甲基莲心碱对豚鼠心房生理特性及异丙肾上腺素和Ca2+量—效反应的影响

甲基莲心碱1～100μmol/L浓度依赖性地抑制豚鼠左心房收缩性,延长功能性不应期,降低兴奋性;30μmol/L甲基莲心碱能明显提高肾上腺素诱发左心房自律性的阈浓度。对异丙肾上腺素量—效反应的影响,不同于β-受体阻滞剂普萘洛尔,表现为非竞争性拮抗作用,对Ca²⁺量—效反应的影响,与抗钙剂维拉帕米类似,呈竞争性和非竞争性双重拮抗作用。     

Grade I hydronephrosis: pulsed Doppler US evaluation

This study was undertaken to determine whether the presence of blood vessels could mimic the appearance of grade I hydronephrosis on sonograms and thus cause false-positive readings. One hundred consecutive patients with grade I hydronephrosis were examined. Sample volumes were obtained with pulsed Doppler ultrasonography (US) at the site of the greatest separation of the central renal sinus echoes to determine if the separation was fluid accumulating in the collecting system, as in obstruction, or if the separation was actually caused by vessels that mimic hydronephrosis. Vascular structures accounted for the separation of the sinus echoes in 43% of patients. In patients 12 years of age or younger, this frequency rose to 61%. The simple procedure of evaluating the renal sinus echo separation with pulsed Doppler US should decrease the frequency of false-positive diagnoses of hydronephrosis and thus diminish the need for further confirmatory testing.     

Acute and long-term effects of massive balloon dilation on the aortic wall and vasa vasorum

To investigate the acute and long-term effects on the vasa vasorum after massive overdilation, canine aortic segments were dilated with Gruentzig balloon catheters to more than 100% over normal size. In the acute study, the significant lumen increase was the result of intimal and medial rupture with stretching and thinning of the adventitia. In these areas, the vasa vasorum were stretched and severed, causing adventitial hemorrhage. In the chronic study, areas of previous subtotal wall rupture with adventitial thinning were repaired by scar tissue. This repair included formation of a neomedia, hyperplasia of the adventitia, and proliferation of the vasa vasorum. No progression of luminal dilatation was seen. This study showed that in subtotal aortic wall rupture, even a severely damaged adventitia is capable of preserving the lumen from further dilatation and rupture until healing. Blood flow to the damaged vessel wall was reestablished by revascularization via capillary budding in the aortic wall.     

Influence of CT on radiologic utilization in The Netherlands

The authors studied the influence of computed tomography (CT) on radiologic utilization in The Netherlands. Twenty-six hospitals with a CT scanner were compared with 27 hospitals without on the basis of number of radiologic procedures per clinical patient from 1977 to 1984. Changes in average length of hospitalization were also considered. The number of procedures decreased in hospitals with CT scanners (-9%), in contrast to hospitals without (+10%). The influence of CT on average length of stay appeared minimal. Although this study was limited, the authors believe that use of CT influenced changes in radiologic utilization.     

On the mechanism of the effects of potassium restriction on blood pressure and renal sodium retention

Dietary potassium restriction increases sodium and chloride retention, whereas potassium administration promotes both diuresis and natriuresis. In epidemiologic and clinical studies, potassium intake is inversely related to blood pressure and is lower in blacks than in whites. The present studies examined the mechanism by which potassium restriction fosters sodium conservation and the impact of race on this response. Twenty-one healthy black and white men and women ingested an isocaloric, potassium-restricted diet (20 mmol/d) containing 180 mmol/d of sodium with and without a potassium supplement (80 mmol/d) for 9 days on two occasions. Additionally, eight of these subjects ingested the same diets for 3 days followed by a water load to determine free water clearance before and during the early phase of dietary potassium restriction. During potassium restriction, mean arterial pressure (MAP) derived from 24-hour blood pressure measurements was higher (85.7 +/- 1.6 mm Hg v 82.0 +/- 1.3 mm Hg; P < 0.001), cumulative sodium excretion lower (984 +/- 59 mmol/d v 1,256 +/- 58 mmol/d; P < 0.001), and weight greater (71.1 +/- 2.1 kg v 69.3 +/- 2.2 kg; P < 0.001). Blacks displayed no greater increase in MAP, although they excreted less sodium overall and less potassium on the potassium-supplemented diet. After a water load, minimum urine osmolality (Uosm) was lower (53.0 +/- 3.0 mOsm/L v 65.6 +/- 3.5 mOsm/L; P = 0.01) and free water clearance greater (4.44 +/- 0.59 mL/min v3.72 +/- 0.58 mL/min; P = 0.009) during potassium restriction. In conclusion, in healthy, normotensive subjects, potassium restriction was associated with an increase in blood pressure and volume expansion effected by increased renal sodium and chloride retention. Potassium restriction was also associated with increased free water clearance and enhanced diluting capacity consistent with augmentation of Na+, K+:2Cl- cotransporter activity in the thick ascending limb of Henle. This mechanism may play an important role in the renal adaptation required for potassium conservation, but at the expense of sodium chloride retention and an elevation in blood pressure.     

Stroke in the young: relationship with iron deficiency anemia and thrombocytosis

The recognition and treatment of stroke in children is challenging as there are fundamental developmental differences in children compared to adults. A young boy presented with sudden weakness of right side of body followed by unconsciousness and convulsion that was not preceded by any history of fever or trauma. Neurological examination revealed upper motor neuron lesion in the right extremities. CT scan showed diffuse hypodense area in fronto-parietal regions. Complete blood count and iron profile evaluated iron deficiency anemia with thrombocytosis. Thrombosis resulting from thrombocytosis secondary to iron deficiency anemia was considered as etiological explanation of stroke in this young child.     

胰岛素受体介导主要信号传导途径与胰岛素抵抗的治疗进展

目的:了解胰岛素受体介导的主要的信号传导途径与胰岛素抵抗的关系,总结胰岛素抵抗的药物治疗方法。方法:主要选择被Medline收录的外文文献和在国内核心杂志上发表的有关文献,就其内容进行分析、分类、归纳及总结。结果:胰岛素受体、胰岛素受体底物、磷脂酰肌醇-3-激酶及葡萄糖转运蛋白4信号传递关键分子受损是导致胰岛素抵抗的主要原因。α糖苷酶抑制剂、双胍类、噻唑烷二酮类药物等纠正胰岛素信号传导通路中的障碍,增加靶组织对胰岛素敏感性的措施,都是胰岛素抵抗的治疗方法。结论:胰岛素信号转导途径的任何一个环节受损均可导致胰岛素抵抗。影响胰岛素受体介导的信号传导的新药开发将成为改善胰岛素抵抗的新趋向。     

Interleukin-3 in cooperation with transforming growth factor beta induces granulocyte macrophage colony stimulating factor independent differentiation of human CD34+ hematopoietic progenitor cells into dendritic cells with features of Langerhans cells

Recently, we have reported that M-CSF in cooperation with TGF-beta1 can induce Langerhans cell (LC) development from hematopoietic progenitor cells (HPCs) without GM-CSF. In the present study, we examined whether TGF-beta1 changes the differentiation of HPCs induced by IL-3 towards LC development. We cultured HPCs in a serum-free medium in the presence of IL-3 and a combination cytokines including Flt3L, SCF, and TNF-alpha with or without TGF-beta1. DCs induced by the IL-3 culture (IL-3 DCs) did not significantly differ from those induced by the GM-CSF culture (GM-CSF DCs). Namely, both expressed CDla, F-cadherin, and Langerin in the presence of TGF-beta1 and stimulated allogeneic T cells at a similar magnitude. In contrast to GM-CSF DCs, IL-3 DCs lacked the expression of Birbeck granules (BGs) in spite of their expression of Langerin. When we compared the expression of Langerin between these two DCs, however, it became clear that both Langerin protein and mRNA were significantly lower in IL-3 DCs than in GM-CSF DCs. These studies again demonstrated the ability of TGF-beta1 to polarize the differentiation of HPCs induced by IL-3 towards LC development, although IL-3 DCs were unable to form BGs partly because of their poor ability to induce Langerin.