1) Defined media which allow heavy growth of 3 strains of group A streptococci have been developed. The medium consists of either a) 21 amino acids, glutamine, 6 vitamins, salts, purines, pyrimidines and glucose or b) 13 amino acids and 4 vitamins. 2) Cysteine is important both as an essential amino acid and as a reducing agent. As an amino acid only a small amount (10 μg ml) is needed and this can be substituted by an equivalent amount of cystine. As a reducing agent it can be replaced by ascorbic acid and less effectively by thiomalic or thioglycollic acids. Concentration of cysteine was critical for initiation of growth from small inocula. With less than 5 × 106 ml cells at least 350 μg ml cysteine HCl are needed for obtaining visible growth. 3) Pyridoxal was necessary in a medium of 13 amino acids and 3 vitamins (nicotinic acid, pantothenate, riboflavin) whereas in a complete medium (22 amino acids) no need for pyridoxal was found. Pyridoxal could be replaced by L- or DL-alanine.
During our study of the action of water-soluble
poly-a-amino acids on blood clotting (1), it was observed
that the basic poly-amino acids: poly-lysine
(2), poly-ornithine (3) and poly-arginine (3), retard
fibrinolysis of human clotted blood. A more detailed
analysis of this phenomenon was therefore undertaken.
Fibrinolytic activity of oxalated human plasma was
induced by mixing the plasma with a suspension of ,-
hemolytic streptococci (4, 5), by treatment with a cellfree
broth containing streptokinase (6), or by shaking
the plasma with chloroform (6, 7). The activated
plasma was then treated with the poly-amino acids
(prepared in this laboratory), and a fibrin clot obtained
by the addition of thrombin. The final mixtures
were incubated at 370 C for 15-24 hr to determine
-if lysis occurred. When the preparations used did not
interfere with fibrinolysis, dissolution of the clot occurred.
Inhibition of fibrinolysis was indicated by the
maintenance of the fibrin clot, obtained as described
*above, for 24 hr.
A typical experiment with poly-L-lysine and a
streptococei-activated plasma is described below.
Oxalated human plasma (0.5 ml) was mixed with a
suspension of 1-hemolytic streptococci (0.4 ml), and
the mixture added to 1 ml saline solution containing
40y poly-L-lysine hydrochloride. Clotting was induced
by adding 4 units of bovine thrombin (Upjohn Company)
in 0.1 ml saline with vigorous shaking. The clot
was incubated at 370 C for 24 hr. No visual change in
the clot was observed. In the control experiment where
the 1 ml poly-lysine solution was substituted by saline,
a complete lysis of the clot was evident within 30 min.
The fibrinolytic activity of plasma activated by Ihemolytic
streptococci was not inhibited either by the
neutral poly-DL-alanine (8) or by the acidic poly-Laspartic
(9) and poly-D-glutamic (10) acids up to
concentrations of 500y/ml final test mixture. The
basic poly-a-amino acids, poly-DL-lysine hydrochloiide
(average chain length n = 35) (2), poly-DL-ornithine
hydrochloride (n = 30) (3), and poly-DL-arginine sulfate
(n = 30) (3), on the other hand, prevented
fibrinolysis at concentrations greater than 30y40y/ml
test mixture.
In the presence of the basic poly-amino acids,
fibrinolysis Was inhibited equally well when the streptococcal
culture suspension was replaced (in the test
mixture) by a cell-free supernatant containing streptokinase.
Furthermore, it has been demonstrated that
the fibrinolytic activity of chloroform-treated plasma
and of menstrual blood was also inhibited by relatively
low concentrations of poly-DL-lysine and poly-
DL-arginine. It thus seems justified to assume that the
basic poly-amino acids are capable of inhibiting
hydrolysis of fibrin by plasma fibrinolysin (plasmin)
under the experimental conditions used.
Preliminary experiments indicated that the average
molecular weight of the basic poly-amino acids plays
a profound role in ther determination of their antifibrinolytic
properties. L-lysine monomer, as well as
L-lysyl-L-lysine (11), did not show any antifibrinolytic
activity up to a concentration of 750y/ml. A tetra-Llysine
showed slight antifibrinolytic activity at 750y/
ml, whereas poly-L-lysine of average chain length
n= 7, 35, and 100 showed distinct antifibrinolytic activity
at concentrations of 500y, 40y, and 35y/ml test
mixture, respectively.
No great difference was observed in the antifibrinolytic
activity of poly-L-, poly-D-, and poly-DL-lysine
of similar average molecular weights.
In our previous study on the action of water-soluble
poly-amino acids on blood clotting (1), it was demonstrated
that the acidic poly-amino acids, poly-D-glutamic
acid and poly-L-aspartic acid, as well as heparin,
are capable of neutralizing the anticoagulant activity
of the basic poly-amino acids. A similar relationship
was found to hold for the antifibrinolytic effect of the
basic poly-amino acids. Heparin, as well as poly-Laspartic
acid (n = 50), was found to obviate the antifibrinolytic
activity of poly-lysine. The neutralization
of the antifibrinolytic activity of the basic poly-amino
acids occurred when approximately equivalent concentrations
of the basie -and acidic poly-amino acids
were applied.
The ability of the basic synthetic peptides to inhibit rev,ersibly the. proteolytic activity of fibrinolysin resembles,
the antiproteolytic properties of some natural
peptides, such as the pepsin,inhibitor and the' trypsin
inhibitors (12). The interaction of the natural as well
as the synthetic peptides with the different proteolytic
enzymes is probably determined in both cases by some
specific groups present in the enzyme and the inhibitor,
as well as by the electrostatic forces prevailing
between the enzyme and the relatively high molecular
weight inhibitor. Further studies with the 'synthetic
amino acid polymers may contribute to our basic
knowledge of the mode of actlon of naturally naturally occurring
polypeptides on enzyme behavior.
The goal of the present study was to investigate whether spontaneous functional recovery following insult to the language-dominant hemisphere continues in the so-called "chronic stage," and if so, to examine its neuro-functional correlates. We used a longitudinal functional magnetic resonance imaging (fMRI) block design, where each young patient served as his/her own control. Specifically, we examined whether language functions differed significantly in two monitoring sessions conducted years apart, both in the chronic stage, where almost no functional changes are expected. We focused on a unique cohort of young brain damaged patients with aphasiogenic lesions occurring after normal language acquisition, in order to maximize the potential of plasticity for language reorganization following brain damage. The most striking finding was that the linguistic recovery of our patients was significant not just relative to their linguistic scores on initial testing (T1), but also in absolute te
Has the European Union (EU) succeeded in socializing citizens to support the democratic values it claims to promote? On the face of it, the prevailing skepticism precludes any expectation of a successful socialization of EU citizens to the EU values. Yet, according to the socialization hypothesis, citizens' support for these values is expected to increase as countries accumulate more years of the EU membership. Using survey data to isolate distinct dimensions of democratic values, we examine differences among countries in this regard, as well as changes within countries over time. Results confirm the socialization hypothesis, showing that support for democratic [...]
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Dates based upon notices at the end of sermons on f. 20r (593=1753), 48r (596=1756), 57v (555=1795). ; Ḳaplan, Yaʻaḳov . Lim, ha-Kohen, of Tartu (former owner, per stamp, f. 70v, etc.). ; קפלן, יעקב ב"ר משה ב"ר אליקים לים . הכהן, מתושבי העיר טרטו (בעלים, ע"פ חותמת בדף 07ב, ועוד). ; Reference to Kerem Shelomoh, per J. Brumer's notes. [...]
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K ( k (kaf/kof) pronunciation of - kvar (already)) k (kaf/kof), pronunciation of Bne Hes and Bne Ḵes , Kurdistan, Pronunciation Tradition , Tiberian Reading Tradition -ka suffix Morphology: Rabbinic[...]
