Endothelial progenitor cell senescence is accelerated in both experimental hypertensive rats and patients with essential hypertension

OBJECTIVES

Recent studies have revealed an association between coronary risk factors and both the number and function of bone marrow-derived endothelial progenitor cells (EPCs). Although hypertension is an important coronary risk factor, the influence to the EPCs is not fully understood. We investigated the effect of hypertension on EPC senescence.

METHODS

Experimental study We investigated the number and senescence of EPCs in spontaneously hypertensive rats (SHR/Izm) and deoxycorticosterone acetate (DOCA)-salt hypertensive rats. EPCs were isolated from peripheral blood of rats and were characterized. EPC senescence was detected by acidic beta-galactosidase staining. In addition, we measured the telomerase activity using polymerase chain reaction-enzyme-linked immunosorbent assay.

CLINICAL STUDY

EPCs were isolated from peripheral blood samples in 37 patients with essential hypertension. After ex-vivo cultivation, we detected senescence and measured the telomerase activity. The total severity index of hypertension-induced organ damage was calculated by the summation of each severity index in the classification of hypertension severity by Tokyo University (1984).

RESULTS

Experimental study The EPC senescence in SHR/Izm and DOCA-salt hypertensive rats was significantly increased compared with that of control rats. The telomerase activities in SHR/Izm and DOCA-salt hypertensive sensitive rats were also significantly lowered compared with those of control rats. Clinical study Compared with the control group, EPCs from hypertensive patients showed accelerated senescence and also showed reduced telomerase activity. In hypertensive patients, the degree of hypertension-induced organ damage was negatively correlated with telomerase activity, and was positively correlated with EPC senescence.

CONCLUSIONS

EPC senescence is accelerated in both experimental hypertensive rats and patients with essential hypertension, which may be related to telomerase inactivation. The hypertension-induced EPC senescence may affect the process of vascular remodeling.

Leukemia inhibitory factor relaxes arteries through endothelium-dependent mechanism

Leukemia inhibitory factor (LIF) is a cytokine, which inhibits angiogenesis and decreases endothelial cell proliferation and migration, suggesting that LIF may modulate vascular tone. In this study, we examined the effects of LIF on the tone of rat arteries. The isometric tension of ring preparations from rat superior mesenteric arteries was continuously measured. LIF relaxed the mesenteric arteries in a dose-dependent manner, when the arterial rings were precontracted with phenylephrine. The relaxation was totally inhibited by mechanical removal of endothelium. N(G)-nitro-L-arginine methyl ester did not affect the relaxation by LIF. Ca(2+)-dependent K channel (KCa) blockers, apamin with charybdotoxin, inhibited the relaxation by LIF. Catalase, an enzyme which scavenges hydrogen peroxide, also inhibited the relaxation by LIF. Endothelium-derived hyperpolarizing factor relaxes smooth muscle cells and the effect is blocked by KCa and catalase. Our results suggest that LIF regulates vascular tone through the effect of this factor.

Usefulness of saturation pulses in magnetic resonance imaging of partial anomalous pulmonary venous return

The authors evaluated partial anomalous pulmonary venous return by magnetic resonance (MR) images. Seven patients with this congenital anomaly underwent MR imaging examination. Conventional spin-echo and gradient-echo imaging were performed. In addition, during acquisition of gradient-echo images, saturation pulses were imposed on the affected lung. Spin-echo images showed the anatomical situation of the anomalous veins, and gradient-echo images revealed the blood flow in the veins. With saturation technique, the direction and drainage of blood flow in the anomalous veins were well defined. The study suggests that MR imaging with spin-echo method and gradient-echo method with or without saturation pulses is a useful and noninvasive method of diagnosing partial anomalous pulmonary venous return. MR images with spin- and gradient-echo methods were useful in defining the anatomical situation and blood flow in the anomalous veins. By imposing saturation pulses on the affected lung field, the direction and drainage of blood flow in the anomalous veins were clearly demonstrated.

Involvement of nitric oxide in endothelium-dependent arterial relaxation by leptin

Leptin is a polypeptide, mainly produced in white adipose tissue, and increases sympathetic nerve activity. A few studies investigated leptin's effect on peripheral vessels. We examined the vasorelaxant effects of human leptin on rat arteries. Arterial rings were precontracted with 1 x 10(-6) mol/l of phenylephrine, and leptin was superfused. Leptin relaxed phenylephrine-precontracted arterial rings in a dose-dependent manner. ED50 was calculated to 8.4 microg/ml. Removal of endothelium abolished the effects of leptin. Indomethacin (1 x 10(-5) mol/l) did not affect the vasorelaxation by leptin, whereas 1 x 10(-4) mol/l of N(omega)-nitro-L-arginine methyl ester (L-NAME) completely suppressed it. The inhibition was antagonized by 1 x 10(-4) mol/l of L-arginine. Leptin normally relaxed arterial rings during superfusion of K channel blockers, including 3 x 10(-5) mol/l of glibenclamide, 1 x 10(-6) of mol/l apamin, and 5 x 10(-7) mol/l of charybdotoxin. Low Cl(-) solution (8. 3 mmol/l) inhibited leptin-induced relaxation, but endothelium-independent vasodilatation by nitroprusside was not impaired at low Cl(-) solution. These results suggest that arterial relaxation by leptin is mediated by nitric oxide released from endothelium, and Cl(-) plays an important role in leptin-induced nitric oxide release.

Food intake and food consumption patterns of hospital workers in the dominican republic

Coronary heart disease (CHD) is the leading cause of death according to official mortality statistics in the Dominican Republic. The purpose of this study was to assess food intake and food consumption patterns of Dominicans and to discuss CHD risks related to nutrient intake. The subjects were 22 men and 81 women voluntarily recruited among 230 hospital workers in Santo Domingo. The mean nutrient intake and food consumption were estimated from a single 24-hour recall method administered by trained persons who elicited each subject's previous day's intake from midnight to midnight. The mean energy intake was 2030 kcal. The mean intake of total protein, total fat and carbohydrates were 66.3g, 89.1 g and 248g, respectively. Percentage of energy from total fat was 39.5%, which was higher than WHO recommendations. But, the percentage of animal fat per total fat was 46.8%. Especially, the value in the low income group was 31.7%. Moreover, we analyzed the food consumption structure in order to understand the Dominican dietary pattern, and three factors were found to explain the characteristics on the basis of factor analysis.The low percentage of animal fat was due to the diets rich in vegetable oil. Our results suggested that it was difficult to assume that CHD risks increased as a result of the Dominican dietary pattern. This was consistent with our previous findings that the average serum cholesterol level of Dominicans was generally low.

Ultrastructural immunolocalization of kallikrein in apical granules of striated duct cells of cat submandibular gland

Recent studies on the localization of the serine protease salivary kallikrein have led to the conclusion that it has a ductal localization and to the possibility that it is located there in small "secretory" granules. Until now, the latter inference has been based entirely on circumstantial evidence. In the present study, however, direct evidence from immunolocalization studies at the ultrastructural level establishes the localization of this enzyme in the apical duct granules in the cat submandibular gland. These granules stained only with immune sera to cat submandibular gland kallikrein and were the only subcellular structures that did so. They showed the "studded" appearance characteristic of the electron-dense aggregates of peroxidase-antiperoxidase seen in this type of immune reaction.

Studies on the effects of sugars on washed human sperm motility

The motility of ejaculated human sperm which was washed thoroughly by Ficoll gradient centrifugation to remove seminal plasma was investigated in the presence of various concentrations of sugars. Washed human sperm showed high motility in an artificial medium containing glucose and fructose, which were major sugar components of semen. However, mannitol and 3-O-methyl-D-glucose had no effect on sperm motility. Dose-response curves of sperm motility in the additions of glucose or fructose were bell-shaped. The maximum sperm motility was found in the medium with 1 mM glucose or 15 mM fructose. When, however, both 1 mM glucose and 15 mM fructose were added to the medium, sperm motility was higher than that with an individual sugar. Although phlorizin decreased glucose activated sperm motility, it has no effect in case fructose was the activator. The results suggest that the effect of glucose on human sperm motility is due to a different mechanism from that of fructose.

Effects of kinins and dipeptidyl carboxypeptidase on the motility of highly washed human sperm

The influences of bradykinin, kallidin and dipeptidyl carboxypeptidase (kininase II) on the motility of human sperm thoroughly washed with Ficoll were investigated by an objective method with multiple exposure photography technique which recorded stroboscopically the tract of sperm migration. Addition of 0.1--10 ng/ml of bradykinin or kallidin to sperm suspension caused a stimulation of motility. The effect appeared by increase of the velocity of forward motile sperm, whereas the percent of motile sperm was not altered. On the contrary, higher dose of kinins suppressed the motility by decreasing the percent of motile sperm. There was a minor contamination of dipeptidyl carboxypeptidase even in the highly washed sperm suspension. This enzyme was identical with angiotensin I converting enzyme or kininase II and the major enzyme of kinin degrading activity in seminal plasma. Stimulation of sperm motility by kinin was further enhanced in the presence of SQ 14225, a specific inhibitor of dipeptidyl carboxypeptidase, by protection of added kinins from the residual dipeptidyl carboxypeptidase in the sperm suspension. Dipeptidyl carboxypeptidase level in ejaculated human semen was found to correlate to the semen quality, such as sperm density and motility, but it gave no direct influence on sperm motility.

Studies on dipeptidyl carboxypeptidase in the male reproductive organs; its biological and pathological status

There are potent kinin degrading activities in seminal plasma and testis of various mammals. The activities in boar and human seminal plasma, and testis extracts from boar, rat, guinea pig and rabbit were eluted out at a similar position as a single peak in column chromatography with Sephadex G-200 or DEAE Sephadex A-50. These enzymes degraded synthetic bradykinin and yielded angiotensin II from angiotensin I by cleaving the second peptide bond from the carboxytermini of the substrate, and it was concluded that these enzymes were dipeptidyl carboxypeptidases like kininase II or angiotensin I converting enzyme. The enzymes in male genital organs of these mammals were found to be identical with further investigation on the enzymic properties of them. The enzyme in rat testis increased significantly in accordance with sexual maturation, and the increase was suppressed by injection of danazol or diethylstilbesterol to rats. Furthermore, the dipeptidyl carboxypeptidase content in human seminal plasma was positively correlated to the semen qualities, i.e. sperm density and motility. From these results it is supposed that dipeptidyl carboxypeptidase in male genital organ and its secretion seem to be related to the male reproductive functions.

Studies on acrosin. I. Purification and characterization of boar acrosin

Acrosin was extracted from boar sperm and purified by Sephadex gel filtration and affinity chromatography on Phe-Phe-Arg Sepharose 4B in acidic condition. Its enzymic properties were characterized in comparison with trypsin. The oligopeptides with Arg at the carboxy-termini were used as the ligands for affinity chromatography. Phe-Phe-Arg adsorbed acrosin at pH 5 and released in at pH 3. To adsorb acrosin, it was found that the ligand should be longer than tripeptide with Arg in the carboxy-termini. Disc gel electrophoretogram of purified boar acrosin gave a broad band consisted from three fractions which hydrolysed N-alpha-benzoyl-arginine ethylester (BAEE). The pH optimum and inhibition spectra were similar to those of trypsin, however, the influence of urea on them were very different among each other. Calcium ion decreased Km for BAEE, and increased Ki of aprotinin. The kinetic analysis of acrosin for its substrate and products resulted that Km for BAEE was minimal at around pH 8 and maximal at pH 5, on the contrary, Ki of the product was low at pH 5, but progressively increased along the elevation of pH. The same tendency was observed for trypsin. From the attitudes on the affinity chromatographies and the pH profiles of kinetics parameters, it was concluded that the active sites of acrosin and trypsin were similar to each other.

Localization of kallikrein in submandibular gland of cat, guinea pig, dog, and man by the immunoperoxidase method

The sensitive immunoperoxidase method was used to localize kallikrein in the submandibular gland of the cat, guinea pig, dog, and man. In every instance, kallikrein was localized in the apical region of duct cells, a location suggesting its secretion into the duct system. There was no evidence of the enzyme in other cells or interstitial tissue in the gland. The major source of submandibular gland kallikrein, therefore, must be of ductal origin. The classification of kallikreins with the widely distributed group of serine proteases is discussed, as is their possible significance in regulating physiological processes by specific and limited proteolysis.

Metalloenzyme inhibitor from kidney beans: partial purification and characterization

Inhibitory activity directed against metalloenzymes has been highly purified from extracts of red kidney beans (Phaseolus vulgaris). The inhibitor is a substance of small molecular weight and appears to be a chelator of Zn(2+). One milligram of the preparation inhibited 23 milligrams carboxypeptidase A. The inhibitor also strongly inhibited carboxypeptidase B and alkaline phosphatase and could activate phosphoglucomutase that had previously been inactivated with Zn(2+). The isoelectric point of the inhibitor is 4.7. The inhibitor activity was abolished by preincubation with Zn(2+), Ni(2+), Co(2+), or Cu(2+). The mechanism of inhibition of carboxypeptidases and alkaline phosphatase by the bean inhibitor is apparently due to the complexing and complete removal of Zn(2+) from the enzymes.

Purification of cat submaxillary kallikrein

The cat submaxillary gland contains 1,000--2,400 kallikrein units (KU)/g of tissue. The submaxillary kallikrein was purified to homogeneity by acetone fractionation, DEAE-Sephadex A-50 chromatography, Sephadex G-75 gel filtration, and Ampholine isoelectric focusing. The kallikrein was separated by isoelectric focusing into 6--7 forms with pI's between 4.2 and 5.1. One mg of the purified kallikrein contained 930--1,260 KU in the dog vasodilator assay, and hydrolyzed 15--25 and 9--12 mumol of N-alpha-benzoyl-L-arginine ethyl ester (BAEE) and N-alpha-toluenesulfonyl-L-arginine methyl ester (TAME), respectively, in 1 min at 25 degrees C and pH 8.0. The Km's of the purified kallikrein with BAEE and TAME were 0.67 and 0.34 mM, respectively. Hydrolysis of N-alpha-benzoyl-L-tyrosine ethyl ester (BTEE), N-alpha-benzoylarginine-p-nitroanilide (BApNA), and casein was small or negligible. The apparent molecular weight of the kallikrein was estimated to be 5 X 10(4) by Sephadex G-100 gel filtration and 4.7 X 10(4) by polyacrylamide gel electrophoresis with sodium dodecyl sulfate (SDS). The kallikrein was found to contain 18.5% carbohydrate by weight. Trasylol and soybean trypsin inhibitor were not specific inhibitors of this kallikrein.

Effect of kallikrein-kinin system on ion transport across rat small intestine

The flow of glucose and valine from the mucosal to the serosal side of rat intestine was stimulated significantly by kallikrein-kinin system. To elucidate the mechanism of this function the effects of kallidin on the transmural potential difference (PDt) between the serodal and the mucosal sides and the transepithelial resistance (Rt) of rat jejunum segment were investigated by electrophysiological procedures. The glucose-evoked PDt was not significantly altered by addition of kallidin to the mucosal fluid. Meanwhile, PDt which evoked by glucose was significantly shifted under the presence of 10-1-10(2) ng kallidin in the serosal fluid. The valine-evoked PDt was also changed by addition of 10 ng kallidin into the serosal fluid. However, the addition of glucose to the mucosal and kallidin to the serosal fluid did not affect on the Rt of the jejunum segment. These results suggest that kinin stimulated Na+ transport at the baso-lateral membrane of the intestinal absorptive cells, and the transports of other substances were enhanced consequently.

Localization of kallikrein in the coagulating and submandibular glands of the guinea pig

Antibody to pure kallikrein from the coagulating gland of the guinea pig was used to localize kallikrein in the gland by immunofluorescence techniques. This antibody also reacted with the guinea pig's submandibular gland kallikrein. The specific fluorescence in the coagulating gland was present diffusely in all secretory cells lining the crypts. In contrast to its diffuse location in the coagulating gland, kallikrein in the submandibular gland was specifically located in the luminal border of striated and some larger duct cells, whereas the acinar cells and interstitial tissue showed no significant fluorescence.

Direct evidence for the location of kallikrein in the striated ducts of the cat's submandibular gland by the use of specific antibody

Kallikrein was located in the apical portion of the striated duct cells of the cat's submandibular gland by an immunohistochemical technique. This portion only of these cells showed an intense band of specific fluorescence. There was no evidence of specific fluorescence in the acinar and demilune cells nor in the interstitial tissue or blood besells. In some sections the collecting ducts showed a very fine fluorescent luminal rim.

Dog renal kallikrein: purification and some properties

The contents of kallikrein [EC 3.4.21.8] in the kidneys of various animals were estimated and the activity was found to be most potent in dogs. The dog renal kallikrein (DRK) was located mainly in the kidney cortex. Following the activation of a dog kidney cortex homogenate with acetone, kallikrein was purified about 2,000-fold with an overall yield of 18% by diethylaminoethyl (DEAE)-cellulose adsorption, acetone fractionation, and chromatography on Sephadex G-75 and DEAE-Sephadex A-50. The final purified preparation of dog renal kallikrein had a vasodilator activity of 65.5 KU per A280, and appeared to be homogeneous both in disc electrophoresis and ultracentrifugal analysis. Its molecular weight was estimated to be approximately 3.8 X 10(4) from the sedimentation coefficient obtained by ultracentrifugation, and by Sephadex gel filtration. However, isoelectric fractionation of the purified DRK preparation gave three isoelectric point, 3.9, 4.1, and 4.3. The DRK had an optimum pH of about 8.6 and was stable at pH 8. This enzyme was hardly inhibited by Trasylol, soybean trypsin inhibitor, ovomucoid trypsin inhibitor or potato kallikrein inhibitors. These properties were compared with those of kallikrein from other sources; DRK appeared to be similar to urinary kallikrein.

Sialotonin: vasopressor substance in saliva and submandibular gland of the cat

1. The large molecular pressor agent, sialotonin, present in cat saliva, has been separated from kallikrein and characterized further. 2. Sialotonin is present in saliva produced by parasympathetic (ch8da) but not in that produced by sympathetic nerve stimulation. After degenerative preganglionic parasympathetic nerve section, both sialotonin and kallikrein disappear completely, or nearly so. Sympathetic nerve section, however, fails to affect the concentration of these substances in chorda saliva. 3. The sialotonin activity is saliva is unaffected by ligation of Wharton's duct for 3--4 days whereas the kallikrein concentration is greatly reduced. 4. Although normally present in chorda saliva, sialotonin cannot be detected in aqueous extracts of the submandibular gland. It is present, however, in extracts of glands which have previously been subjected to prolonged sympathetic nerve stimulation or to ligation of the duct for 3-4 days. 5. The intravenous or close-aterial injection of sialotonin causes marked but brief reductions of blood flow in the submaxillary gland and intestine.

Studies on urinary kallikreins. I. Purification and characterization of human urinary kallikreins

Human urinary kallikrein [EC 3.4.21.8] (HUK) was purified about 200-fold with an overall yield of 40 percent from crude powder by DEAE-cellulose chromatography, acetone fractionation, Sephadex G-100 gel filtration and DEAE-Sephadex A-50 chromatography. Its activity was 200 kallikrein units (KU) per A280. HUK from active fractions obtained by DEAE-Sephadex A-50 chromatography was separated into three active components showing isoelectric points of 3.9 (HUK-1), 4.0 (HUK-2), and 4.2 (HUK-3) by isoelectric focusing: each HUK component was homogeneous on disc electrophoresis. The approximate molecular weights of HUK-1, -2 and -3 were estimated to be 2.7 X 10(4), 2.7 X 10(4), and 2.9 X 10(4), respectively, by gel filtration on a Sephadex G-100 column. The optimum pH's of HUK-1, -2, and -3 in esterolytic action were found to be 8.0, 8.3, and 7.5, respectively, and they were fairly heat stable in comparison with other glandular kallikreins. The three components of HUK were weakly inhibited by Trasylol, but were not affected by soybean and ovomucoid trypsin inhibitors. They were strongly resistant to treatment with urea and weakly resistant to treatment with guanidine. The activation energies of HUK-1, -2, and -3 were found to by 1.17 X 10(4), 5.1 X 10(3), and 1.45 X 10(4) cal per mole, respectively. The Km values were estimated toward N-alpha-tosyl-L-arginine methyl ester (TAME), N-alpha-benozyl-L-arginine ethyl ester (BAEE), and N-alpha-benozyl-L-arginine methyl ester (BAME).

Fluorometric method for assay of kallikrein-like arginine esterases

The fluorometric method of Nash for determination of methanol was applied in assay of kallikrein-like arginine esterases using N-a-tosyl-L-arginine methyl ester (TAME) as substrate. The results obtained using this method corresponded well with those obtained in the usual colorimetric methods using hydroxamate, chromotropic acid, and 3-methyl-2-benzothiazolone hydrazone and the present method was more sensitive than these colorimetric methods.

Purification of kallikrein from cat submaxillary gland

Cat submaxillary kallikrein was purified from the water extract of the gland by 50-75% acetone fractionation, DEAE-Sephadex A-50 chromatography, Sephadex G-75 gel filtration and Ampholine isoelectric focusing. The final preparation gave the activities of 1260 KU/mg in vasodilator assay, 24.5 and 11.6 units/mg on BAEE and TAME esterolytic assay, respectively. Trasylol gave only weak inhibitory effect on this kallikrein. The isoelectric points of the kallikrein were in the range pH 4.2-5.0, and this kallikrein seemed to consist of several multiple forms with different pI values, like some other glandular kallikreins. It gave a single protein band in disc electrophoresis, while it migrated in retard and formed a broad one. This may be ascribable to the rich carbohydrate content in the kallikrein.