The in vitro pharmacological profile of KR31080, a nonpeptide AT1 receptor antagonist

Summary— KR31080 (2-butyl-5-methyl-6-(1-oxopyridin-2-yl)-3-[[2'-(1H-tetrazol-5-yl) biphenyl-4-yl]methyl]-3H-imidazo[4,5-b] pyridine) is a potent inhibitor of angiotensin type 1 (AT₁) receptors in rabbit aorta and human recombinant AT₁ receptors. In the isolated rabbit thoracic aorta, KR31080 caused a nonparallel shift to the right of the concentration-response curves to angiotensin II (All) with decreased maximal response (pD'₂ = 10.1 ± 0.1), but had no effect on the contractile response induced by norepinephrine. KR31080 inhibited specific [¹²⁵I]AII binding to rabbit aortic membranes (AT, receptors) and [¹²⁵I][Sar¹, Ile⁸]AII binding to human recombinant AT₁ receptors in a concentration-dependent manner with IC₅₀ values of 0.84 ± 0.08 nM and 1.92 ± 0.15 nM, respectively, but did not inhibit specific [¹²⁵I)AII binding to bovine cerebellum membranes (ÀT₂ receptors). In the Scatchard analysis, KR31080 interacted with rabbit aortic AT₁ receptors in a competitive manner, similar to losartan. These results demonstrate that KR31080 is a potent and AT₁ selective angiotensin receptor antagonist which exerts a competitive antagonism in the [¹²⁵I]AII binding assay and insurmountable AT₁ receptor antagonism in the functional study.     

球囊成形术后氯沙坦对兔血管内膜增殖及巨噬细胞表达的影响

目的　通过观察AT1受体的特异性拮抗剂氯沙坦 (Losartan)对兔腹主动脉球囊成形术后内膜增殖和巨噬细胞表达的影响 ,探讨氯沙坦治疗血管再狭窄的机制。方法　采用内皮剥脱加高脂饮食 (含 1 5 %胆固醇 )喂养 8周制作兔腹主动脉粥样硬化膜型 ,然后对狭窄部位行球囊成形术。术后氯沙坦组给予氯沙坦 10mg·kg-1·day-1口服 ,对照组喂生理盐水。 4周后取腹主动脉行组织形态学观察 ,用免疫组织化学方法分析巨噬细胞。结果　对照组内膜厚度 /中膜厚度比值为 0 65± 0 17,氯沙坦组则减少为0 44± 0 11(P <0 0 1) ,对照组内膜面积 /中膜面积比值为 0 74± 0 16,氯沙坦组则减少为 0 5 4± 0 13(P <0 0 1)。氯沙坦组新生内膜中巨噬细胞数亦较对照组显著减少 (P <0 0 1)。结论　氯沙坦通过抑制AngⅡ的作用进而抑制巨噬细胞的浸润 ,抑制炎症反应 ,从而减轻再狭窄     

Clinical performance of non-contact tonometry by Reichert AT550® in glaucomatous patients

Measuring intraocular pressure (IOP) by non-contact tonometry (NCT) has been demonstrated to be a valid and reliable technique to be used in primary eye care; it is easier to use, it does not transmit infectious diseases, and it is not necessary to use anaesthetic or staining eye drops. Recently, a new NCT device has showed an excellent level of agreement with Goldmann tonometry, but there are no records of its performance in glaucomatous eyes. To rectify this, IOP was measured in twenty-two patients (44 eyes) receiving medical treatment to control elevated IOP, with AT550 and Goldmann tonometry. Mean values of IOP were 18.98 +/- 2.77 and 19.08 +/- 3.02 mmHg using Goldmann and AT550, respectively. Plots of differences against means displayed good agreement (mean difference +/- limits of agreement, -0.09 +/- 3.30); this value was not significantly different from zero (t-test for dependent samples, p = 0.709). In conclusion, IOP values as measured with the AT550 NCT are clinically comparable with those obtained with Goldmann tonometry in glaucomatous patients. This validates this NCT not only for screening of IOP but to follow-up glaucomatous patients with a rapid, non-invasive method.     

Safety of virus inactivated antithrombin III concentrate ANTITHROMBIN III IMMUNO (AT III)

In a prospective clinical trial the risk of infection after application of virus inactivated antithrombin III concentrate ANTITHROMBIN III IMMUNO (AT III) was investigated in patients undergoing cardiovascular surgery. The study was conducted according to the recommendations of the International Committee on Thrombosis and Hemostasis (ICTH), with the exception that most patients required additional blood products as well as AT III.

Twenty-seven patients were eligible to test for the risk of acquiring hepatitis B. Twenty-six patients could be evaluated in terms of hepatitis NANB transmission considering ALT-levels whereas 20 patients could be tested for anti-HCV one year after surgery. Samples from 78 patients could be monitored for anti-HIV-1. None of these patients showed any signs of infection. AT III IMMUNO seems to be an antithrombin III concentrate with low or absent infectivity.     

Anti-AT1R autoantibodies and prediction of the severity of Covid-19

The stimulation of AT1R (Angiotensin II Receptor Type 1) by Angiotensin II has, in addition to the effects on the renin-angiotensin system, also pro-inflammatory effects through stimulation of ADAM17 and subsequent production of INF-gamma and Interleukin-6. This pro-inflammatory action stimulate the cytokine storm that characterizes the most severe forms of SARS-CoV-2 infection. We studied the effect of AT1Rab on the AT1R on 74 subjects with SARS-CoV-2 infection with respiratory symptoms requiring hospitalization. We divided the patients into 2 groups: 34 with moderate and 40 with severe symptoms that required ICU admission. Hospitalized subjects showed a 50% reduction in the frequency of AT1Rab compared to healthy reference population. Of the ICU patients, 33/40 (82.5%) were AT1Rab negative and 16/33 of them (48.5%) died. All 7 patients positive for AT1Rab survived. These preliminary data seem to indicate a protective role played by AT1R autoantibodies on inflammatory activation in SARS-CoV-2 infection pathology.     

Frequent expression of the multi-drug resistance-associated protein BCRP/MXR/ABCP/ABCG2 in human tumours detected by the BXP-21 monoclonal antibody in paraffin-embedded material

The expression and cellular localization of angiotensin II (Ang II) and AT(1) receptor proteins were examined in the normal human prostate and benign prostatic hyperplasia (BPH) by immunohistochemistry. In the normal prostate, Ang II immunoreactivity was localized to the basal layer of the epithelium and AT(1) receptor immunostaining was found predominantly on stromal smooth muscle and also on vascular smooth muscle of prostatic blood vessels. Ang II immunoreactivity was markedly increased in hyperplastic acini in BPH compared with acini in the normal prostate (normal: 7.4+/-0.2%, n=5 vs. BPH: 22.7+/-1.9%, n=5, p<0.001). However, AT(1) receptor immunoreactivity was significantly decreased in BPH compared with the normal prostate [normal: 16.4+/-2.2%, n=4 vs. BPH: 9.4+/-1.3%, n=5, p<0.05 (p=0.025)]. The present study demonstrates the presence of Ang II peptide in the basal layer of the epithelium and AT(1) receptors on stromal smooth muscle, suggesting that Ang II may mediate paracrine functions on cellular growth and smooth muscle tone in the human prostate. Furthermore, AT(1) receptor down-regulation in BPH may be due to receptor hyperstimulation by increased local levels of Ang II in BPH. These data extend previous findings in support of the novel concept that overactivity of the renin-angiotensin system (RAS) may be involved in the pathophysiology of BPH.     

CATs and HATs: the SLC7 family of amino acid transporters

The SLC7 family is divided into two subgroups, the cationic amino acid transporters (the CAT family, SLC7A1–4) and the glycoprotein-associated amino acid transporters (the gpaAT family, SLC7A5–11), also called light chains or catalytic chains of the hetero(di)meric amino acid transporters (HAT). The associated glycoproteins (heavy chains) 4F2hc (CD98) or rBAT (D2, NBAT) form the SLC3 family. Members of the CAT family transport essentially cationic amino acids by facilitated diffusion with differential trans-stimulation by intracellular substrates. In some cells, they may regulate the rate of NO synthesis by controlling the uptake of l-arginine as the substrate for nitric oxide synthase (NOS). The heterodimeric amino acid transporters are, in contrast, quite diverse in terms of substrate selectivity and function (mostly) as obligatory exchangers. Their selectivity ranges from large neutral amino acids (system L) to small neutral amino acids (ala, ser, cys-preferring, system asc), negatively charged amino acid (system x_c^–) and cationic amino acids plus neutral amino acids (system y⁺L and b^0,+-like). Cotransport of Na⁺ is observed only for the y⁺L transporters when they carry neutral amino acids. Mutations in b^0,+-like and y⁺L transporters lead to the hereditary diseases cystinuria and lysinuric protein intolerance (LPI), respectively.     

Mutation detection in the alpha-1 antitrypsin gene (PI) using denaturing gradient gel electrophoresis

A method for mutation detection in the alpha-1 antitrypsin gene (protease inhibitor 1; PI) has been developed using denaturing gradient gel electrophoresis of PCR amplified gene fragments. Using this experimental approach, all common phenotypes and mutations could be detected. Denaturing gradient gel electrophoresis (DGGE) was compared with standard isoelectric focusing (IEF) in 20 potential alpha1-antitrypsin deficient patients and their relatives. The genotype determined by DGGE was found to be more reliable in some cases than IEF, which is essential for a proper diagnosis of alpha-1 antitrypsin malfunctioning.     

Behavioral Characterization of Alcohol-Tolerant and Alcohol-Nontolerant Rat Lines and an F2 Generation

The Alcohol Tolerant (AT) and Alcohol Nontolerant (ANT) rats, selectively bred for ethanol-induced ataxia on the inclined plane at ALKO in Finland, were moved to the University of Colorado in 1998. The selection phenotype was tested on generation 60 animals in Colorado. In week one, ataxia was measured on the inclined plane 30 minutes after an intraperitoneal dose of 2 g/kg 15% w/v ethanol. Differences in ethanol-induced ataxia between the AT and ANT lines at the University of Colorado were similar to those in the original lines in Finland. In week two, ataxia was measured on the inclined plane at 5 and 30 minutes, and tolerance was measured as the time to regain the original angle of sliding. The AT rats rapidly developed tolerance to 2 g/kg ethanol on the inclined plane; tolerance development was significantly slower in the ANT rats. In week three, the animals were tested for the duration of loss of righting reflex (LORR) and blood ethanol concentration at regain of the righting reflex (BEC_RRR) following a dose of 3.5 g/kg. The AT rats had a significantly higher BEC_RRR than did the ANT rats, but did not differ in LORR. A separate experiment with previously untreated rats demonstrated that naïve animals of the two lines did not differ in BEC_RRR or LORR. AT and ANT rats were genotyped for the mutation that occurs in the gene for the α6 subunit of the GABA_A receptor, a natural mutation that is known to affect benzodiazepine responses. All ANT animals tested carried the mutant allele, whereas some AT families carried the mutation and others were wild type. There was no effect of the mutation in AT rats for any of the phenotypes that were tested. After several generations of brother–sister mating, the AT and ANT lines were more than 90% inbred as determined by genotyping. One AT (wild-type) line and one ANT (mutant) line were selected for breeding an F₂ intercross generation of 1200 animals. They were phenotyped for sensitivity and tolerance to ethanol on each of three consecutive weeks. Order of testing had a modest effect on some of the phenotypes: when tested during the third week as compared to weeks one or two, BEC_RRR was increased, 30-minute sensitivity was increased, and development of acute tolerance was increased. Statistically significant correlations were found between tolerance and sensitivity at both 5 and 30 minutes, and between LORR and BEC_RRR. The smaller (or absence of) significant correlations between others of the phenotypes indicate(s) that they are most likely controlled by different sets of genes.