Mathematical simulation of the body fluid regulating system in dog

A mathematical model of body fluid volume and osmolality regulation was developed which incorporated the major nonlinearities of fluid assimilation, exchange, distribution and excretion. The non-linear differential equations define compartmental material balances for water, urea, sodium, protein and antidiuretic hormone (ADH). The parameters of these equations were calculated using analytical solutions and available steady-state experimental data. The model was used to simulate the renal response to five input forcings: (1) intraesophageal water infusion; (2) water ingestion; (3) intravenous ADH injection; (4) intravenous water infusion; and (5) intermittent water loading. The model yielded continuous simulation curves which agreed reasonably well with the available transient and steady-state experimental data. The model predicted that stimulating volume receptors via changes in left atrial pressure accounts for only 15–20% of changes in ADH secretion rate, whereas stimulation of the osmotic receptors via changes in plasma osmolality accounts for the remaining 80–85% of changes. Thus, it appears that regulation of ADH secretion is largely dependent upon plasma osmolality during forcings which do not appreciably alter the cardiovascular blood volume.     

Function of the Tetraspanin CD151–α6β1 Integrin Complex during Cellular Morphogenesis

Upon plating on basement membrane Matrigel, NIH3T3 cells formed an anastomosing network of cord-like structures, inhibitable by anti-alpha6beta1 integrin antibodies. For NIH3T3 cells transfected with human CD151 protein, the formation of a cord-like network was also inhibitable by anti-CD151 antibodies. Furthermore, CD151 and alpha6beta1 were physically associated within NIH3T3 cells. On removal of the short 8-amino acid C-terminal CD151 tail (by deletion or exchange), exogenous CD151 exerted a dominant negative effect, as it almost completely suppressed alpha6beta1-dependent cell network formation and NIH3T3 cell spreading on laminin-1 (an alpha6beta1 ligand). Importantly, mutant CD151 retained alpha6beta1 association and did not alter alpha6beta1-mediated cell adhesion to Matrigel. In conclusion, the CD151-alpha6beta1 integrin complex acts as a functional unit that markedly influences cellular morphogenesis, with the CD151 tail being of particular importance in determining the "outside-in" functions of alpha6beta1-integrin that follow ligand engagement. Also, antibodies to alpha6beta1 and CD151 inhibited formation of endothelial cell cord-like networks, thus pointing to possible relevance of CD151-alpha6beta1 complexes during angiogenesis.     

In vitro organogenesis of Citrus volkameriana and Citrus aurantium

In vitro organogenesis of Citrus volkameriana and C. aurantium was studied considering three explant types: epicotyl segment, internodal segment, and hypocotyl segment with attached cotyledon fragment. The explants were cultured in medium according to Grosser and Gmitter (EME) supplemented with 0, 0.5, 1.0, 1.5, and 2.0 mg dm^{− 3} 6-benzyl-aminopurine (BAP), incubated firstly in darkness for 4 weeks, and then transferred to 16-h photoperiod for 2 weeks. Comparing epicotyl and internodal segments, a higher percentage of responsive explants and a higher number of shoots per explant were obtained with epicotyl segments, regardless of the BAP concentration. For C. volkameriana the highest percentage of responsive epicotyl segments (42 %) was obtained in EME with 1.0 mg dm⁻³ BAP, while for C. aurantium (59 %) in EME with 0.5 mg dm⁻³ BAP. The organogenesis efficiency was the best with the use of the hypocotyl segment with attached cotyledon fragment (77 % for C. volkameriana and to 75 % for C. aurantium). With this explant the morphogenesis occurred only in the hypocotyl region. The in vitro organogenesis was characterized by histological analyses showing that the morphogenic process started in the cambium region near the explant cut end.     

A critical role for tetraspanin CD151 in alpha3beta1 and alpha6beta4 integrin-dependent tumor cell functions on laminin-5

The basement membrane protein laminin-5 supports tumor cell adhesion and motility and is implicated at multiple steps of the metastatic cascade. Tetraspanin CD151 engages in lateral, cell surface complexes with both of the major laminin-5 receptors, integrins alpha3beta1 and alpha6beta4. To determine the role of CD151 in tumor cell responses to laminin-5, we used retroviral RNA interference to efficiently silence CD151 expression in epidermal carcinoma cells. Near total loss of CD151 had no effect on steady state cell surface expression of alpha3beta1, alpha6beta4, or other integrins with which CD151 associates. However, CD151-silenced carcinoma cells displayed markedly impaired motility on laminin-5, accompanied by unusually persistent lateral and trailing edge adhesive contacts. CD151 silencing disrupted alpha3beta1 integrin association with tetraspanin-enriched microdomains, reduced the bulk detergent extractability of alpha3beta1, and impaired alpha3beta1 internalization in cells migrating on laminin-5. Both alpha3beta1- and alpha6beta4-dependent cell adhesion to laminin-5 were also impaired in CD151-silenced cells. Reexpressing CD151 in CD151-silenced cells reversed the adhesion and motility defects. Finally, loss of CD151 also impaired migration but not adhesion on substrates other than laminin-5. These data show that CD151 plays a critical role in tumor cell responses to laminin-5 and reveal promotion of integrin recycling as a novel potential mechanism whereby CD151 regulates tumor cell migration.     

<Emphasis Type="Italic">In vitro</Emphasis> organogenesis of <Emphasis Type="Italic">Passiflora alata</Emphasis>

Passiflora alata in vitro organogenesis was studied based on explant type, culture medium composition, and incubation conditions. The results indicated that the morphogenic process occurred more efficiently when hypocotyl segment-derived explants were cultured in media supplemented with cytokinin and AgNO₃ incubated under a 16-h photoperiod. The shoot bud elongation and plant development were obtained by transferring the material to MSM culture medium supplemented with GA₃ and incubated in flasks with vented lids. Histological analyses of the process revealed that the difficulties in obtaining plants could be related to the development of protuberances and leaf primordia structures, which did not contain shoot apical meristem. Roots developed easily by transferring elongated shoots to 1/2 MSM culture medium. Plant acclimatization occurred successfully, and somaclonal variation was not visually detected. The efficiency of this organogenesis protocol will be evaluated for genetic transformation of this species to obtain transgenic plants expressing genes that can influence the resistance to Cowpea aphid borne mosaic virus.     

Hematologic Values of Free-ranging Cebus cay and Cebus nigritus in Southern Brazil

We evaluated blood samples obtained from 80 free-ranging healthy capuchins (Cebus cay and C. nigritus) to establish hematological reference values and to assess the influence of sex and age on them. We caught the monkeys in the Paraná River region of Southern Brazil via manual or automatic traps. We anesthetized them intramuscularly with 3.6 mg/kg tiletamine/zolazepam hydrochlorides. After physical examinations, we divided the sample according to sex and age: 26 females (13 adults and 13 juveniles) and 54 males (27 adults and 27 juveniles). We collected blood and determined hematological values via traditional published methods. We analyzed data via 2-way ANOVA to test the effect of sex, age, and interactions between the 2 factors. The packed-cell volume was higher in adult males and the numbers of white blood cells and lymphocytes were higher in juveniles. There is no other significant difference.     

Electron microscopic study of teleost (Pimelodus maculatus) pancreatic islet cells

The endocrine pancreas of the freshwater teleost Pimelodus maculatus was studied by electron microscopy. Based on the granule morphology 2 cell types were described: Secretory granules of type I cells are rounded, nearly completely filling the limiting membranous sac which measures from 120 to 150 nm in diameter; the type II granules are also rounded and measure from 220 to 270 nm in diameter; they consist of an eccentrical electron dense core separated from the limiting membrane by a wide electron lucent halo. These characteristics are correlated with those found in other teleosts.