Intercellular communication in the rat anterior pituitary gland: an in vivo and in vitro study

The concept of "stimulus-secretion coupling" suggested by Douglas and co-workers to explain the events related to monamine discharge by the adrenal medulla (5, 7) may be applied to other endocrine tissues, such as adrenal cortex (36), pancreatic islets (4), and magnocellular hypothalamic neurons (6), which exhibit a similar ion-dependent process of hormone elaboration. In addition, they share another feature, that of joining neighbor cells via membrane junctions (12, 26, and Fletcher, unpublished observation). Given this, and the reports that hormone secretion by the pars distalis also involves a secretagogue-induced decrease in membrane bioelectric potential accompanied by a rise in cellular [Ca++] (27, 34, 41), it was appropriate to test the possibility that cells of the anterior pituitary gland are united by junctions.     

Interaction of a non-peptide agonist with angiotensin II AT1 receptor mutants

To identify residues of the rat AT1A angiotensin II receptor involved with signal transduction and binding of the non-peptide agonist L-162,313 (5,7-dimethyl-2-ethyl-3-[[4-[2(n-butyloxycarbonylsulfonamido)-5-isobutyl-3-thienyl]phenyl]methyl]imidazol[4,5,6]-pyridine) we have performed ligand binding and inositol phosphate turnover assays in COS-7 cells transiently transfected with the wild-type and mutant forms of the receptor. Mutant receptors bore modifications in the extracellular region: T88H, Y92H, G1961, G196W, and D278E. Compound L-162,313 displaced [125I]-Sar1,Leu8-AngII from the mutants G196I and G196W with IC50 values similar to that of the wild-type. The affinity was, however, slightly affected by the D278E mutation and more significantly by the T88H and Y92H mutations. In inositol phosphate turnover assays, the ability of L-162,313 to trigger the activation cascade was compared with that of angiotensin II. These assays showed that the G196W mutant reached a relative maximum activation exceeding that of the wild-type receptor; the efficacy was slightly reduced in the G1961 mutant and further reduced in the T88H, Y92H, and D278E mutants. Our data suggest that residues of the extracellular domain of the AT1 receptor are involved in the binding of the non-peptide ligand, or in a general receptor activation phenomenon that involves conformational modifications for a preferential binding of agonists or antagonists.     

Proteomic analysis reveals alterations in the renal kallikrein pathway during hypoxia-induced hypertension

Obstructive sleep apnea syndrome (OSAS), a disorder characterized by episodic hypoxia (EH) during sleep, is associated with systemic hypertension. We used proteomic analysis to examine differences in rat kidney protein expression during EH, and their potential relationship to EH-induced hypertension. Young male Sprague-Dawley rats were exposed to either EH or sustained hypoxia (SH) for 14 (EH14/SH14) and 30 (EH30/SH30) days. Mean arterial blood pressure was significantly increased only in EH30 (p < 0.0002). Kidney proteins were resolved by two-dimensional-PAGE and were identified by MALDI-MS. Renal expression of kallistatin, a potent vasodilator, was down-regulated in all animals. Expression of alpha-1-antitrypsin, an inhibitor of kallikrein activation, was up-regulated in EH but down-regulated in SH. Western blotting showed significant elevation of B(2)-bradykinin receptor expression in all normotensive animals but remained unchanged in hypertensive animals. Proteins relevant to vascular hypertrophy, such as smooth muscle myosin and protein-disulfide isomerase were up-regulated in EH30 but were down-regulated in SH30. These data indicate that EH induces changes in renal protein expression consistent with impairment of vasodilation mediated by the kallikrein-kallistatin pathway and vascular hypertrophy. In contrast, SH-induced changes suggest the kallikrein- and bradykinin-mediated compensatory mechanisms for prevention of hypertension and vascular remodeling. To test the hypothesis suggested by the proteomic data, we measured the effect of EH on blood pressure in transgenic hKLK1 rats that overexpress human kallikrein. Transgenic hKLK1 animals were protected from EH-induced hypertension. We conclude that EH-induced hypertension may result, at least in part, from altered regulation of the renal kallikrein system.     

Natural products as starting points for future anti-malarial therapies: going back to our roots?

Background

Population movements along the Thailand-Cambodia border, particularly among highly mobile and hard-to-access migrant groups from Cambodia and Myanmar, are assumed to play a key role in the spread of artemisinin resistance. Data on treatment-seeking behaviours, knowledge and perceptions about malaria, and use of preventive measures is lacking as characteristics of this population prevent them from being represented in routine surveillance and the lack of a sampling frame makes reliable surveys challenging.

Methods

A survey of migrant populations from Cambodia and Myanmar was implemented in five selected rural locations in Thailand along the Thai-Cambodian border using respondent driven sampling (RDS) to determine demographic characteristics of the population, migratory patterns, knowledge about malaria, and health-care -seeking behaviours.

Results

The majority of migrants from Myanmar are long-term residents (98%) with no plans to move back to Myanmar, understand spoken Thai (77%) and can therefore benefit from health messages in Thai, have Thai health insurance (99%) and accessed public health services in Thailand (63%) for their last illness. In comparison, the majority of Cambodian migrants are short-term (72%). Of the short-term Cambodian migrants, 92% work in agriculture, 18% speak Thai, 3.4% have Thai health insurance, and the majority returned to Cambodia for treatment (45%), self-treated (11%), or did not seek treatment for their last illness (27%).

Conclusion

Most highly mobile migrants along the Thai-Cambodia border are not accessing health messages or health treatment in Thailand, increasing their risk of malaria and facilitating the spread of potentially resistant Plasmodium falciparum as they return to Cambodia to seek treatment. Reaching out to highly mobile migrants with health messaging they can understand and malaria diagnosis and treatment services they can access is imperative in the effort to contain the spread of artemisinin-resistant P. falciparum.     

Airway cellularity, lipid laden macrophages and microbiology of gastric juice and airways in children with reflux oesophagitis

Background and methods

Human metapneumovirus (hMPV) is a recently discovered respiratory virus associated with bronchiolitis, pneumonia, croup and exacerbations of asthma. Since respiratory viruses are frequently detected in patients with acute exacerbations of COPD (AE-COPD) it was our aim to investigate the frequency of hMPV detection in a prospective cohort of hospitalized patients with AE-COPD compared to patients with stable COPD and to smokers without by means of quantitative real-time RT-PCR.

Results

We analysed nasal lavage and induced sputum of 130 patients with AE-COPD, 65 patients with stable COPD and 34 smokers without COPD. HMPV was detected in 3/130 (2.3%) AE-COPD patients with a mean of 6.5 × 10⁵ viral copies/ml in nasal lavage and 1.88 × 10⁵ viral copies/ml in induced sputum. It was not found in patients with stable COPD or smokers without COPD.

Conclusion

HMPV is only found in a very small number of patients with AE-COPD. However it should be considered as a further possible viral trigger of AE-COPD because asymptomatic carriage is unlikely.     

Interplay between parasite cysteine proteases and the host kinin system modulates microvascular leakage and macrophage infection by promastigotes of the Leishmania donovani complex

Kinins, the vasoactive peptides proteolytically liberated from kininogens, were recently recognized as signals alerting the innate immune system. Here we demonstrate that Leishmania donovani and Leishmania chagasi, two etiological agents of visceral leishmaniasis (VL), activate the kinin system. Intravital microscopy in the hamster cheek pouch showed that topically applied promastigotes induced macromolecular leakage (FITC-dextran) through postcapillary venules. Peaking at 15 min, the parasite-induced leakage was drastically enhanced by captopril (Cap), an inhibitor of angiotensin-converting enzyme (ACE), a kinin-degrading metallopeptidase. The enhanced microvascular responses were cancelled by HOE-140, an antagonist of the B2 bradykinin receptor (B2R), or by pre-treatment of promastigotes with the irreversible cysteine proteinase inhibitor N-methylpiperazine-urea-Phe-homoPhe-vinylsulfone-benzene (N-Pip-hF-VSPh). In agreement with the above-mentioned data, the promastigotes vigorously induced edema in the paw of Cap-treated J129 mice, but not Cap-B2R-/- mice. Analysis of parasite-induced breakdown of high molecular weight kininogens (HK), combined with active site-affinity-labeling with biotin-N-Pip-hF-VSPh, identified 35-40 kDa proteins as kinin-releasing cysteine peptidases. We then checked if macrophage infectivity was influenced by interplay between these kinin-releasing parasite proteases, kininogens, and kinin-degrading peptidases (i.e. ACE). Our studies revealed that full-fledged B2R engagement resulted in vigorous increase of L. chagasi uptake by resident macrophages. Evidence that inflammatory macrophages treated with HOE-140 became highly susceptible to amastigote outgrowth, assessed 72 h after initial macrophage interaction, further suggests that the kinin/B2R activation pathway may critically modulate inflammation and innate immunity in visceral leishmaniasis.     

植物的遗传转化及其应用(英文)

近年来,植物遗传转化研究有了长足的发展。已经达到能够通过简单的遗传控制手段研究具有新表现型的植物,甚至达到进入商业化的程度。这些手段包括植物生物学的主要研究技术以及植物组织培养和树种改良的一些实用方法。尽管采用农瘤杆菌和鸟枪法等技术的植物遗传转化系统已经得到了广泛的应用,但是在如何开发具有能够得到控制表达的转基因高产植物方面,在如何使所得到的转基因植物远离遗传危害等方面,目前的转化系统遇到了极大的技术挑战。已经提出了各种各样的方法用于将新基因稳定地导入120多种不同植物的核基因组。本文将讨论这些遗传转化系统所需的生物学要求和实际应用方面的需求、基因转化和转基因表达的研究策略、遗传转化植物的鉴定以及转基因植物与大众的认可。本文将分为七个部分加以讨论:一、导言;二 、基因转化到细胞里的方法;三、植物遗传转化策略;四、植物遗传转化的鉴定;五、植物遗传转化的实际应用;六、转基因植物与环境;七、未来植物遗传转化的需求与发展方向。     

Skeletal modification by microorganisms and their environments

Abstract

Microstructural post mortem changes to skeletal tissues by microorganisms are driven by several factors including the death history of an animal, its decomposition trajectory, and the depositing environment itself. The study we describe here brings together material from recent and fossil contexts that are depositionally distinct from a terrestrial-marine transitionary shoreline environment. We compare these changes with those of marine environments previously identified in the Mary Rose material, and those of continental waters (lakes) previously identified in the Cerro de la Garita (Concud) site, and we document this against bacterially related changes observed from terrestrial contexts. A new microstructural change identified in material from terrestrial sites is also described relating to rootlet damage. By considering microstructural change in skeletal tissues, it is maybe possible to ascribe environmental context, or, to better understand the complexity of material presented by transitionary environments.     

Ants in a hospital environment and its importance as vector of bacteria

The external ant community of Hospital Municipal de Morrinhos, in Morrinhos, Goiás State, was characterized by the low rates of richness, diversity, dominance and equity of species abundance. Pheidole sp.1, a polygynic species was numerically dominant in this environment, although it coexists with potentially competitive species. This ant species prevailed within all hospital departments and its space-time distribution was a little aggregated (variance/mean ratio = 1.102, chi2 = 29.38, P < 0.01). Escherichia, Salmonella, Aeromonas, Enterococcus, Staphylococcus and Klebsiella were the bacteria associated to this ant species in nearly all hospital annexes. The unicolonialism of Pheidole sp.1 tends to increase the contamination and dissemination process of infecto-contagious agents. The control and management of this ant species must be followed by practices that reduce the colonization process by other queens and the quantity of site nidification within the hospital.     

The non-peptide kinin receptor antagonists FR 173657 and SSR 240612: preclinical evidence for the treatment of skin inflammation

Peptide and non-peptide kinin receptor antagonists were evaluated in cutaneous inflammation models in mice. Topical and i.p. application of kinin B(1) and B(2) receptor antagonists caused a significant inhibition of the capsaicin-induced cutaneous neurogenic inflammatory response. The calculated mean ID(50) for Hoe140 and SSR240612 were 23.83 (9.14-62.14) nmol/kg and 0.23 (0.15-0.36) mg/ear, respectively. The I(max) observed for Hoe140, SSR240612, R-715, FR173657, and FR plus SSR were 61+/-5%, 56+/-3%, 65+/-10%, 48+/-8%, and 52+/-4%, respectively. Supporting these results, double B(1) and B(2) kinin receptors knockout mice showed a significant inhibition of capsaicin-induced ear oedema (42+/-7%). However, mice with a single deletion of either B(1) or B(2) receptors exhibited no change in their capsaicin responses. In contrast, all of the examined kinin receptor antagonists were unable to inhibit the oedema induced by TPA and the results from knockout mice confirmed the lack of kinin receptor signaling in this model. These findings show that kinin receptors are present in the skin and that both kinin receptors seem to be important in the neurogenic inflammatory response. Moreover, non-peptide antagonists were very effective in reducing skin inflammation when topically applied, thereby suggesting that they could be useful tools in the treatment of some skin inflammatory diseases.