresponded to 21.6–40.1 kg ha^–1 and nitrogen in NH₄⁺ and NO₃^– to 8.9–17.4 kg N ha^–1, with a rain water pH of 4.39–4.59 and conductivity of 18.6–36.4 S cm^–1 during the growing seasons 1997–1999. In addition, the lysimeters were treated with 50 kg N ha^–1 yr^–1 as ammonium nitrate during the 3 years of the experiment. Rapid growth of planted grasses resulted in a very fast formation of both above- and below-ground biomass and a large accumulation of nitrogen in the tissue of growing grasses. The greatest differences in N accumulation in aboveground biomass were observed at the end of the third growing season; in C. villosa and C. arundinacea, respectively, 2.66 and 3.44 g N m^–2 after addition of nitrogen and 1.34 and 2.39 g N m^–2 in control. Greater amounts of nitrogen were assessed in below-ground plant parts (9.93–12.97 g N m^–2 in C. villosa and 4.29–4.39 g N m^–2 in C. arundinacea). During the second and third year of experiment, the following effects were the most pronounced: the presence of growing grasses resulted in a decrease of both the acidity and conductivity of lysimetric water and in a lower amount of leached nitrogen, especially of nitrates. Leaching of base cations (Ca²⁺ and Mg²⁺) was two to three times lower than from bare soil without grasses. An excess of labile Al³⁺ was substantially eliminated in treatments with grasses. Enhanced N input increased significantly the acidity and losses of nutrients only in unplanted lysimeters. The leaching of N from treatments with grasses (3.9–5.6 kg N ha^–1) was 31–46% of the amount of N in wet deposition. However, the amount of leached N (4.2–6.0 kg N ha^–1) after N application was only 7.1–8.9% of total N input. After a short three year period, the features of soil with planted grasses indicated a slight improvement: higher pH values and Ca²⁺ and Mg²⁺ contents. The ability of these grass stands to reduce the excess nitrogen in soil is the principal mechanism modifying the negative impact on sites deforested by acid depositions. Thus it is suggested that grass sward formation partly eliminates negative processes associated with soil acidification and has a positive effect on the reduction of nutrient losses from the soil.     

Prevalence of aerobic and anaerobic uterine bacteria during peripartum period in normal and dystocia-affected buffaloes

Parturition complications predispose establishment of uterine infections, which in turn affect subsequent fertility. The aim of present study was to characterize and compare the type of bacterial flora prevalent within the uterine lumen of dystocia-affected buffaloes and compare them with the normally calving buffaloes. The study was conducted on 40 buffaloes; of which 10 calved normally (Group I) and 30 were treated for dystocia (Group II). Bacteriological examination was performed using uterine swabs, which were collected before delivery, immediately after delivery and day's 24-60 postpartum. A total of 30 uterine swabs from Group I and 79 swabs from Group II were collected, of which 19 (63.3%) and 71 (89.9%) yielded significant bacterial growth, respectively. A total of 205 isolates belonging to 10 different genera of bacteria were identified, 8 facultative anaerobes and 2 obligate anaerobes. In Group II, 91.6% of the bacteria positive swabs (n = 71) yielded mixed cultures, whereas the remainder being pure cultures. In contrast, 89.5% of the bacteria positive swabs of Group I (n = 19) yielded pure cultures. Mixed infections comprised mostly Arcanobacter (Actinomyces) pyogenes together with obligate anaerobes, Fusobacterium spp. and Bacteroides spp. In Group II, the frequency of incidental and coliform group bacteria was highest at the time of parturition, i.e., before and immediately after delivery, and decreased to nil during the 24-60-day postpartum period. However, in Group I, the incidental and coliform group of bacteria present at the time of parturition apparently persisted beyond the period when uterine involution is complete. The frequency of obligate anaerobes and A. pyogenes at the time of parturition was nil in the Group I while they predominated in dystocia-affected buffaloes (Group II). During the postpartum period of 24-60 days, the frequency of both obligate anaerobes and A. pyogenes increased significantly in Group II, whereas in Group I, only occasional isolates were obtained. To conclude, at the time of calving the prevalence of obligate anaerobes and A. pyogenes occurring in combination was highest in dystocia-affected buffaloes, and further increased in the postpartum period suggesting that these infections act synergistically.     

BR-bombesin: a novel bombesin-related peptide from the skin secretion of the Chaco tree frog (Boana raniceps) with physiological gastric effects

Amino Acids - Bombesin mediates several biological activities in the gastrointestinal (GI) tract and central nervous system in mammals, including smooth muscle contraction, secretion of GI hormones...     

Why mutualist partners vary in quality: mutation–selection balance and incentives to cheat in the fig tree–fig wasp mutualism

Mutualisms between species are ecologically ubiquitous but evolutionarily puzzling. Host discrimination mechanisms that reduce the fitness of uncooperative symbionts can stabilise mutualism against collapse, but also present a paradox – if discrimination is effective, why do uncooperative symbionts persist? Here, we test whether mutations or fitness benefits of cheating best explain the prevalence of uncooperative wasps in the fig tree–fig wasp mutualism. By combining theory with field‐collected data we demonstrate that the proportions of pollen‐free wasps of strongly discriminating hosts are reached with reasonable mutation rates. In contrast, in weakly discriminating hosts, the required mutation rates, assuming a single locus, are untenably high, but the required cheater advantages fall within expected ranges. We propose that when discrimination is weak, uncooperative symbionts proliferate until they reach the equilibrium proportion that balances costs and benefits of cheating. Our results suggest that mechanisms that resolve the paradox of uncooperative symbionts differ among host species.     

Qualitative and quantitative detection of aflatoxin B1 in poultry sera by enzyme-linked immunosorbent assay

An indirect competitive inhibition type enzyme-linked immunosorbent assay (ELISA) has been developed for the detection of aflatoxin B₁, in poultry sera. Preincubation of aflatoxin B₁, samples with the antibody prior to competition yielded better results in terms of higher sensitivity. After competition, amount of antibody bound to solid phase was measured by incubation with anti-rabbit immunoglobulins coupled with horse raddish peroxidase. Intensity of colour decreased as the amount of free aflatoxin B₁, increased. Final detection of aflatoxin B₁, was made by (i) visual comparison with standard aflatoxin B₁ using dot-ELISA (qualitative) and (ii) by plate-ELISA, where optical density was measured at 492 nm (quantitative). Plate-ELISA was more sensitive than dot-ELISA, with sensitivity limits being 100 fg and 1 pg per 10 μl, respectively. However, due to ease and speed of performance, dot-ELISA has greater potential as a test for the diagnosis of mycotoxicosis at the field level.