Importance of adenosine triphosphate in phospholipase A2-induced rabbit renal proximal tubule cell injury.

The pathogenesis of ischemic renal tubular cell injury involves a complex interaction of different processes, including membrane phospholipid alterations and depletion of high-energy phosphate stores. To assess the role of membrane phospholipid changes due to activation of phospholipases in renal tubule cell injury, suspensions enriched in rabbit renal proximal tubule segments were incubated with exogenous phospholipase A2 (PLA2). Exogenous PLA2 did not produce any significant change in various metabolic parameters reflective of cell injury in control nonhypoxic preparations despite a significant decrease in phosphatidylethanolamine (PE) and moderate increases in lysophosphatidylcholine (LPC) and lysophosphatidylethanolamine (LPE). In contrast, exogenous PLA2 treatment of hypoxic tubules resulted in a severe degree of cell injury, as demonstrated by marked declines in tubule K+ and ATP contents and significant decreases in tubule uncoupled respiratory rates, and was associated with significant phospholipid alterations, including marked declines in phosphatidylcholine (PC) and PE and significant rises in LPC, LPE, and free fatty acids (FFA). The injurious metabolic effects of exogenous PLA2 on hypoxic tubules were reversed by addition of ATP-MgCl2 to the tubules. The protective effect of ATP-MgCl2 was associated with increases in tubule PC and PE contents and declines in LPC, LPE, and FFA contents. These experiments thus indicate that an increase in exogenous PLA2 activity produces renal proximal tubule cell injury when cell ATP levels decline, at which point phospholipid resynthesis cannot keep pace with phospholipid degradation with resulting depletion of phospholipids and accumulation of lipid by-products. High-energy phosphate store depletion appears to be an important condition for exogenous PLA2 activity to induce renal tubule cell injury.     

兔跨室壁钙电流的性别差异

目的　研究雌、雄兔左室游离壁心内膜下心肌或中层心肌或心外膜下心肌L型钙电流 (ICa ,L)的分布。方法　全细胞膜片钳技术记录雌、雄兔 3层心肌ICa ,L 的分布和动作电位。结果　雌兔跨室壁复极离散较雄兔更显著 ,P <0 0 1。雌兔内、中、外 3层心肌细胞ICa,L密度分别为 (7 1± 0 6 )pA pF、 (10 4±0 9)pA pF和 (9 6± 1 1)pA pF ;雄兔则为 (9 1± 0 9)pA pF、 (10 5± 1 0 )pA/pF和 (9 8± 0 9)pA/pF。结论　雌兔跨室壁ICa ,L不均一性较雄兔明显 ,可能与雌兔易发生药物相关性TdP相关     

慢性支气管炎兔模型血气分析和血液流变学变化

目的探讨慢性支气管炎兔模型血气分析和血液流变学的变化。方法采用改良烟熏法复制慢性支气管炎兔模型,实验动物随机分为模型组、健康对照组（雌雄各半）。模型组以烟熏法喂养40d,对照组正常喂养40d后,抽取股动脉血进行血气分析和血液流变学的检测。结果模型组兔子的全血黏度（高、中、低切）、红细胞压积均明显升高（P〈0．05）,血浆黏度变化无明显差异;模型组的pH无变化,PO2,PCO2,SaO2％有显著性变化：PO2有明显下降（P〈0．01）,PCO2、SaO2％明显上升（P〈0．05）。结论模型组存在低氧血症、高碳酸血症及高黏、高聚的血液流变学特点。     

Interleukin-2-induced dermatotoxicity resembling toxic epidermal necrolysis.

Interleukin-2 is a promising new immunotherapeutic antineoplastic agent, but it can cause severe multiorgan toxicity. Although dermatologic toxicity is seen in most patients receiving IL-2 therapy, it is usually manifested as pruritus and an erythematous macular rash, which resolve quickly once infusion is terminated. We have described a patient who was allergic to multiple drugs and who had sloughing of large sheets of epidermis over 75% of body surface area during IL-2 therapy. Clinically, this was indistinguishable from toxic epidermal necrolysis, but the findings on skin biopsy were nonspecific for any dermatitides. The skin healed after cessation of IL-2 infusion, but the rash recurred upon resuming infusion at a lesser dose, indicting IL-2 as the probable causative agent. This unique dermatologic sensitivity to IL-2 suggests that IL-2 could act directly as a promoter in dermatologic disease. Patients with a history of allergic reactions to other unrelated drugs should be monitored carefully for unusual bullous dermatologic changes during IL-2 therapy.     

Effects of pulsed versus conventional radiofrequency current on rabbit dorsal root ganglion morphology.

Lesioning using radiofrequency (RF) current has been increasingly used in clinical practice for the treatment of pain syndromes. Although formation of heat causing "thermocoagulation" of the nervous tissues is thought to be responsible of the clinical outcome, a more recent modality of RF application named pulsed radiofrequency (PRF) delivers the RF current without producing destructive levels of heat. In our study, we compared the effects of conventional RF (CRF) and PRF on rabbit dorsal root ganglion (DRG) morphology, including also control and sham operated groups. The setting of the experiment and the RF parameters used were similar to those used in current clinical practice. The specimens were analyzed both with light microscopy and electron microscopy, two weeks after the procedure. At the light microscopic level, all groups had preserved the normal DRG morphology and no differences were observed between them. In the electron microscopic analysis there were no pathological findings in the control and sham operated groups. But the ganglion cells in the RF groups had enlarged endoplasmic reticulum cisterns and increased number of cytoplasmic vacuoles which were more evident in the CRF group. Some of the ganglion cells in the CRF group had mitochondrial degeneration, nuclear membrane disorders or loss of nuclear membrane and neurolemma integrity. The myelinated and unmyelinated nerve fibers were of normal morphology in all groups. Our results suggest that PRF application is less destructive of cellular morphology than CRF at clinically used "doses". Before making certain judgements, more experimental and clinical studies should be planned.     

Platelet activating factor mediates interleukin-2-induced lung injury in the rat.

Interleukin-2 was recently shown to cause acute lung injury characterized by microvascular permeability defect, interstitial edema, and leukosequestration. Similar responses can also be produced by platelet activating factor (PAF). Thus, the present study aimed to examine whether PAF plays a key role in the development of IL-2-induced lung injury in the anesthetized rat. Intravenous infusion (60 min) of recombinant human IL-2 at 10(5)-10(6) U/rat (n = 7-9) dose-dependently elevated lung water content (27 +/- 1%, P less than 0.01), myeloperoxidase activity (+84 +/- 23%, P less than 0.05), and serum thromboxane B2 (990 +/- 70%, P less than 0.01), but failed to alter blood pressure, hematocrit, serum tumor necrosis factor-alpha, and circulating leukocytes and platelets. Pretreatment (-30 min) with a potent and specific PAF antagonist, BN 50739 (10 mg/kg, intraperitoneally, n = 6) prevented the pulmonary edema (P less than 0.05) and thromboxane B2 production (P less than 0.01), and attenuated the elevation of lung myeloperoxidase activity (+18 +/- 16%, P less than 0.05) induced by IL-2. These data suggest that PAF is involved in the pathophysiological processes leading to IL-2-induced lung injury, and point to the potential therapeutic capacity of PAF antagonists in preventing pulmonary edema during IL-2 therapy.     

Nitric oxide amplifies interleukin 1-induced cyclooxygenase-2 expression in rat mesangial cells.

Interleukin 1 and nitric oxide (NO) from infiltrating macrophages and activated mesangial cells may act in concert to sustain and promote glomerular damage. To evaluate if such synergy occurs, we evaluated the effect if IL-1 beta and NO on the formation of prostaglandin (PG)E2 and cyclooxygenase (COX) expression. The NO donors, sodium nitroprusside and S-nitroso-N-acetylpenicillamine, alone did not increase basal PGE2 formation. However, these compounds amplified IL-1 beta-induced PGE2 production. Similarly, sodium nitroprusside and S-nitroso-N-acetylpenicillamine by themselves did not induce mRNA and protein for COX-2, the inducible isoform of COX; however, they both potentiated IL-1 beta-induced mRNA and protein expression of COX-2. The stimulatory effect of NO is likely to be mediated by cGMP since (a) an inhibitor of the soluble guanylate cyclase, methylene blue, reversed the stimulatory effect of NO donors on COX-2 mRNA expression; (b) the membrane-permeable cGMP analogue, 8-Br-cGMP, mimicked the stimulatory effect of NO donors on COX-2-mRNA expression; and (c) atrial natriuretic peptide, which increases cellular cGMP by activating the membrane-bound guanylate cyclase, also amplified IL-1 beta-induced COX-2 mRNA expression. These data indicate a novel interaction between NO and COX pathways.     

Interleukin-2-induced chemotaxis of human T-lymphocytes

Interleukin-2 (IL-2), a growth factor for T-lymphocytes, has been postulated to cause the accumulation of T-lymphocytes at sites of inflammation by inducing proliferation of these cells. We hypothesized that IL-2 might also serve to attract T-lymphocytes to inflammatory sites. To test this hypothesis, human T-lymphocytes were purified from the peripheral blood of normal volunteers by rosetting with neuraminidase-treated sheep red blood cells and tested for chemotactic activity by using a blind-well chamber technique. Purified IL-2 caused a greater than 20-fold attraction of T-lymphocytes compared with medium alone (P less than 0.001). This attraction was shown to be chemotactic rather than chemokinetic by checkerboard analysis. The T-lymphocyte chemotaxis could be completely inhibited by adsorption of the IL-2 with an IL-2-dependent cell line, and could be neutralized by monoclonal anti-IL-2 antibody. Further specificity of IL-2-directed chemotaxis was demonstrated by using species-specific IL-2. Mouse IL-2 was ineffective at promoting human T-lymphocyte chemotaxis. These data suggest that IL-2 may be responsible for the localized accumulation of T-lymphocytes both by causing attraction of these cells and by modulating their proliferation.     

CRTH2受体的磷酸化在PGD2诱导的哮喘中的作用

目的探讨前列腺素D2（ProstaglandinD2,PGD2）诱导外周血淋巴细胞表面前列腺素受体（CRTH2）功能状态变化的信号转导通路与该受体磷酸化的关系,以进一步阐明哮喘的发病机制。方法利用磷酸化蛋白提取试剂盒获得目的蛋白,利用Western blot技术检测用PGD2刺激后淋巴细胞表面CRTH2受体的表达情况及磷酸化的程度。结果用PGD2刺激后淋巴细胞表面CRTH2受体表达量明显下调、CRTH2受体的磷酸化程度明显提高、淋巴细胞表面CD40L的表达上调。结论CRTH2受体在正常人存在微弱的磷酸化现象,在用PGD2刺激后CRTH2受体磷酸化的水平增高。表明CRTH2受体主要是通过磷酸化和去磷酸化作用来调节PGD2所介导的信号转导,同时CRTH2磷酸化能够导致Th2细胞活化。     

Appraising current therapy for breast cancer. 2. Irradiation.

The best combination of methods for managing primary breast cancer may not yet be known. Radiation therapy has been proved effective in decreasing the incidence of local and regional recurrence following mastectomy. Thus, until a superior regimen is established, I recommend local and regional irradiation for patients at high risk for recurrence. Local irradiation is also an effective means of achieving palliation of symptoms associated with metastatic disease.     

Novel interleukin 2 (IL-2) receptor appears to mediate IL-2-induced activation of natural killer cells.

A novel IL-2 receptor, distinct from the Tac protein, has been identified on the surface of purified human natural killer (NK) cells by chemical cross-linking of 125I-IL-2. This protein is approximately 70,000 D in size (p70) and appears to be identical to the recently recognized second subunit of the human high affinity IL-2 receptor complex. Scatchard analysis of 125I-IL-2 binding to purified NK cells revealed approximately 2,300 p70 binding sites per cell with an apparent dissociation constant of 200 pM, a value intermediate between the previously recognized high and low affinity forms of the human IL-2 receptor. The monoclonal anti-Tac antibody did not inhibit the cross-linking of 125I-IL-2 to the p70 binding sites present on NK cells. Functionally, the addition of high concentrations of recombinant IL-2 to the enriched NK cells promoted a rapid augmentation of cytolytic activity and a more delayed increase in cellular proliferation. Anti-Tac effectively blocked the IL-2-induced proliferative response in these cells, but failed to alter the enhancement of cytotoxicity. Analysis of NK cytoplasmic RNA isolated at various time points after IL-2 stimulation revealed the rapid induction of c-myb and Tac gene expression that was also not inhibited by the anti-Tac antibody. These findings suggest that IL-2 binding to the p70 receptor constitutively expressed on the surface of NK cells may mediate both the development of increased cytolytic activity and rapid changes in gene expression. The activation of the Tac gene may in turn permit the formation of the high affinity IL-2 receptor complex (comprised of at least the Tac and p70 proteins) that appears to transduce the requisite signals involved in NK cell proliferation.