Relationship between diaphragm length and abdominal dimensions

We examined the relationship between changes in abdominal cross-sectional area, measured by respiratory inductive plethysmography, and changes in length in the costal and crural parts of the diaphragm, measured by sonomicrometry, in nine supine, anesthetized dogs. During passive inflation, both parts of the diaphragm shortened and abdominal cross-sectional area increased. During passive deflation, both parts of the diaphragm lengthened and abdominal cross-sectional area decreased. We subsequently used the relationship between costal and crural diaphragmatic length, respectively, and abdominal cross-sectional area during passive inflation-deflation to predict the length changes in the costal and crural diaphragm during quiet breathing before and after bilateral phrenicotomy. In the intact animal the inspiratory shortening in the crural diaphragm was almost invariably greater than predicted from the relationship during passive inflation. During inspiration after phrenicotomy the crural diaphragm invariably lengthened, whereas the costal diaphragm often shortened. In general there was a good correlation between the measured and predicted length change for the crural diaphragm (r = 0.72 before and 0.79 after phrenicotomy) and a poor one for the costal diaphragm (r = 0.05 before and 0.19 after phrenicotomy).     

Stomatal responses and water relations of Eucalyptus pauciflora in summer along an elevational gradient

Summary The spatial and temporal variation of lead conductance (g) in Eucalyptus pauciflora was analysed with respect to photon flux area density (I), temperature (T), water vapour concentration deficit (w), and leaf water potential () at four different sites between 940 m and 2,040 m altitude in the Snowy Mountains of south-eastern Australia. Along this altitudinal gradient the precipitation/evaporation ratio increases from 1 to 4. The results show that gas diffusion in this tree species is primarily controlled by I and w at all sites, independently of the specific soil moisture regime. Even under dry midsummer conditions with predawn leaf water potentials of-1 MPa at the lowest altitude, had no striking effect on g.The humidity threshold for the onset of stomatal closure does not vary greatly between the study sites (12.2±1.3 Pa kPa^-1). The highest and lowest values observed for , the osmotic potential at water saturation (from pressure/volume curves), the mean and maximum g and stomatal dentity, all increase with elevation. The highest (least negative) osmotic potentials were obtained at all sites in midsummer. It therefore appears that there is no osmotic adjustment to drought in the seasonal course. The maximum difference between osmotic potentials obtained at the lowest and highest sites is 0.46 MPa. In general osmotic potential varies less than has been reported for other plant species exposed to varying water regimes. This may be the consequence of the pronounced feed-forward response of the stomata to evaporative demand, which led to only moderate tissue desiccation, never exceeding the turgor loss point. E. pauciflora is a tree species with a very conservative utilisation of soil water, which adjusts to drought via stomatal control of water loss, rather than via osmotic properties.These results explain previous reports of the comparatively high susceptibility of E. pauciflora to severe drought and its positive influence on the hydrological balance of mountain ecosystems in the Australian Alps.     

Comparative Ontogenesis of Brain Tryptamine, Serotonin, and Tryptophan

The pattern of ontogenetic development of tryptophan (TP), tryptamine (T), indole-3-acetic acid (IAA), 5-hydroxytryptamine (5-HT; serotonin), and 5-hydroxyindole-3-acetic acid (5-HIAA) in the brains of rats aged 1-45 days is presented. Analysis of the five components in each brain allows the calculation of the acid/amine and amine/amino acid ratios. These metabolic indexes are a useful tool to study and compare the metabolic origins and fates of both amines. The ontogenetic patterns of TP, T, and IAA are very similar, especially during the first week postpartum. The highest and lowest levels found for T were 2.2 ng/g and 0.1 ng/g at the 1st and 5th day, respectively. The temporal relationship between the T/TP and IAA/T ratios suggests the existence of mechanisms protecting T against monoamine oxidase (MAO) which develop in parallel to synaptogenesis. Significant correlations were found between TP and IAA during the whole period studied and between TP and T during the first week after birth. The 5-HT peak found during the first postpartum week could be due to a non-neuronal pool of 5-HT protected against MAO and possibly contained in mast cells. Preliminary determinations on leptomeningeal membranes suggest the existence of such a pool.     

Sister chromatid differential staining and NOR activity of BrdU-resistant sublines

Summary Two 30 g/ml BrdU-resistant sublines and two 60 g/ml BrdU-resistant sublines are induced from a Chinese hamster cell line Wg3h (HGPRT^–) by one-step and two-step selections, respectively. By inoculating the cells into BrdU-free medium or by adding more BrdU into the culture medium for 26–27 h, it was found that the two BrdU-resistant sublines analysed have very clear sister chromatid differential (SCD) staining patterns. This indicates that some of the nuclear DNA of the BrdU-resistant cells incorporate with BrdU to reach a kinetic balance. Frequencies of sister chromatid exchange (SCE) of the resistant cells are twice to four times as high as those of the Wg3h cells, depending on which BrdU-resistant subline is analysed. The SCE frequencies of the resistant cells also increase with the BrdU concentration in the medium. Analysis of silver-stained nucleolar organizer regions (NORs) indicates that the NOR activity of three out of the four BrdU-resistant sublines is significantly suppressed, i.e., averages of the Ag-NOR number and number of the chromosomes bearing Ag-NORs per cell decrease significantly. The degree of suppression for different BrdU-resistant sublines may be quite different. The suppressed NOR activity of the resistant cells can gradually be restored when the cells are inoculated into BrdU-free medium, but the recovery speed is far lower than that of the Wg3h cells. The suppression of the NOR activity of the BrdU-resistant sublines should be due to BrdU toxicity.     

Histochemistry and ultrastructure of adrenergic and acetylcholinesterase-containing nerves supplying follicles and endocrine cells in the guinea-pig ovary

Summary With the use of an anti-human S-100 protein antibody, it was possible to reveal a characteristic cell type in the anterior lobe of the normal human pituitary. These cells, so-called folliculo-stellate cells, were present in all pituitaries studied but their number varied from one gland to another. Immunoreactive cells, isolated or grouped, were arranged close to various secretory granulated cells. Especially by use of double immunoenzymatic labeling, it was evident that these cells are spatially related either to somatotropes, prolactin cells and corticotropes, or to glycoprotein-containing cells. Such immunoreactive cells were rare or absent in pseudo-follicular arrangements of secretory granulated cells. Since it is now possible to identify this cell type by light microscopy and since no reliable functional significance is known, it seems more advisable to term this cell type stellate cell instead of folliculostellate cell.     

Heart structure and ventricular ultrastructure of hemoglobin- and myoglobin-free icefish Channichthys rhinoceratus

Summary The structural and ultrastructural characteristics of the heart of Channichthys rhinoceratus, an antarctic teleost devoid of respiratory pigments, are described and compared with those obtained from the red-blooded related species Notothenia rossii.The heart of the icefish is characterized by a spongy myocardium supplied with a highly developed arterial coronary system. This vasculature includes a subepicardial system and an extensive intratrabecular capillary network. Arterial hilar network and Thebesian vessels may also be present. The bulbus arteriosus shows unusually large spheroid structures located in the middle layer of the wall.Both white- and red-blooded species display comparable myocardial cell morphology and organelle distribution. However, the mitochondrial cristae of the former are more densely packed and the sarcolemma possesses numerous caveolae. A large proportion of non-contractile cells is also found in the icefish ventricular wall.     

Isolation of astrocytes,neurons, and synaptosomes of rat brain cortex

A simplified method was developed for the bulk separation of neuronal perikarya and astroglial celis from adult rat brain without the involvement of density gradients. Activities of various enzymes involved in glutamate metabolism were estimated and compared with those of synaptosomes. The activities of glutamate dehydrogenase and aspartate aminotransferase were higher in synaptosomes than in neuronal perikarya or glia. Glutamine synthetase was distributed in all the three fractions while glutaminase activity was higher in astrocytes than in synaptosomes and was not detectable in neuronal perikarya. The significance of these results in relation to metabolic compartmentation was discussed.     

ATF4在内质网应激调控成骨分化中的作用

为避免内质网中未折叠蛋白质的过度累积,真核细胞能激活一系列信号通路来维持内质网稳态,这个过程称为内质网应激。在骨生长发育中,适宜的内质网应激有助于成骨细胞、破骨细胞和软骨细胞的生长,可以促进骨髓间充质干细胞向成骨细胞分化。而过度的内质网应激会抑制成骨分化,严重的甚至导致骨质疏松、成骨不全等相关骨病的发生。内质网应激时可激活未折叠蛋白质反应,其主要是通过PERK/eIF2α/ATF4信号通路,上调转录激活因子4(ATF4)的表达。ATF4位于许多成骨分化调节因子的下游,是促进成骨分化的关键因子,在内质网应激对成骨分化的调节中发挥重要作用。在成骨分化过程中,适宜的内质网应激能通过激活PERK信号通路,诱导ATF4表达增加,进而上调骨钙素、骨涎蛋白等成骨所必需基因的表达,促进成骨分化。过度的内质网应激会激活ATF4/CHOP促凋亡途径,并导致Bax、胱天蛋白酶等凋亡信号分子的大量产生,进而导致细胞凋亡,抑制成骨分化。由于ATF4在ERS和成骨分化中的重要作用,ATF4在骨质疏松、成骨不全等骨相关疾病的治疗中具有重要意义。本文通过综述ATF4在内质网应激调控成骨分化中的作用机制,为相关骨性疾病治疗提供理论依据。     

Dose dependent responses of cattle to Theileria parva stabilate

Dolan T. T., Young A.S., Losos G.J., McMillan I., Minder Ch.E. and Soulsby K. 1984. Dose dependent responses of Theileria parva stabilate. International Journal for Parasitology14: 89–95. A tick derived stabilate of Theileria parva (Maguga) was titrated in a large group of Boran (Bos indicus) cattle of the same age, sex and origin. The infectivity data was analysed using the independent action model. The cattle were identified as heterogeneous in their response to infection with 75% showing one ID₅₀ (0.0014) and 25% showing another (0.01). The disease responses of the cattle given different dose levels were compared for a variety of parameters. The results obtained showed these parameters to be dose dependent including the time to onset of piroplasm parasitaemia. The stabilate is of large volume and can be used for controlled challenge in immunity studies and for comparison of susceptibility between cattle of different breeds and from different epidemiological backgrounds.     

Thyroid hormones modulate ornithine decarboxylase in the immature rat cerebellum

In this study, we measured ornithine decarboxylase (ODC) activity as a potential parameter to evaluate the response of the developing rat brain to thyroid hormones. In cerebellum, neonatal hyperthyroidism (40 micrograms thyroxine/100 g body weight daily from birth) increased ODC activity at 2 and 5 days of age and then accelerated its developmental decline. Conversely, ODC activity was decreased in 2- and 5-day-old hypothyroid rats (propylthiouracil to the mother), but it was not significantly different from normal thereafter. No significant differences were observed in the forebrain following either treatment. In hypothyroid rat cerebellum, a single injection of triiodothyronine (T3, 100 micrograms/100 g 18 h before sacrifice) increased significantly ODC activity at all ages. A dose-response study showed that 0.5 micrograms T3/100 g is sufficient to obtain maximal stimulation. Finally, administration of antiserum against rat growth hormone had no significant effect on ODC response to T3. These results show that ODC is a useful marker of thyroid state and tissue response in the neonatal rat cerebellum.