Response of urinary noradrenaline excretion to reserpine administration in normal and hypertensive subjects

Reserpine was administered in purpose to determine the "Noradrenaline store" in sympathetic nerve endings. The marked increase of urinary noradrenaline excretion was observed by reserpine 0.4 mg/day administration. Total amount of noradrenaline in urine for first three days of 0.4 mg/day of reserpine administration was considered as a good indicators of "Noradrenaline store". There was no difference of "Noradrenaline store" between normal and hypertensive subjects. The increase % of urinary noradrenaline was higher in labile hypertension than in established hypertension as well as in normal subjects. Though the relationship between "Noradrenaline store" or the increase % of noradrenaline and sympathetic nerve activity was not clear, it is suspected that the releasable noradrenaline in sympathetic nerve granule was higher in labile hypertension than in established hypertension or normal subjects.

Effect of actinomycin D on the expression of herpes simplex virus-common surface antigen in cells transformed by herpes simplex virus type 2

Using rabbit antiserum hyperimmune to herpes simplex virus (HSV) type 1, the expression of HSV-common surface antigen(s) was studied by indirect immunofluorescence tests in cells transformed by HSV type 2 and in derived tumor cells. The following results were obtained. (i) Antiserum to HSV type 1 reacted specifically with surface antigen present on the plasma membrane of both HSV type 2-infected and HSV type 2-transformed hamster cells. (ii) The expression of this antigen was enhanced in the absence of active protein synthesis in transformed cells, but not in tumor cells, after culture for 3 to 5 h at 37 degrees C. (iii) This enhancement of expression was maintained for 20 h in the presence of actinomycin D, but this prolonged expression required active protein synthesis. (iv) The enhancing effect observed in the presence of actinomycin D continued for some time after removal of the drug, for example, for 20 h after 5 h of treatment with 2 microgram/ml of actinomycin D per ml. Actinomycin D had no detectable effect on antigen expression in tumor cells. (v) The protease inhibitor antipain inhibited the actinomycin D-enhanced expression without causing significant cell damage but did not modify the transient enhanced expression of antigen when cells were seeded in the absence of actinomycin D. These results indicate that in transformed cells antigen expression can be enhanced in at least two ways.

Steroid specificity of human placental 5-ene-3 beta-hydroxysteroid oxidoreductase

The properties of 5-ene-3 beta hydroxysteroid oxidoreductase (3 beta-HSD) from human placental homogenates were studied in vitro. The apparent Michaelis constants for 3 beta-HSD with the substrates pregnenolone (delta 5P) and dehydroepiandrosterone (DHA) were 170 nM and nM respectively. The optimal pH for both these substrates was between 10 and 12. With NAD as the substrate, the Km for the pregnenolone was 20 microM and for DHA, 17 microM. The activity of 3 beta-HSD was inhibited by various steroids. Competitive inhibitors (pregnenolone substrate) included: ethynylestradiol (inhibition constant Ki=7.3 nM), DHA (Ki=46 nM), estradiol-17 beta (Ki=46 nM), cholesterol (Ki=0.68 microM) and 16 alpha-hydroxydehydroepiandrosterone (16 alphaOHDHA) (Ki=2.2 microM). When the substrate was DHA, competitive inhibition occurred with the following steroids: ethynylestradiol (Ki=6.4 nM), estradiol-17 beta (Ki=69 nM), pregnenolone (Ki=91 nM), cholesterol (Ki=1.3 microM) and 16 alphaOHDHA (Ki=1.9 microM). 4-Ene-3-ketosteroids such as androstenedione, progesterone (delta 4P), norethindrone and chlormadinone acetate acted as noncompetitive inhibitors towards both substrates.

Fibrinolytic States in a Patient with Congenital Deficiency of Alpha 2-Plasmin Inhibitor

A patient with congenital deficiency of α2-plasmin inhibitor (α2PI) was studied for his fibrinolytic system. The patient’s whole blood clot formed in vitro was lysed rapidly in several hours on incubation. This accelerated in vitro fibrinolysis was blocked by an addition of purified α2PI. In spite of the accelerated in vitro fibrinolysis, the increases of fibrinogen/fibrin degradation products and Fragment A were not detected when the blood was mixed with tranexamic acid-aprotinine mixture immediately after drawing blood, suggesting no increased in vivo fibrinogenolysis. When the patient’s citrated plasma was incubated in vitro, no or little progressive degradation of fibrinogen was observed in spite of the accelerated conversion of native Glu-plasminogen to modified Lys-plasminogen in the patient’s plasma. When the patient’s plasma was clotted by recalcification, fibrin formed was rapidly lysed. These results may suggest that α2PI is effective in inhibiting fibrinolysis but other protease inhibitors in plasma such as α2-macroglobulin are ineffective in inhibiting fibrinolysis although they are effective in inhibiting plasmin in plasma milieu thereby prevent fibrinogenolysis. Deficiency of α2PI in this patient may have led to uninhibited in vivo fibrinolysis resulting in friable hemostatic plugs causing severe hemorrhagic tendency.

Measurement of plasma renin concentration using exogenous human renin substrate in normal subjects: correlation with plasma renin concentration and plasma aldosterone concentration

Measurement of plasma renin concentration (PRC) was done in normal subjects at rest and under acute stimulation of renin release under unrestricted sodium intake. Concurrent measurements of plasma renin activity (PRA) and plasma aldosterone concentration (PA) were carried out. The mean values of PRC at rest and after stimulation of renin release were 12.8 +/- 1.3 (SEM) and 21.7 +/- 4.4 (SEM) ng AT I/ml/h, respectively. These corresponded to renin contents of 3.4 +/- 0.34 (SEM) X 10(-5) Goldblatt units and 5.8 +/- 0.36 (SEM) respectively. The mean percent increase of PRC (82.1 +/- 19.3 (SEM)) %) was almost indentical to that of PA (81.5 +/- 16.4 (SEM) %), but differed from that of PRA (269 +/- 83.1 (SEM) %). A very high correlation between concurrent PRC and PA (r = 0.92, P less than 0.001) was found in normal subjects at rest and under acute stimulation of renin release. A good correlation between PRC and PRA (r = 0.85, P less than 0.001) was also observed. However, a higher correlation between percent increases of PRC and PA (r = 0.92, P less than 0.001) than that of PRA and PA (r = 0.80, 0.01 less than P less than 0.005) was found. Results show that PRA is a good index of the renin content in plasma in normal subjects at rest and PRC reflects actual renin concentration in plasma at rest as well as under stimulation of renin release.

Ureotelism and ammonotelism in trypanosomatids

According to their genera, trypanosomatids excrete urea, ammonia, or both. Species of Herpetomonas and Trypanosoma are ammonotelic. Species of Leishmania, Leptomonas, Crithidia, and Blastocrithidia can be ureotelic, ammonotelic, or both, depending on growth media composition.

Release of arachidonic acid from human platelets. A key role for the potentiation of platelet aggregability in normal subjects as well as in those with nephrotic syndrome

Low (nonaggregating) concentrations of collagen that potentiate platelet aggregation did not induce the formation of measurable amount of malondialdehyde (MDA) but released small but significant amounts of radioactivity from 14C-arachidonic acid-labeled platelets. A major portion of the radioactive compounds released by nonaggregating concentrations of collagen existed as arachidonic acid and a minor part as thromboxane B2. The nephrotic syndrome enhances platelet aggregability, and this effect is abolished by correcting hypoalbuminemia in vitro and in vivo by the addition of albumin, which is the main carrier for free fatty acids, including arachidonic acid. Human albumin (fatty acid free) inhibited collagen-induced aggregation, MDA formation, and release of the radioactivity from 14C-arachidonic acid-labeled platelets in normals as well as in those with nephrotic syndrome. These data support our hypothesis that the main mechanism responsible for the potentiation of platelet aggregation is the release of arachidonic acid from platelet membrane phospholipids via the activation of phospholipase A2. Furthermore, enhanced platelet aggregation in the nephrotic syndrome was at least partly attributable to an increased availability of arachidonic acid released secondary to hypoalbuminemia. Albumin inhibits aggregation probably by binding to released arachidonic acid preventing arachidonic acid from being metabolized to potent aggregating substances, endoperoxides and thromboxane A2. The mechanism of release of arachidonic acid may play a key role in the potentiation of platelet aggregability in normals as well as in pathologic conditions such as the nephrotic syndrome.

Inhibition of fetal adrenal 21-hydroxylase by naturally occurring steroids

Inhibitory effects of naturally occurring steroids on 21-hydroxylase activity were determined by measuring the initial conversion rate of 17-hydroxyprogesterone (17alpha-hydroxy-4-pregnene-3, 20-dione) to 11-deoxycortisol (17alpha, 21-dihydroxy-4-pregnene-3, 20-dione) in incubation experiments with the microsomal fraction (10,000--105,000 X g percipitate) of the human fetal adrenal gland. The apparent Michaelis constant (Km) for conversion of 17-hydroxyprogesterone was 13.3 X 10(-6)M. Human fetal adrenal 21-hydroxylase was inhibited by some of the steroids produced in the feto-placental unit. The following steroids acted as competitive inhibitors of the reaction; progesterone (Ki = 20.0 X 10(-6)M), 11-deoxycortisol (Ki = 87.5 X 10(-6)M) and estradiol-17beta (Ki = 87.5 X 10(-6)M). The most potent inhibitor among the estrogens was estradiol-17beta.

Inhibition of platelet aggregation by protease inhibitors. Possible involvement of proteases in platelet aggregation

The possible participation of proteases in human platelet aggregation was explored using various protease inhibitors and substrates. Protease inhibitors used included naturally occurring inhibitors of serine proteases and synthetic inhibitors that modify the active site of protease. Substrates used were synthetic substrates for the trypsin type as well as for the chymotrypsin type of protease. All these inhibitors and substrates inhibited platelet aggregation and serotonin release induced by ADP, collagen, epinephrine, or thrombin. In ADP- and epinephrine-induced platelet aggregation the second phase of aggregation was most efficiently inhibited. The inhibitors suppressed the formation of malondialdehyde during platelet aggregation. Release by aggregating agents of arachidonate and its metabolites from indomethacin-treated platelets as well as nontreated platelets was also inhibited. The inhibitors apperar to interact with stimulated platelets but not with unstimulated platelets. These observations suggest that the interaction of an aggregating agent with its platelet receptor activates a unique precursor serine protease that in turn activates platelet phospholipase to liberate arachidonic acid (the precursor of the potent platelet aggregating agent thromboxane A2) from platelet phospholipids.

Distribution of cold-insoluble globulin in plasma and tissues

Cold-insoluble globulin is normally present in plasma and serum at concentrations of 27.52 +/- 4.60 and 23.46 +/- 5.18 mg/dl, respectively (means +/- SD). The concentration of CIg in blood samples was significantly decreased in DIC syndromes (14.69 +/- 6.55 mg/dl; p less than 0.001). A strong, positive correlation was found with AT-III (r = 0.68) and a less striking one with Plg. Although alpha 2-PI was shown to be significantly decreased in DIC syndromes (p less than 0.001), a weak, inverse correlation was found between CIg and alpha 2-PI (r = -0.29). Immunologically cross-reactive substances were found to be widely distributed in association with the cells and tissues of mesenchymal origin, including fibroblasts, adipose cells, smooth muscle cells, and basement membranes. The glomerular basement membrane was an exception and is currently believed to be of different origin. In the kidney, fluorescence was found in the mesangium. Cold-insoluble globulin is also present as a component of cryofibrinogen that forms a solid gel at low temperatures. Sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed that CIg in this fraction was rather homogeneous. Although closely migrating doublets were occasionally seen in the 440,000-dalton region on gels of unreduced samples, monomeric derivatives with a molecular weight of 220,000 or less, which have been claimed to occur in circulating plasma, were not observed. Thus, intact dimeric CIg appears to be the form of the molecule that complexes with fibrinogen. Cold-insoluble globulin is the fraction that was shown to exist as an independent entity from fibrinogen at an ambient temperature by immunoelectrophoresis and ultracentrifugation. However, very rapid formation of highly polymerized complexes in the sol phase at low temperatures was manifested by the finding of a sharp increase in light-scattering intensity using the technique of quasielastic light scattering. A control study on a mixture of normal CIg and fibrinogen disclosed no appreciable change in the temperature range between 37 and 8.5 degrees C. A comparative study on a mixture of cryofibrinogen-derived CIg and normal fibrinogen revealed an intermediate light-scattering pattern. After 2 hr at 8 degrees C, this mixture reached a state of equilibrium, where no further polymerization occurred. The secondary structures of normal and cryofibrinogen-derived CIg, determined by circular dichroism, showed no appreciable difference. A noteworthy finding was the almost complete absence of alpha-helices and a relatively high proportion of beta-structure in both forms of CIg. Amino termini of the fibrinogen moiety of cryofibrinogen were found to consist of alanine, tyrosine, and a small quantity of aspartic acid, consistent with the NH2 terminal moiety composition of normal fibrinogen but not of soluble fibrin monomer complex.

Abnormal plasminogen. A hereditary molecular abnormality found in a patient with recurrent thrombosis

A patient who suffered a recurring thrombosis over the last 15 yr has been investigated. The only abnormality found in this patient was a significantly depressed level of plasminogen activity in plasma. In spite of the depressed plasminogen activity, the patient was found to have a normal level of plasminogen antigen concentration. It was calculated that the activity per milligram of plasminogen of the patient was approximately one-half the values of normal subjects. The same discrepancy between biological activity and antigen concentration was found in the other members of the kindred. A niece was found to have practically no plasminogen activity but possessed a normal concentration of plasminogen antigen. Both her parents were found to have approximately half the normal plasminogen activity and normal antigen levels. These studies suggested that the molecular abnormality was inherited as an autosomal characteristic, and the family members who had half the normal levels of activity with normal plasminogen antigen were heterozygotes whereas the one with practically no plasminogen activity was homozygote. Subsequent studies showed that the pattern of gel electrofocusing of purified plasminogen of the heterozygotes consisted of 10 normal bands and 10 additional abnormal bands, each of which had a slightly higher isoelectric point than each corresponding normal component. This indicates that plasminogen of the heterozygote is a mixture of normal and abnormal molecules in an approximately equal amount, which was substantiated by active site titration of purified plasminogen preparations obtained from the propositus and a normal individual. The gel electrofocusing pattern of the homozygote consisted of abnormal bands only. The defect is a hereditary abnormality of plasminogen.

Biosynthetic pathways for corticoids and androgen formation in human fetal adrenal tissue in vitro

Eleven incubations of minced human fetal adrenal tissue from two fetuses at midtrimester of pregnancy terminated for socio-economic reasons, were performed for different periods of time with labelled pregnenolone, progesterone, 17alpha-hydroxyprogesterone and deoxycorticosterone (DOC). The order of magnitudes of enzyme activity when progesterone was used as a substrate and incubated with midterm fetal adrenals was 17alpha-hydroxylase, 21-hydroxylase and 16alpha-hydroxylase. The activity of 3beta-hydroxysteroid dehydrogenase and delta5-4 isomerase was almost negligible as compared to other enzymic activities as mentioned above. Similar biosynthetic pathways for adrenal corticoids formation were observed in human fetal adrenals as reported in human adults and animals; once progesterone was converted into DOC, further 17alpha-hydroxylation did not take place.