Effects of hypophysectomy and thyroidectomy on salt balance in the plethodontid salamanders,Desmognathus fuscus andDesmognathus monticola

Summary Hypophysectomy significantly reduced serum sodium levels inDesmognathus fuscus andD. monticola. Prolactin, corticosterone or aldosterone replacement failed to restore serum sodium to control levels. Hypophysectomy also led to decreases in in vitro integumental potential difference and shortcircuit current, which were not restored to control levels by prolactin or corticosterone. Thyroidectomy significantly reduced the level of serum sodium inD. monticola, but it increased in vitro potential difference and short-circuit current. Thyroxine treatment of either hypophysectomized or thyroidectomizedD. monticola completely restored serum sodium, potential difference and short-circuite current to control levels.     

SOME SURFACE CHARACTERISTICS OF THE CHLOROPLAST ENVELOPE

Pronase, cationic ferritin, and ferritin-conjugated plant lectins were used to study the chloroplast envelope. Negative charges (binding cationic ferritin) are fairly uniformly distributed over the envelope surfaces in contact with the hyaloplasm and are not appreciably altered by mild pronase treatment of isolated plastids. All surfaces of stroma-free thylakoids previously exposed to the stroma uniformly bind cationic ferritin. Ricin_II-ferritin binding to the membranes of the chloroplast envelope indicates that galactolipids are distributed in the outer membrane in such a way that their galactose moieties are exposed on the envelope surface. In addition, the outer surface of the inner membrane (the intermembrane face) contains uniformly distributed galactose which binds ricin_II when this membrane is exposed to the reaction medium. Isolated vesicles of the chloroplast envelope bind ricin_II, while isolated envelope vesicles as well as the envelopes of intact chloroplasts failed to bind concanavalin A. Thylakoid surfaces showed minor binding of ricin_II as well as concanavalin A.     

Are flowers physiological sinks or faucets? Costs and correlates of water use by flowers of Polemonium viscosum

Water loss through inflorescences may place extreme demands on plant water status in arid environments. Here we examine how corolla size, a trait known to influence pollination success, affects the water cost of flowering in the alpine skypilot, Polemonium viscosum. In a potometry experiment, water uptake rates of inflorescences were monitored during bud expansion and anthesis. Corolla volume of fully expanded flowers predicted water uptake during bud expansion (R ²=0.61, P=0.0375) and corolla surface area predicted water uptake during anthesis (R ²=0.59, P=0.044). To probe mechanisms underlying the relationship between corolla size and water uptake, cell dimensions and densities were measured in several regions of fully expanded corollas. Corolla length was positively correlated with cell length in the middle of the corolla tube and cell diameter in the corolla lobe (Pearson's r from 0.26–0.33, n=86, P ≤ 0.05). Cell density was negatively correlated with cell dimensions in the upper corolla tube and lobe (Pearson's r from –0.39 to –0.42, P ≤ 0.0015). These findings suggest that more water may be required to maintain turgor in large corollas in part because their tissues have lower cell wall densities. The carbon cost of water use by flowers was assessed in krummholz and tundra habitats for P. viscosum flowering, respectively, during dry and wet portions of the growing season. For plants in full flower, average leaf water potentials were significantly more negative (P=0.0079) at mid-day in the krummholz (June) than in the tundra (July), but were similar before dawn (P=0.631). Photosynthetic rate at the time of flowering declined significantly with increasing corolla size in the krummholz (P=0.0376), but was unrelated to corolla size on the tundra (P>0.72). Plants losing water through large corollas may close leaf stomata to maintain turgor. If photosynthesis limits growth in this perennial species, then the water cost of producing large flowers should exacerbate the cost of reproduction under dry conditions. Such factors could select for flowers with smaller corollas in the krummholz, countering pollinator-mediated selection and helping maintain genetic variation in corolla size components of P. viscosum. Received: 5 May 1998 / Accepted: 2 October 1998     

Expression and functional implications of CCR2 expression on murine alveolar epithelial cells

Acute lung injury results in damage to the alveolar epithelium, leading to leak of proteins into the alveolar space and impaired gas exchange. Lung function can be restored only if the epithelial layer is restored. The process of reepithelialization requires migration of lung epithelial cells to cover denuded basement membranes. The factors that control the migration of lung epithelial cells are incompletely understood. We examined isolated murine type II alveolar epithelial cells (AECs) for expression of CC chemokine receptor 2 (CCR2) and functional consequences of the binding of the main CCR2 ligand monocyte chemoattractant protein-1 (MCP-1). We found that primary AECs bound MCP-1 and expressed CCR2 mRNA. These cells demonstrated functional consequences of CCR2 expression with migration in response to MCP-1 in chemotaxis/haptotaxis assays. Primary AECs cultured from mice lacking CCR2 did not respond to MCP-1. Monolayers of AECs lacking CCR2 demonstrated delayed closure of mechanical wounds compared with AEC monolayers expressing CCR2. Delayed closure of mechanical wounds of wild-type AECs was also demonstrated in the presence of anti-MCP-1 antibody. These data demonstrate for the first time that AECs express CCR2 and are capable of using this receptor for chemotaxis and healing of wounds. CCR2-MCP-1 interactions may be important in the process of reepithelialization after lung injury.     

Chemotaxis inhibitory protein of Staphylococcus aureus binds specifically to the C5a and formylated peptide receptor

Chemotaxis inhibitory protein of Staphylococcus aureus (CHIPS) is an exoprotein produced by several strains of S. aureus, and a potent inhibitor of neutrophil and monocyte chemotaxis toward C5a and formylated peptides like fMLP. These chemoattractants act on their target cells by binding and activating the C5aR and formylated peptide receptor (FPR), respectively. In the present report, we examined the mechanism by which CHIPS affects both of these receptors. We showed that CHIPS blocked binding of anti-C5aR mAb and formylated peptide to human neutrophils as efficiently at temperatures of 0 and 37 degrees C, implying that it is independent of signal transducing systems. This was confirmed by showing that CHIPS acts completely independently of ATP. Additionally, CHIPS was not internalized upon binding to neutrophils. Furthermore, we showed that CHIPS binds specifically to the C5aR and FPR expressed on U937 cells. This binding was functional in blocking C5a- and fMLP-induced calcium mobilization in these cell lines. These results suggest that CHIPS binds directly to the C5aR and FPR, thereby preventing the natural ligands from activating these receptors. The apparent K(d) values of CHIPS for the C5aR and FPR were 1.1 +/- 0.2 nM and 35.4 +/- 7.7 nM, respectively. Moreover, after screening a wide variety of other G protein-coupled receptors, CHIPS was found to affect exclusively the C5aR and FPR. This selectivity and high-affinity binding with potent antagonistic effects makes CHIPS a promising lead for the development of new anti-inflammatory compounds for diseases in which damage by neutrophils plays a key role.     

Protection from fluorescein isothiocyanate-induced fibrosis in IL-13-deficient, but not IL-4-deficient, mice results from impaired collagen synthesis by fibroblasts

Intratracheal injection of FITC results in acute lung injury and progresses to fibrosis by day 21 postchallenge. In response to FITC, BALB/c mice produce IL-4 and IL-13 in the lung. To investigate whether IL-4 and/or IL-13 were important profibrotic mediators in this model, we examined the fibrotic response to FITC in mice that were genetically deficient in IL-4 (IL-4(-/-)), IL-13 (IL-13(-/-)), or IL-4 and IL-13 combined (IL-4/13(-/-)). Baseline levels of collagen were similar in all mice. In response to FITC, both BALB/c and IL-4(-/-) mice developed fibrosis, whereas the IL-13(-/-) and IL-4/13(-/-) mice were significantly protected, as measured by total lung collagen levels and histology. Total leukocyte recruitment to the lung was similar in all four strains of mice when measured on days 7, 14, and 21 post-FITC. BALB/c mice showed prominent eosinophilia on day 7 that was absent in IL-4(-/-), IL-13(-/-), and IL-4/13(-/-) mice, suggesting that eosinophilia is not necessary for development of a fibrotic response. There were no significant differences in the percentages of any other leukocytes analyzed between the genotypes. Similarly, protection in IL-13(-/-) mice was not associated with alterations in cytokine or eicosanoid profiles. Interestingly, TGF-beta1 production was not reduced in IL-13(-/-) mice. Analyses of fibroblasts isolated from the four genotypes demonstrated that although there were similar numbers of fibroblasts present in cultures of lung minces, fibroblasts from IL-13-deficient strains have reduced basal and stimulated levels of collagen production. IL-13Ralpha1 expression increases on fibroblasts during fibrotic responses in vivo, and IL-13 increases collagen synthesis in fibroblasts. Thus, IL-13 mediates its profibrotic actions through direct effects on fibroblast production of extracellular matrix.     

Herpes zoster as a rare complication of liposuction

Liposuction typically has a low incidence of complications and is associated with significant cosmetic benefit. In this case, the patient developed a dermatomal rash with vesicles on an erythematous base consistent with herpes zoster 8 days after liposuction to the back and flanks. To the authors' knowledge, herpes zoster has not been previously reported as a complication of liposuction. Although the precise relationship of herpes zoster infection to the liposuction procedure is difficult to determine, mechanical irritation most likely reactivated the varicella zoster virus in the involved dermatomal distribution. The patient was treated with antiviral and analgesic medications and healed without any further complications.