The binding of ouabain to normal and chronic lymphocytic leukemic lymphocytes

The binding of the cardiac glycoside, ouabain, to cells had been used to quantify the number of active cation pumps. In this study, lymphocytes were incubated with 3H-ouabain and the equilibrium binding analyzed for the maximal number of specific binding sites. Lymphocytes from normal peripheral blood bound 44,200 +/- 9920 molecules/cell, compared with 29,200 +/- 8370 molecules/cell for the lymphocytes of chronic lymphocytic leukemia (CLL) subjects. This difference was significant (p less than 0.01) and did not reflect a lower number of sites on B cells than T cells, since B-cell-enriched lymphocytes from normal peripheral blood showed the same ouabain binding characteristics as the standard T-cell-rich preparation. Although monocytes bind threefold more ouabain than lymphocytes, the small monocyte contamination (3.0%) in normal lymphocyte preparations could not account for the difference between normal and CLL. The fewer ouabain binding sites on CLL lymphocytes may reflect both their smaller size (by 10%) and lower mitotic activity compared with lymphocytes from normal peripheral blood.     

Inhibition of thromboxane formation in vivo and ex vivo: implications for therapy with platelet inhibitory drugs

The capacity of platelets to generate thromboxane A2, reflected by measurement of serum thromboxane B2 (TxB2), greatly exceeds the systemic production of thromboxane in vivo. Thus, it is possible that substantial but incomplete inhibition of thromboxane formation ex vivo would still allow marked augmentation of thromboxane production in vivo. To address this hypothesis, we administered aspirin 120 mg, a selective inhibitor of thromboxane synthase (TxSl), 3-(1H-imidazol-1-yl- methyl)-2-methyl-1H-indole-1-propanoic acid (UK-38, 485) 200 mg, and a combination of both drugs to 12 healthy volunteers and measured the effects on serum TxB2 and urinary 2,3-dinor-thromboxane B2 (Tx-M), an index of endogenous thromboxane biosynthesis. Although serum TxB2 was maximally inhibited by 94 +/- 1% after aspirin and 96 +/- 2% after the TxSl, maximal depression of Tx-M was only 28 +/- 8% and 37 +/- 9%, respectively. Combination of aspirin with the TxSl resulted in a small but significant increase in inhibition of thromboxane generation ex vivo (98 +/- 1% v 94 +/- 1%; P less than 0.05), but a disproportionately greater fall in thromboxane synthesis in vivo (58 +/- 7%; P less than 0.01). Consistent with further inhibition of platelet thromboxane synthesis, addition of the TxSl abolished the transient decline in prostacyclin formation after aspirin alone. Administration of a lower dose of aspirin (20 mg) to 6 healthy subjects caused a small reduction in Tx-M (12 +/- 4%; P less than 0.05) and inhibited serum TxB2 by 48 +/- 2%. The relationship between inhibition of platelet capacity to form thromboxane ex vivo (serum TxB2) and synthesis in vivo (Tx-M) departed markedly from the line of identity. When total blockade of the capacity of platelets to generate thromboxane is approached, minor decrements in capacity result in a disproportionate depression of actual thromboxane biosynthesis. These results imply that pharmacologic inhibition of serum TxB2 must be virtually complete before thromboxane- dependent platelet activation is influenced in vivo.     

CN80-2对鼠肝匀浆SOD,GSH-PX 的影响

本文给小鼠 CN80-2灌胃(3g/kg)14天,及鼠肝组织中加入 CN80-2(0.3g/ml)温育2h,均可提高鼠肝组织中超氧化物歧化酶含量(P<0.01,P<0.05),其抑制脂质过氧化物的作用与冬虫夏草相近(P<0.05),CN80-2还可提高谷胱甘肽过氧化物酶的含量。     

Nitric oxide and the control of renin secretion

Summary— Research during recent years has established nitric oxide as a unique signaling molecule that plays important roles in the regulation of the cardiovascular, nervous, renal, immune and other systems. Nitric oxide has also been implicated in the control of the secretion of hormones by the pancreas, hypothalamus, pituitary and other endocrine glands, and evidence is accumulating that it contributes to the regulation of the secretion of renin by the kidneys. The enzyme nitric oxide synthetase is present in vascular and tubular elements of the kidney, particularly in cells of the macula densa , a structure that plays an important role in the control of renin secretion. Guanylyl cyclase, a major target for nitric oxide, is also present in the kidney and is responsive to changes in nitric oxide levels. Drugs that inhibit nitric oxide synthesis generally suppress renin release in vivo and in vitro , suggesting a stimulatory role for the L-arginine-nitric oxide pathway in the control of renin secretion. Under some conditions, however, blockade of nitric oxide synthesis increases renin secretion. Recent studies indicate that nitric oxide not only contributes to the regulation of basal renin secretion, but also participates in the renin secretory responses to activation of the renal baroreceptor, macula densa and beta adrenoceptor mechanisms that regulate renin secretion. Future research should clarify the mechanisms by which nitric oxide regulates the secretion of renin and establish the physiological significance of this regulation.     

Virus directed enzyme prodrug therapy for ovarian and pancreatic cancer using retrovirally delivered E. coli nitroreductase and CB1954.

Expression of the E. coli enzyme nitroreductase (NTR) in tumour cells enables them to activate the prodrug CB1954 (5-(aziridin-1-yl)-2,4-dinitrobenzamide), leading to interstrand DNA crosslinking and cell death. Using transfected or retrovirally transduced SKOV3 ovarian carcinoma cell clones, we show a strong correlation between sensitivity to CB1954 and level of NTR enzyme activity. Importantly for clinical application in ovarian cancer, a cisplatin-resistant ovarian tumour cell line remains as susceptible to the NTR-dependent cytotoxicity of CB1954 as parental cells. In mixed populations of NTR-expressing and non-expressing cells, we observe a marked 'bystander killing' effect with this system. The use of NTR-encoding retroviruses from clonal producer cell lines at titres of 5 x 10(5) c.f.u./ml to transduce either established or low passage primary ovarian carcinoma lines only achieves an average 10-fold sensitisation of the cultures at gene transfer efficiencies of 15-25%. Concentration of the retrovirus to 3 x 10(7) c.f.u./ml elevates gene transfer to 80-90% in a single exposure to target cells, resulting in up to 500-fold sensitisation of the entire, unselected SKOV3 population to CB1954. In an initial investigation of NTR/CB1954 for the treatment of tumours in vivo, we observe regression of tumours expressing NTR following administration of CB1954, resulting in significantly increased median survival.