基于7次跨膜受体的药物发现基本方法——细胞检测

随着检测技术进步,含7个跨膜α螺旋结构的受体性质已渐为人们所了解。7次跨膜（7TM）受体不仅具有开关功能,更类似于信息微处理器;特定配体只能参与特定受体介导的部分信号机制,这就为药物发现开拓了一个新领域。为进一步发现7TM受体与配体间的新行为并量化评价药物对这一复杂系统的作用效能,进而指导药物化学研究,药理学检测已成为关注焦点。本文阐述从还原重组体到整体系统测定方法的回归,讨论药物效价与评价其效应的特定检测方法间的联系,强调新的检测方法在药物发现过程中的价值。     

Human thyroid tumor cell lines derived from different tumor types present a common dedifferentiated phenotype

Cell lines are crucial to elucidate mechanisms of tumorigenesis and serve as tools for cancer treatment screenings. Therefore, careful validation of whether these models have conserved properties of in vivo tumors is highly important. Thyrocyte-derived tumors are very interesting for cancer biology studies because from one cell type, at least five histologically characterized different benign and malignant tumor types can arise. To investigate whether thyroid tumor-derived cell lines are representative in vitro models, characteristics of eight of those cell lines were investigated with microarrays, differentiation markers, and karyotyping. Our results indicate that these cell lines derived from differentiated and undifferentiated tumor types have evolved in vitro into similar phenotypes with gene expression profiles the closest to in vivo undifferentiated tumors. Accordingly, the absence of expression of most thyrocyte-specific genes, the nonresponsiveness to thyrotropin, as well as their large number of chromosomal abnormalities, suggest that these cell lines have acquired characteristics of fully dedifferentiated cells. They represent the outcome of an adaptation and evolution in vitro, which questions the reliability of these cell lines as models for differentiated tumors. However, they may represent useful models for undifferentiated cancers, and by their comparison with differentiated cells, can help to define the genes involved in the differentiation/dedifferentiation process. The use of any cell line as a model for a cancer therefore requires prior careful and thorough validation for the investigated property.     

Sequestrum-like appearance of a multiple sclerosis brain lesion on serial magnetic resonance images.

Using serial magnetic resonance imaging, we monitored an unique lesion of the brain in a 15-year-old girl with clinically definite and laboratory-supported remitting-relapsing multiple sclerosis. During initial phases of the disease course, cystic necrosis around the plaque was observed. Later, remyelination of the central core of the lesion was speculated, as similarities in signal intensity between the core and the normal appearing white matter were partially recovered both on the T1- and the T2-weighted images.     

Inverse relation between aldosterone and venous capacitance in chronically treated congestive heart failure

The purpose of this study was to examine if there is a relation between the aldosterone escape phenomenon and venous capacitance of the upper and lower limbs in patients with long-term congestive heart failure (CHF) receiving chronic treatment with angiotensin-converting enzyme (ACE) inhibitors. The study group consisted of 16 subjects with ischemic CHF in New York Heart Association functional class II (age 59 +/-2 years, ejection fraction 24+/-4%), stabilized under a constant drug regimen comprising furosemide, captopril 50 mg 3 times daily, and digoxin for at least 3 months. Thirteen apparently healthy volunteers, aged 50+/-4 years acted as controls. Forearm and calf venous capacitances were measured simultaneously by venous occlusion plethysmography using mercury-in-silastic strain gauges. The equilibration technique was used to derive venous capacitance from the recorded pressure-volume curves. Active renin, angiotensin II, and aldosterone levels were determined on venous blood samples obtained in the supine position. Angiotensin II (p<0.05) and aldosterone (p<0.01) were statistically significantly higher in patients with CHF under long-term ACE inhibition than in controls (aldosterone escape phenomenon). In CHF, forearm venous capacitance was 2.19+/-0.18 ml/100 ml; calf venous capacitance was 2.83+/-0.27 ml/100 ml. Aldosterone significantly and inversely correlated with venous capacitance in both upper (r = -0.586; p = 0.017) and lower (r = -0.625; p = 0.01) limbs. No correlations were found between forearm or calf venous capacitance and renin or angiotensin II. In patients with heart failure chronically treated with diuretics and full ACE inhibition, venous capacitance is inversely correlated with aldosterone through the mechanism of aldosterone escape, creating the potential for further deterioration of the CHF process.     

The potential role of angiotensin-converting enzyme inhibition in peripheral arterial disease

Peripheral arterial disease (PAD) is associated with significant morbidity and mortality, and yet remains under-recognized and under-treated. Atherosclerosis is the most common cause of lower extremity PAD and pharmacological interventions that alter this central pathogenic role of atherosclerosis may alter the natural history of PAD. There is growing evidence that the renin-angiotensin system (RAS) is a significant mediator of this disease process and that treatment with angiotensin-converting enzyme (ACE) inhibitors is associated with vasculoprotective effects that are independent of the antihypertensive properties of these agents. Numerous lines of evidence suggest that ACE inhibitors directly inhibit the atherosclerotic process and improve vascular endothelial function. In patients with PAD, ACE inhibitors have been shown to improve peripheral circulation as measured by peripheral arterial blood pressure and by increases in peripheral blood flow. Preliminary evidence suggests that ACE inhibitors might improve clinical symptoms in patients with PAD. Recent evidence has confirmed that ACE inhibition is associated with a decrease in morbidity and mortality in patients with arterial disease without left ventricular dysfunction; this benefit was at least as great for the subset of patients with PAD. Overall, these data support a significant role for the RAS in the pathogenesis of all atherosclerotic diseases (including PAD) and suggest that the benefit is independent of the blood pressure lowering properties of these agents. These studies suggest that ACE inhibitor therapy should be considered in the routine management of individuals with PAD, regardless of whether they have hypertension or left ventricular dysfunction.     

Clinical applications of arterial stiffness; definitions and reference values

Arterial stiffening is the most important cause of increasing systolic and pulse pressure, and for decreasing diastolic pressure beyond 40 years of age. Stiffening affects predominantly the aorta and proximal elastic arteries, and to a lesser degree the peripheral muscular arteries. While conceptually a Windkessel model is the simplest way to visualize the cushioning function of arteries, this is not useful clinically under changing conditions when effects of wave reflection become prominent. Many measures have been applied to quantify stiffness, but all are approximations only, on account of the nonhomogeneous structure of the arterial wall, its variability in different locations, at different levels of distending pressure, and with changes in smooth muscle tone. This article summarizes the methods and indices used to estimate arterial stiffness, and provides values from a survey of the literature, followed by recommendations of an international group of workers in the field who attended the First Consensus Conference on Arterial Stiffness, which was held in Paris during 2000, under the chairmanship of M.E. Safar and E.D. Frohlich.     

Prevalence of hypertension in the adult population of Belgium: report of a worksite study, Attention Hypertension

Hypertension remains a major cause of cardiovascular morbidity in Belgium. Information on the prevalence of hypertension in the working population is desirable. A worksite study of hypertension prevalence was carried out in Belgium where 3472 individuals were screened for 1 week. The result was that high blood pressure (> or = 140/90 mm Hg) was identified in approximately one-third of the men and one-quarter of the women even though the majority of subjects had no recorded history of hypertension. Associations were identified between age and systolic blood pressure and, in men, between systolic blood pressure and alcohol consumption. Most participants in the survey were unaware of their serum cholesterol level. The results of this survey suggest that a large proportion of subjects with high blood pressure in the Belgian working population remain unidentified and indicate a lack of awareness about other cardiovascular risk factors.     

Systolic hypertension in the elderly: addressing an unmet need

Systolic hypertension is a major public health issue in the elderly and is often under-recognized and under-treated. The concept that systolic blood pressure increases with age should be considered a pathophysiologic concept. Aging of the cardiovascular system is accompanied by endothelial dysfunction, activation of the renin-angiotensin system and, consequently, vascular remodeling. This process leads to an increase in large artery stiffness and an increase in arterial wave reflections to the heart. These processes in daily clinical practice translate to an increase in systolic blood pressure, which is associated with increased cardiovascular morbidity and mortality. Evidence-based medicine recommendations to treat systolic hypertension in the elderly are based on landmark and recent clinical trials, which clearly demonstrated that treatment of isolated systolic hypertension is associated with significant decreases in cardiovascular morbidity and mortality. However, treatment of systolic hypertension in older adults remains disappointing because therapeutic goals often are not reached. Therefore, emphasis should be placed on the treatment of systolic hypertension in the elderly, and there is need for more effective, individualized antihypertensive therapy.     

Induction of NK activity in large granular lymphocyte leukemia: activation with anti-CD3 monoclonal antibody and interleukin 2

Large granular lymphocyte (LGL) leukemia is a rare disease characterized by clonal expansion of LGL associated with chronic neutropenia, multiple auto-antibodies, and occasionally polyarthritis. We studied cell surface antigen expression and functional activity of leukemic LGL from ten such patients. Using two-color flow cytometric analysis, we found that leukemic LGL from all ten patients expressed the CD3 and HNK-1 markers, while cells from only four patients expressed IgG Fc receptors (FcR). The LGL leukemic cells had little or no NK activity (defined as MHC-nonrestricted cytotoxicity against K562 target cells); however, NK activity could be induced in leukemic LGL by in vitro treatment with as little as 0.05 microgram/mL of anti-CD3 monoclonal antibody. Cell sorting experiments demonstrated that NK activity was induced in CD3+ leukemic LGL (either CD3+, HNK-1+ or CD3+, FcR+) with anti-CD3 monoclonal antibody but not in normal CD3+, FcR- T cells. Treatment with purified interleukin 2 (IL 2) also caused direct activation of some CD3+ leukemic LGL. Despite induction with anti-CD3 MAb or IL 2, activated leukemic LGL did not proliferate or express high density IL 2 receptors detectable by cell sorter analysis. Treatment with alpha interferon had minimal effect on NK activity of LGL leukemic cells. These results suggest that leukemic LGL may provide a useful model for examining the signals required for LGL maturation and activation.