β-Endorphin like immunoreactivity of brain,pituitary gland and plasma of rats submitted to postnatal protein malnutrition: Effect of behavioral training

Wistar-derived rats were raised and maintained either on a normal- (25% casein) or on a low-protein (8% casein) diet until the age of 100 to 114 days. Both diets were isocaloric and contained an adequate supply of salts and vitamins. There were gross differences in body, brain and pituitary weight between the two groups. In addition, the brain and pituitary content of β-endorphin like immunoreactivity was lower in the protein malnourished rats, and three different forms of training (50 tone-footshock shuttle avoidance trials; 50 tones alone (habituation); 50 footshocks alone) caused a depletion of brain β-endorphin like immunoreactivity in the normal, but not in the malnourished rats. Footshock stimulation caused, in addition, a pituitary decrease and a plasma increase of β-endorphin like immunoreactivity, also restricted to the normal diet group. Performance in the habituation and in the shuttle avoidance tasks was similar in the two groups, despite the different responsiveness of their brain and pituitary β-endorphin systems to training and/or stimulation. In view of the possible involvement of these systems in learning suggested by these and by previous data, it seems likely that the neurohumoral regulation of habituation and avoidance learning may be different in rats submitted to protein malnutrition when compared to controls.     

Extracellular Ca2+ and the effect of antidiuretic hormone on the water permeability of the toad urinary bladder: An example of flow-induced alteration of flow

Summary The extracellular Ca²⁺ requirement for antidiuretic hormone (ADH) stimulation of water permeability in the toad urinary bladder has been critically examined. The polarity of the tissue was maintained with 1mm Ca²⁺ in the mucosal bathing medium and a serosal bath nominally free of Ca²⁺. Under these condition, ADH-induced osmotic water flow was inhibited by more than 60% while enhancement of the diffusional permeability to water was unaffected. Structural studies revealed that low serosal Ca²⁺ led to parallel alterations in epithelial architecture that amounted to a significant distorition of the osmotic water pathway. Prevention of these alterations, or restoration of normal cell-cell contact showed that the reduction of serosal Ca²⁺ did not restrict hormonal action,per se, but that it resulted in a weakening of cell-cell junctions such that intercellular space distension during water flow occurred to a point where the geometric conditions for maintenance of osmotic flow were compromised. We conclude that extracellular Ca²⁺ is not a requirement for the molecular aspects of ADH action but that, in its absence, a direct measurement of ADH-induced osmotic flow proves to be an inaccurate index of the hormone-generated changes in epithelial transport characteristics. Under certain conditions the ADH-effect on the tissue's hydraulic permeability is probably best assessed by measurement of the diffusional permability to water; although accuracy in this determination is difficult, it is not as strongly dependent on tissue geometry.     

Water utilization of tropical hardwood hammocks of the Lower Florida Keys

Summary Predawn water potential of representative plant species, together with stable isotope composition of stem water and potential water sources were investigated in four low-elevation tropical hardwood hammocks in the Lower Florida Keys, during a one year period. Hammock species had the lowest water potentials when soil water content was low and/or soil salinity was high, but differences in groundwater salinity had no effect on the water potential. Comparison of D/H ratio of plant stem water with soil and ground water corroborates the conclusion that they are primarily utilizing soil water and not groundwater. Thus, tropical hardwood hammocks are buffered from saline groundwater, and are able to thrive in areas where groundwater salinity is as high as 25. The effect of sea level rise on these forests may depend more on changes in the frequency of tidal inundation of the soil surface than on changes in groundwater salinity.     

Trypanosoma cruzi: cloning and expression of an antigen recognized by acute and chronic human chagasic sera.

Here we describe the characterization of a Trypanosoma cruzi DNA sequence (clone A13) that codes for a polypeptide recognized by IgM and IgG antibodies from sera of acute and congenital chagasic patients. Antibodies to A13 antigen are also detected in the sera of chronic patients with different clinical forms of Chagas' disease, but not in sera of patients with leishmaniasis or other parasitic diseases. The antigenic determinants encoded by clone A13 are found in amastigotes and trypomastigotes of several T. cruzi strains, but not in the noninfective epimastigotes. The DNA sequence of the recombinant clone reveals one open reading frame encoding 251 amino acids without tandemly repeated sequences. Our data suggest that the A13 antigen may be useful for the development of serodiagnostic procedures.     

Comparison of the folding of 2-Keto-3-deoxy-6-phosphogluconate aldolase,triosephosphate isomerase and pyruvate kinase: Implications in molecular evolution

The 8-fold α/β barrel conformation of 2-keto-3-deoxy-6-phosphogluconate aldolase has been compared to that of triosephosphate isomerase and the A-domain of pyruvate kinase. There are eight supersecondary structure units (α/β) in each of these proteins, and the comparisons were carried out in orientations corresponding to each of the possible congruences, i.e. first to first, first to second,… of the supersecondary structure units. The comparison of the C_α structure of the main chain folding of the three enzymes indicated about 150 equivalences with rootmean-square differences of about 3.1 Å, with no orientational preference, including the aldolase with itself. In addition, there is no sequence homology between the aldolase and the isomerase, and no indication of gene duplication in the former. The lack of orientational preference among the three enzymes suggests convergence to a fold of exceptional stability. However, all three enzymes activate a CH bond adjacent to a carbonyl, and their active sites correspond to the f strand, F helix region of the α/β barrel, thus contradicting the foregoing and suggesting divergent evolution from a common precursor. Other and similar arguments are also presented for and against convergent evolution of these three strikingly similar enzymes.     

Chemical composition of the plasma membrane from epimastigote forms of Trypanosoma cruzi

The chemical composition of two plasma membrane fractions from epimastigote forms of Trypanosoma cruzi is reported. Fraction M, a preparation obtained by conventional methods of cell fractionation is composed of 31% proteins, 34% lipids, 16% carbohydrates and 3% of the lipopeptidophosphoglycan. Phospholipids and sterols account for 7.5 and 9%, respectively, of the total mass. Phosphatidylethanolamine is the major phospholipid in fraction M, representing 45% of the total membrane phospholipids. The other fraction, fraction V (vesicles), was obtained by treatment of the cell with a vesiculating agent. This fraction contains 42% lipids, 20% carbohydrates, 13% proteins and 21% of the lipopeptidophosphoglycan. Phospholipids and sterols make up 17 and 8%, respectively, of the total mass of this fraction. Phosphatidylcholine and phosphatidylethanolamine are the main phospholipids found in fraction V. Phosphonolipids and sialic acid have not been detected in either membrane fraction. Sodium dodecyl sulphate polyacrylamide gel electrophoretic analysis show that the glycoproteins ABC and the lipopeptidophosphoglycan are 50- and 10-times more concentrated, respectively, in fractions V and M than in the whole cell homogenate. The high molar sterol/phospholipid ratio found in fraction M suggests that this fraction is less fluid than fraction V, perhaps reflecting a migration of certain membrane components in the presence of the vesiculating agent. Hence, fraction M is, probably, more representative of the epimastigote plasma membrane as a whole than fraction V.     

PERFUSION FOR MYOCARDIAL REVASCULARIZATION WITHOUT AN ARTIFICIAL OXYGENATOR (New Method to Reduce Surgical Morbidity)

Thirteen patients were submitted to direct myocardial revascularization (saphenous vein graft) without the use of an artificial oxygenator. The perfusion was done by a left ventricle-to-aorta bypass and autogenous oxygenation. Most patients had three grafts implanted plus endarterectomy of the distal right coronary artery. There was one hospital death that was apparently not related to the method used. Perfusion time ranged from 45 minutes to 4 hours. Body temperature during perfusion was kept between 25 and 30 degrees C. Perfusion flow was maintained between 25 to 50 ml per kg of body weight per minute. Ischemic, hypothermic cardiac arrest was employed. We demonstrated for the first time that perfusion for this kind of heart surgery could be done with no artificial oxygenators and, apparently, is safer for the patients. There were no bleeding problems even in perfusions as long as 4 hours. There was no respiratory dysfunction, and artificial respiration was used for only 6 to 12 hours. The patients awoke at the end of surgery with no signs or symptoms of central nervous system damage, and vasopressor drugs were rarely used after surgery. Although the experience is very small, it suggests that many postoperative problems, especially those related to bleeding and respiratory dysfunction may be reduced or eliminated by this new method.     

Synchronous growth of a freshwater diatom Melosira italica under natural environment

Summary A filamentous diatom Melosira italica was collected at the beginning of rainy season from a shallow lake in the tropical savanna region in Brazil. Even the sample taken from surface water contained empty cells in high percentages. The number of cells per filament of M. italica showed a peculiar pulse-like frequency distribution with peak values at 4, 8, 12 and 16. Evidences of the synchronous cell division in this planktonic diatom under natural environment are discussed.     

Dynamics of Salmonella enterica and antimicrobial resistance in the Brazilian poultry industry and global impacts on public health

Non-typhoidal Salmonella enterica is a common cause of diarrhoeal disease; in humans, consumption of contaminated poultry meat is believed to be a major source. Brazil is the world’s largest exporter of chicken meat globally, and previous studies have indicated the introduction of Salmonella serovars through imported food products from Brazil. Here we provide an in-depth genomic characterisation and evolutionary analysis to investigate the most prevalent serovars and antimicrobial resistance (AMR) in Brazilian chickens and assess the impact to public health of products contaminated with S. enterica imported into the United Kingdom from Brazil. To do so, we examine 183 Salmonella genomes from chickens in Brazil and 357 genomes from humans, domestic poultry and imported Brazilian poultry products isolated in the United Kingdom. S. enterica serovars Heidelberg and Minnesota were the most prevalent serovars in Brazil and in meat products imported from Brazil into the UK. We extended our analysis to include 1,259 publicly available Salmonella Heidelberg and Salmonella Minnesota genomes for context. The Brazil genomes form clades distinct from global isolates, with temporal analysis suggesting emergence of these Salmonella Heidelberg and Salmonella Minnesota clades in the early 2000s, around the time of the 2003 introduction of the Enteritidis vaccine in Brazilian poultry. Analysis showed genomes within the Salmonella Heidelberg and Salmonella Minnesota clades shared resistance to sulphonamides, tetracyclines and beta-lactams conferred by sul2, tetA and bla_CMY-2 genes, not widely observed in other co-circulating serovars despite similar selection pressures. The sul2 and tetA genes were concomitantly carried on IncC plasmids, whereas bla_CMY-2 was either co-located with the sul2 and tetA genes on IncC plasmids or independently on IncI1 plasmids. Long-term surveillance data collected in the UK showed no increase in the incidence of Salmonella Heidelberg or Salmonella Minnesota in human cases of clinical disease in the UK following the increase of these two serovars in Brazilian poultry. In addition, almost all of the small number of UK-derived genomes which cluster with the Brazilian poultry-derived sequences could either be attributed to human cases with a recent history of foreign travel or were from imported Brazilian food products. These findings indicate that even should Salmonella from imported Brazilian poultry products reach UK consumers, they are very unlikely to be causing disease. No evidence of the Brazilian strains of Salmonella Heidelberg or Salmonella Minnesota were observed in UK domestic chickens. These findings suggest that introduction of the Salmonella Enteritidis vaccine, in addition to increasing antimicrobial use, could have resulted in replacement of salmonellae in Brazilian poultry flocks with serovars that are more drug resistant, but less associated with disease in humans in the UK. The plasmids conferring resistance to beta-lactams, sulphonamides and tetracyclines likely conferred a competitive advantage to the Salmonella Minnesota and Salmonella Heidelberg serovars in this setting of high antimicrobial use, but the apparent lack of transfer to other serovars present in the same setting suggests barriers to horizontal gene transfer that could be exploited in intervention strategies to reduce AMR. The insights obtained reinforce the importance of One Health genomic surveillance.     

Cryptogenic hepatitis patients have a higher Bartonella sp.-DNA detection in blood and skin samples than patients with non-viral hepatitis of known cause

BackgroundThis study aimed to assess the prevalence of Bartonella sp.-DNA detection in blood and skin samples from patients with non-viral end-stage liver disease awaiting liver transplantation.Methodology/Principal findingsBlood samples and healthy skin fragments from 50 patients were tested using microbiological and molecular methods. Fifteen patients had cryptogenic hepatitis (CH) and 35 had alcoholic, drug-induced or autoimmune liver disease. DNA was extracted from whole blood and liquid culture samples, isolates, and skin fragments. Thirteen of the 50 patients (26%) had Bartonella henselae DNA detection in their blood (9/50) and/or skin (5/50) samples. Colonies were isolated in 3/50 (6%) and infection was detected in 7/50 (14%) of the 50 patients. B. henselae-DNA detection was more prevalent in patients with CH than in other patients (p = 0.040). Of 39 patients followed-up for at least two years, a higher mortality rate was observed among patients with CH infected with B. henselae (p = 0.039).Conclusions/SignificanceFurther studies assessing the role of B. henselae infection in the pathogenesis of hepatitis patients must be urgently conducted.