牵拉猫左心房所致的肾效应

本实验在50只麻醉猫中研究了牵拉左心房(LAS)对尿量(UV)、尿钠(U_(Na)V)和尿钾(U_KV)排出量的影响。在迷走神经完整的动物,LAS 导致 UV,U_(Na)V 和 U_KV(P<0.001)明显增加。切断迷走神经后 LAS 仍能使 UV,U_(Na)V 有所增加(p<0.01),但增加量明显低于迷走神经完整的动物(P<0.005)。在迷走神经完整的猫滴注肝素(10U/min/mg)后,LAS 也能引起 UV,U_(Na)V 和 U_KV 的增加,但增值明显低于没有滴注肝素的猫。在迷走神经切除后滴入肝素,则 LAS 的肾效应消失(p>0.05)。切断左侧肾神经后,LAS 引起神经完整肾尿量和尿钠排出显著增加(P<0.001)。而去神经肾对 LAS 的效应虽减弱,但其增值仍有显著性。两侧肾效应的差异,在统计学上是显著的(P<0.05)。上述结果说明,LAS 在麻醉猫中能引起尿量,尿钠和尿钾明显增加,这些效应是神经反射和体液机制共同作用的结果。     

Radioimmunoassay of met-enkephalin in microdissected areas of paraformaldehyde-fixed rat brain

We studied the effect of various sample preparation procedures on rat brain met-enkephalin content, measured by radioimmunoassay. Whole brain met-enkephalin content of rats killed by decapitation followed by immediate tissue freezing was similar to that of rats killed by microwave irradiation and to those of rats anesthetized with pentobarbital or halothane before killing, whether previously perfused with paraformaldehyde or not. In contrast, a decrease (up to 80%) in met-enkephalin concentrations was observed when brain samples were frozen and thawed to mimic the procedure utilized in the “punch” technique for analysis of discrete brain nuclei. This decrease was totally prevented by paraformaldehyde perfusion of the brain prior to sacrifice. Brain perfusion did not alter the amount of immunoassayable met-enkephalin extracted from tissue or its profile after Sephadex chromatography. Paraformaldehyde perfusion results in better morphological tissue preservation and facilitates the “punch” dissecting technique. Paraformaldehyde perfusion may be the procedure of choice for the measurement of neuropeptides in specific brain nuclei dissected by the “punch” technique.     

Quantitative in vitro autoradiographic characterization of [125I]angiotensin III binding sites in rat adrenal gland

A single class of high-affinity binding sites for [125I]angiotensin III and [125I]angiotensin II were found in rat adrenal medulla and zona glomerulosa by quantitative autoradiography. In the medulla, Kd were 1.46 and 1.16 nM, and Bmax 1700 and 1700 fmol/mg protein, for [125I]angiotensin II and [125I]angiotensin III, respectively. In the zona glomerulosa, Kd were 0.86 and 0.90 nM, and Bmax 790 and 560 fmol/mg protein, for [125I]angiotensin II and [125I]angiotensin III, respectively. Unlabeled angiotensin III and angiotensin II displaced [125I]angiotensin III with similar potency in both adrenal zona glomerulosa and medulla. Our findings suggest that angiotensin III and angiotensin II might share the same binding sites in adrenal gland and support the hypothesis of a role for angiotensin III in the adrenal medulla and zona glomerulosa.     

Water Relations and Cell Wall Elasticity Quantities in Phaseolus vulgaris Leaves

The investigations were designed to test osmotic adjustment,cell wall bulk elastic modulus and stomatal behaviour duringand after water stress and rewatering in the primary and firsttrifoliolate leaf of Phaseolus vulgaris. Leaf water relationsquantities fully recovered after rewatering within a few hours;diffusion resistance to vapour flow, however, required 6 h.Leaf growth recovery was considerably delayed. Osmotic adjustmentwas absent during water stress in both the primary and the firsttrifoliolate leaf. The bulk elastic modulus (_v), however, waslower for the primary leaf (higher elasticity) than for thetrifoliolate leaves. These two types of leaves differed in theirdrought resistance in that the primary leaf exhibited wiltingat the end of the stress period (7 d) while the trifoliolateleaf remained relatively turgid. The bulk elastic modulus ofthe cell wall changed almost proportionally with the turgorpressure (_p). The structure coefficient (), an indicator forthe intensity of change of the bulk elastic modulus with turgorwas higher for the primary than for the first trifoliolate leaf.The leaf diffusion resistance (r), below the turgor loss point,changed proportionally with the solute potential with very similarregression lines for the relation of (r) versus RWC ¹. The datasuggest that greater drought resistance of the first trifoliolateleaf is related to a decreased bulk elastic modulus, but notto osmotic adjustment nor to differences in stomatal resistanceduring water stress. Key words: Phaseolus vulguris, Water stress, Recovery, Cell wall elasticity     

Combined effect of synthetic enterocin CRL35 with cell wall,membrane‐acting antibiotics and muranolytic enzymes against Listeria cells

Aims: To evaluate the inhibition effectiveness of enterocin CRL35 in combination with cell wall, membrane‐acting antibiotics and muranolytic enzymes against the foodborne pathogen Listeria. Methods and Results: Synthetic enterocin CRL35 alone and in combination with monensin, bacitracin, gramicidin, mutanolysin and lysozyme were used in this study. Minimal inhibitory concentration (MIC) and fractional inhibitory concentration (FIC) index assays were performed using Listeria innocua 7 and Listeria monocytogenes FBUNT as sensitive strains. Antibiotics showed positive interactions with the bacteriocin in both strains tested. On the other hand, when mutanolysin and enterocin CRL35 were added to resting cells in a buffer system, the lytic effect of mutanolysin was enhanced. However, the addition of mutanolysin showed no effect on the growth of L. innocua 7 cells in a culture medium. Moreover, mutanolysin allowed the overgrowth of L. innocua 7 cells to an OD similar to control cells in the presence of inhibitory concentration of enterocin CRL35. In contrast, the combination of lysozyme and enterocin CRL35 resulted in a 50% inhibition of the L. innocua 7 growth. Conclusions: Based on our results, we conclude that the combination of synthetic enterocin CRL35 with some antibiotics is effective against L. innocua 7 and L. monocytogenes FBUNT cells, and more importantly the amount of these agents to be used was considerably reduced. The effectiveness of the combination of synthetic enterocin CRL35 with muramidases seems to depend on complex environments, and more detailed studies need to be performed to elucidate this issue. Significance and Impact of the Study: Enterocin CRL35 represents a promising agent that not only can ensure the quality and safety of food but it can also be combined with several antimicrobial agents important in the medical field.     

New differences between the Wistar rat and Octodon degus, a putative laboratory animal resistant to morphine

1. The effects of CNS depressants (methadone and alcohol) and natural neurotransmitters (NA and ACh) are studied in O. degus. 2. O. degus shows resistance to methadone in the formalin algesiometric test and EEG. 3. Ethanol elimination profile suggest the presence of an atypical alcohol dehydrogenase in O. degus 4. O. degus is extremely resistant to the pressor effects of noradrenaline 5. the isolated atrium of this rodent is 40 times more sensitive to the negative chronotropic effect of methadone, than the rat atrium. 6. These effects could be explained in terms of an important catecholamine and endorphin co-secretion from adrenal glands in O. degus.     

Evolution of the brain and sensory organs in Sphenisciformes: new data from the stem penguin Paraptenodytes antarcticus

Penguins have undergone dramatic changes associated with the evolution of underwater flight and subsequent loss of aerial flight, which are manifest and well documented in the musculoskeletal system and integument. Significant modification of neurosensory systems and endocranial spaces may also be expected along this locomotor transition. However, no investigations of the brain and sensory organs of extinct stem lineage Sphenisciformes have been carried out, and few data exist even for extant species of Spheniscidae. In order to explore neuroanatomical evolution in penguins, we generated virtual endocasts for the early Miocene stem penguin Paraptenodytes antarcticus, three extant penguin species (Pygoscelis antarctica, Aptenodytes patagonicus, Spheniscus magellanicus), and two outgroup species (the common loon Gavia immer and the Laysan albatross Phoebastria immutabilis). These endocasts yield new anatomical data and phylogenetically informative characters from the brain, carotid arteries, pneumatic recesses, and semicircular canal system. Despite having undergone over 60 million years of evolution since the loss of flight, penguins retain many attributes traditionally linked to flight. Features associated with visual acuity and proprioception, such as the sagittal eminence and flocculus, show a similar degree of development to those of volant birds in the three extant penguins and Paraptenodytes antarcticus. These features, although clearly not flight‐related in penguins, are consistent with the neurological demands associated with rapid manoeuvring in complex aquatic environments. Semicircular canal orientation in penguins is similar to volant birds. Interestingly, canal radius is grossly enlarged in the fossil taxon Pa. antarcticus compared to living penguins and outgroups. In contrast to all other living birds, the contralateral anterior tympanic recesses of extant penguins do not communicate. An interaural pathway connecting these recesses is retained in Pa. antarcticus, suggesting that stem penguins may still have employed this connection, potentially to enhance directional localization of sound. Paedomorphosis, already identified as a potential factor in crown clade penguin skeletal morphology, may also be implicated in the failure of an interaural pathway to form during ontogeny in extant penguins. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 166 , 202–219.