Clinical Use of I.C.I. 50172 as an Antidysrhythmic Agent in Heart Failure

I.C.I. 50172 was used to slow the ventricular rate when conventional treatment had failed in 19 patients. All were either in congestive cardiac failure or in the immediate postoperative period following valve replacement. The ventricular rate was controlled in seven out of eight patients with atrial fibrillation, in six out of nine patients with supraventricular tachycardia, and in two patients with sinus rhythm. Important side-effects were not seen.     

Practolol in Treatment of Supraventricular Cardiac Dysrhythmias

Practolol (I.C.I. 50172) was used to treat supraventricular dysrhythmias in 32 patients with a rapid ventricular rate and with heart disease of varied aetiology. In 26 patients the average reduction in ventricular rate was 75 per minute, while immediate reversion to sinus rhythm occurred in three patients. The slowing effect was mainly due to a direct action on the atrioventricular node. The effectiveness of practolol was unrelated to the type of dysrhythmia or its aetiology. No serious adverse clinical effects were noted.     

Mechanism of action of βadrenergic receptor blocking agents in angina pectoris: Comparison of action of propranolol with dexpropranolol and practolol

The effect on exercise tolerance of racemic propranolol has been assessed in eight angina pectoris patients and compared with that of dexpropranolol (the dextro isomer of propranolol), practolol (I.C.I. 50172), and saline. Dexpropranolol has the same local anaesthetic action as propranolol with negligible β-adrenergic receptor blocking activity, while practolol is a cardio-selective β-adrenergic blocking agent which does not have local anaesthetic activity.Saline and dexpropranolol had no significant effect on exercise time; racemic propranolol and practolol improved exercise tolerance in six subjects, the response to the two drugs being very similar in individual patients. It was concluded that the beneficial effect of propranolol in angina pectoris results from its action as a β-adrenergic receptor blocking agent and is not due to its local anaesthetic, or quinidine-like, activity.     

Preliminary Clinical Assessment of I.C.R.F. 159 in Acute Leukaemia and Lymphosarcoma

I.C.R.F. 159, a new antitumour agent, has been assessed in six patients with acute leukaemia and three with lymphosarcoma. In all but two there was a considerable fall in circulating primitive cells, and in one there was bone-marrow evidence of a partial remission. Severe toxic effects were seen in only one case; they consisted of alopecia and gastroenteritis. It is suggested that I.C.R.F. 159 is worth further examination in all forms of acute leukaemia and lymphosarcoma.     

Proteolysis of procollagen I.

1. Digestion of procollagen I which trypsin, pepsin or pronase performed at 20 degrees C causes the release of acidic non-collagenous fragments and hydroxyproline-rich fraction. Enzymatic proteolysis performed at 41 degrees C (above the temperature of denaturation) results in degradation of procollagen I to low-molecular peptides. 2. The hydroxyproline-rich fraction obtained by limited proteolysis of procollagen I with pepsin (at 20 degrees C) contains a material corresponding to alpha and beta subunits of tropocollagen. Reduction of the hydroxyproline-rich fraction released by trypsin or pronase (at 20 degrees C) causes the appearance of polypeptides similar to pro-alpha subunits.     

Periodic binding of troponin C.I and troponin I to tropomyosin-actin filaments

We investigated the distribution of troponin C.I and troponin I along tropomyosin-actin filaments by immunoelectron microscopy and found that anti-troponin I antibody formed transverse striations at 38 nm intervals along the bundle of filaments of both troponin C.I-tropomyosin-actin and troponin I-tropomyosin-actin. Since the length of 38 nm corresponds to the repeating period of filamentous tropomyosin along actin double strands, the present study indicates that troponin I is located at a specific region of each tropomyosin, suggesting that a specific interaction between troponin I and tropomyosin is involved in determining the periodic distribution of troponin I along tropomyosin-actin filaments.     

Interaction of troponin C and troponin C fragments with troponin I and the troponin I inhibitory peptide.

We have quantitated the interactions of two rabbit skeletal troponin C fragments with troponin I and the troponin I inhibitory peptide. The calcium binding properties of the fragments and the ability of the fragments to exert control in the regulated actomyosin ATPase assay have also been studied. The N- and C-terminal divalent metal binding domains of rabbit skeletal troponin C, residues 1-97 and residues 98-159, respectively, were prepared by specific cleavage at cysteine-98 and separation by gel exclusion chromatography. Both of the troponin C fragments bind calcium. The calcium affinity of the weak sites within the N-terminal fragment is about an order of magnitude greater than is reported for these sites in troponin C, suggesting interaction between the calcium-saturated strong sites and the weak sites. Stoichiometric binding (1:1) of the troponin I inhibitory peptide to each fragment and to troponin C increased the calcium affinities of the fragments and troponin C. Complex formation was detected by fluorescence quenching or enhancement using dansyl-labeled troponin C (and fragments) or tryptophan-labeled troponin I inhibitory peptide. The troponin C fragments bind to troponin I with 1:1 stoichiometry and approximately equal affinities (1.6 x 10(6) M-1) which are decreased 4-fold in the presence of magnesium versus calcium. These calcium effects are much smaller than is observed for troponin C. The summed free energies for the binding of the troponin C fragments to troponin I are much larger than the free energy of binding troponin C. This suggests a large positive interaction free energy for troponin C binding to troponin I relative to the fragments.(ABSTRACT TRUNCATED AT 250 WORDS)     

Additional PKA phosphorylation sites in human cardiac troponin I.

We used mass spectrometry to monitor cAMP-dependent protein kinase catalysed phosphorylation of human cardiac troponin I in vitro. Phosphorylation of isolated troponin I by cAMP-dependent protein kinase resulted in the covalent incorporation of phosphate on at least five different sites on troponin I, and a S22/23A troponin I mutant incorporated phosphates on at least three sites. In addition to the established phosphorylation sites (S22 and S23) we found that S38 and S165 were the other two main sites of phosphorylation. These 'overphosphorylation' sites were not phosphorylated sufficiently slower than S22 and S23 that we could isolate pure S22/23 bisphosphorylated troponin I. Overphosphorylation of troponin I reduced its affinity for troponin C, as measured by isothermal titration microcalorimetry. Phosphorylation of S22/23A also decreased its affinity for troponin C indicating that phosphorylation of S38 and/or S165 impedes binding of troponin I to troponin C. Formation of a troponin I/troponin C complex prior to cAMP-dependent protein kinase treatment did not prevent overphosphorylation. When whole troponin was phosphorylated by cAMP-dependent protein kinase, however, [(32)P]phosphate was incorporated only into troponin I and only at S22 and S23. Mass spectrometry confirmed that overphosphorylation is abolished in the ternary complex. Troponin I bisphosphorylated exclusively at S22 and S23 troponin I showed reduced affinity for troponin C but the effect was diminished with respect to overphosphorylated troponin I. These results show that care should be exercised when interpreting data obtained with troponin I phosphorylated in vitro.     

Inhibition of factor I by diisopropylfluorophosphate. Evidence of conformational changes in factor I induced by C3b and additional studies on the specificity of factor I

The factor I-mediated cleavage of C3b, using factor H as a cofactor was completely inhibited by diisopropylfluorophosphate (DFP) when factor I and C3b were incubated with DFP before the addition of factor H. Inhibition, although to a lesser degree, was observed when factor H was present during DFP-exposure. No inhibition in factor I activity was seen when factor I and H were incubated with DFP either alone or together. It was also demonstrated that the 38-kDa subunit of factor I bound radiolabeled DFP when factor I and C3b together were exposed to DFP. These observations suggest that factor I interacts with C3b in a manner that exposes its catalytic site to DFP, an interaction that is independent of factor H. The inhibitory effect by DFP on factor I led us to further investigate the factor I cleavage products of iC3b, inasmuch as previous reports were ambiguous as to whether digestion occurs in the presence of DFP. Digestion of C3b bound to activated thiol Sepharose (ATS-C3b) in the presence of factor H at low pH and ionic strength and in serum by complement activation produced C3d,g-like fragments with apparent molecular mass of 41 and 43 kDa. These fragments were shown to have three different N-terminal and two different C-terminal ends. The major fragments had N-terminal sequences starting with Glu933, as shown by sequence determination. Traces of fragments extending beyond this point were also found, shown by Western blot analysis using a panel of mAb previously shown to bind to epitopes exposed within a region of C3 spanning residues 929 to 943, as well as a shorter fragment starting with Glu938. When digestion of C3b is carried out in the presence of DFP, the factor I level necessary for digestion is elevated and may explain how the first two cleavages producing iC3b but not the following giving C3d,g, can occur. The finding of several factor I cleavage sites in the C3d,g region of C3 demonstrates that factor I has a broad specificity, mainly for arginyl bonds. It has also been shown to digest a lysyl bond exposed in ATS-bound C3b.     

Ultrastructures and interactions of complement factors H and I.

The human complement regulatory protein, factor H, was examined by high resolution transmission electron microscopy. Results of electron microscopy confirm hydrodynamic analysis and indicate that factor H is a monomer of M(r) approximately 155,000. Factor H is an extended flexible molecule with a contour length of 495 A and a cross-sectional diameter of 34 A. Most images of factor H indicate that its polypeptide chain typically folds back on itself with the result that the average length of a factor H molecule is about half its contour length. Only one end of factor H associates with C3b. When bound to C3b, factor H still shows considerable conformational flexibility. Factor I is a bilobal protein of 130 A in length, and its two globular parts have maximal diameters of 54 and 49 A. The results establish that factor I is a two domain protein where the smaller subunit is a protease and the larger one is involved with binding C3b. Factor I binds C3b with a one-to-one stoichiometry in an ionic strength-dependent fashion. In the absence of sodium chloride an affinity constant of 5.7 x 10(5) M-1 was determined for factor I interaction with C3b. Whereas the Scatchard plot of factor I binding to C3b in the absence of factor H is linear, in the presence of factor H a curvilinear graph is obtained. The strong binding sites on C3b for factor I have an affinity at least 15-fold higher in the presence of factor H than in its absence. The results of both electron microscopy and binding studies were combined to compose a scheme envisioning how factors H and I cooperate for the processing of C3b.     

Grass group I allergens (beta-expansins) are novel, papain-related proteinases.

Expansins are a family of proteins that catalyse long-term extension of isolated plant cell walls due to an as yet unknown biochemical mechanism. They are divided into two groups, the alpha-expansins and beta-expansins, the latter group consisting of grass group I allergens and their vegetative homologs. These grass group I allergens, to which more than 95% of patients allergic to grass pollen possess IgE antibodies, are highly immunologically crossreactive glycoproteins exclusively expressed in pollen of all grasses. Alignments of the amino-acid sequences of grass group I allergens derived from diverse grass species reveal up to 95% homology. It is therefore likely that these molecules share a similar biological function. The major grass group I allergen from timothy grass (Phleum pratense), Phl p 1, was chosen as a model glycoprotein and expressed in the methylotrophic yeast Pichia pastoris to obtain a post-translationally modified and functionally active allergen. The recombinant allergen exhibited proteolytic activity when assayed with various test systems and substrates, which was also subsequently demonstrated with the natural protein, nPhl p 1. These observations are confirmed by amino-acid alignments of Phl p 1 with three functionally important sequence motifs surrounding the active-site amino acids of the C1 (papain-like) family of cysteine proteinases. Moreover, the significantly homologous alpha-expansins mostly share the functionally important C1 sequence motifs. This leads us to propose a C1 cysteine proteinase function for grass group I allergens, which may mediate plant cell wall growth and possibly contributes to the allergenicity of the molecule.     

C6ORF66 is an assembly factor of mitochondrial complex I

Homozygosity mapping was performed in five patients from a consanguineous family who presented with infantile mitochondrial encephalomyopathy attributed to isolated NADH:ubiquinone oxidoreductase (complex I) deficiency. This resulted in the identification of a missense mutation in a conserved residue of the C6ORF66 gene, which encodes a 20.2 kDa mitochondrial protein. The mutation was also detected in a patient who presented with antenatal cardiomyopathy. In muscle of two patients, the levels of the C6ORF66 protein and of the fully assembled complex I were markedly reduced. Transfection of the patients' fibroblasts with wild-type C6ORF66 cDNA restored complex I activity. These data suggest that C6ORF66 is an assembly factor of complex I. Interestingly, the C6ORF66 gene product was previously shown to promote breast cancer cell invasiveness.     

Human mitochondrial complex I dysfunction.

In humans, complex I dysfunction has been observed in a high percentage of patients with mitochondrial myopathy. Analysis of mitochondria from these patients suggests the function and assembly of complex I is particularly susceptible to abnormalities of mitochondrial DNA, involving either point mutations of tRNA genes or major deletions. The evidence for a complex I defect in Parkinson's disease is accumulating, although the cause of this deficiency or the role it plays in the events that culminate in dopaminergic cell death remains unresolved.     

Treatment of patients with transitional cell carcinoma of the urinary bladder with intravesical poly I: Poly C effects on natural killer function

Summary Considerable interest has been focused on the use of interferon (IFN) and IFN-inducers as antineoplastic agents in humans. The current report will focus on the effect of intravesical administration of Poly I: Poly C on NK activity in patients with TCC of the urinary bladder. NK cytotoxicity was measured in 14 patients with primary TCC, 8 patients received Poly I: Poly C and 5 other patients received intravesical thiotepa. Blood samples were obtained prior to and 48 h following each drug treatment. A variation in the initial NK level determined prior to treatment was observed in the different TCC patients: 5 patients treated with Poly I: Poly C and 5 patients treated with thiotepa exhibited low NK activity prior to treatment, whereas the other 3 patients who were treated with Poly I: Poly C had high initial NK levels. Following drug treatment it was shown that a significant elevation in the NK cytotoxicity was only observed in patients treated by intravesical Poly I: Poly C who had low NK activity prior to treatment. No such effect was observed in patients treated with thiotepa or in patients treated with Poly I: Poly C who exhibited a high NK activity prior to treatment.     

Changes in plasma oestradiol-17beta, progesterone, testosterone, LH and fertility after treatment with I.C.I. 80, 996.

Fifty heifers were twice injected with I.C.I. 80, 996 and inseminated 72 h and 96 h after the second administration. Twenty eight of them (56%) became pregnant. Changes in plasma oestradiol-17 beta, progesterone and LH concentrations around the oestrus following the second injection were similar to those occurring in spontaneous oestrus. The pattern of testosterone secretion resembled that of oestradiol;-17 beta. The highest testosterone concentration (135 +/- 24 pg/ml) was measured on the third day after treatment with I.C.I. 80, 996.     

Biochemical studies with a new cytotoxic immunosuppressive agent, 3-acetyl-5-(4-fluorobenzylidene)-2,5-dihydro-4-hydroxy-2-oxothiophen (I.C.I. 47776)

1. A new cytotoxic agent, 3-acetyl-5-(4-fluorobenzylidene)-2,5-dihydro-4-hydroxy-2-oxothiophen (I.C.I. 47776), strongly inhibits protein and nucleic acid synthesis and, to a smaller extent, respiration in lymph-node cells and Landschütz ascites-tumour cells in vitro. 2. The activity of I.C.I. 47776 in vitro declines as the pH of the medium is increased and is inversely proportional to the concentration of serum in the medium. 3. The compound has no effect on the incorporation of leucine by a cell-free preparation from Landschütz ascites cells containing ATP and phosphoenolpyruvate. 4. I.C.I. 47776 stimulates glycolysis in suspensions of Landschütz ascites cells in the presence of excess of glucose but has no effect on glycolysis in suspensions of rat lymph-node cells. 5. I.C.I. 47776 markedly depresses ATP concentration in ascites cells in the absence of glucose but has no effect on the ATP concentration in the presence of glucose. The inhibition of protein synthesis by I.C.I. 47776 in ascites cells is, however, only partially reversed by the addition of glucose. 6. The ATP concentration of rat lymph-node cells incubated with I.C.I. 47776 in the absence of glucose is also markedly depressed but the addition of glucose increases the ATP concentration only slightly. Further, glucose has no effect on the inhibition of protein synthesis in lymph-node cells by I.C.I. 47776. 7. It is suggested that I.C.I. 47776 inhibits protein and nucleic acid synthesis in cell suspensions indirectly by acting as a mitochondrial poison. 8. The relevance of studies on the activity of I.C.I. 47776 in vitro to its cytotoxic and immunosuppressive action in vivo is discussed.     

La collaboration entre les taxonomistes et les groupes de travail de la C.I.L.B.

Summary The author examines in his report some aspects of the relations existing between the ecologists of the C.I.L.B. working teams and the taxonomists which collaborate with the identification centre, and between these taxonomists and the identification centre itself. The collaboration between taxonomists and ecologists must certainly be encouraged by the C.I.L.B., especially with regard to those biological control projects such as the Olive fly and the San Jose Scale, where behavioural caracters of the parasitic species may be determinant for their identification. Emphasis is given to the importance of the behavioural caracters in taxonomy and examples of this are reported. The collaboration between taxonomists and the identification centre of the C.I.L.B. would be favoured through the following: 1. The establishment of a card file at the C.I.L.B. head-quarters on the entomophagous insect species and their known hosts for a future publication of a synoptic catalog for the palaearctic region; 2. The institution of fellowships for taxonomists to study Museum collections; 3. The establishment of a homotype collection at the C.I.L.B. headquarters, which will constitute, with the file card system, a solid base for the future development of taxonomic work; 4. The reservation of a day for discussions about nomenclature questions at every C.I.L.B. meeting of taxonomists. The author recommends to address reprints concerning the taxonomy and systematic of entomophagous species to the C.I.L.B. headquaters (Entomologisches Institut der E.T.H., Universit?tstrasse 2, Zürich 6, Switzerland) for the establishment of an extensive reference collection to be used for publication of the bibliography on this subject.      

The first nuclear-encoded complex I mutation in a patient with Leigh syndrome.

Nicotinamide adenine dinucleotide (NADH):ubiquinone oxidoreductase (complex I) is the largest multiprotein enzyme complex of the respiratory chain. The nuclear-encoded NDUFS8 (TYKY) subunit of complex I is highly conserved among eukaryotes and prokaryotes and contains two 4Fe4S ferredoxin consensus patterns, which have long been thought to provide the binding site for the iron-sulfur cluster N-2. The NDUFS8 cDNA contains an open reading frame of 633 bp, coding for 210 amino acids. Cycle sequencing of amplified NDUFS8 cDNA of 20 patients with isolated enzymatic complex I deficiency revealed two compound heterozygous transitions in a patient with neuropathologically proven Leigh syndrome. The first mutation was a C236T (P79L), and the second mutation was a G305A (R102H). Both mutations were absent in 70 control alleles and cosegregated within the family. A progressive clinical phenotype proceeding to death in the first months of life was expressed in the patient. In the 19 other patients with enzymatic complex I deficiency, no mutations were found in the NDUFS8 cDNA. This article describes the first molecular genetic link between a nuclear-encoded subunit of complex I and Leigh syndrome.     

I. P. Pavlov's teacher of physiology I. F. Tsion (1842-1912)]

In 1866, at the C. Ludwig's laboratory, E. F. Cyon discovered n. depressor, and after C. Bernard's presentation he was awarded with the Montion Prize of the Paris Academy of Sciences. In 1867, together with his brother M. Cyon, he discovered nn. accelerantes of heart, which increase the heart rate when being stimulated. From 1868 to 1874 he was a privatdocent an professor of physiology at Saint-Petersburg University, where under his guidance I.P. Pavlov mastered the brilliant technique of vivisection experiment and accomplished his first works on the physiology of circulation and digestion. From 1872 to 1874 E. F. Cyon was physiology professor at Saint-Petersburg Medical-Surgical Academy. He published "Course of Physiology" in 2 volumes, the official speech "Heart and Brain" and others, proposed an original theory of inhibition, improved the reflex theory. He published 197 works, including 151 in German and French. I. P. Pavlov paid a worthy tribute to his teacher and continued the main direction of his investigations.     

C-value paradox in angiosperm plant species. I. Sensitivity to DNase I in species with different 2C DNA content.

The experimental conditions for DNAase I digestion in situ for plant nuclei have been presented. Cytophotometric measurements of DNA loss performed on Feulgen-stained nuclei of three species differing in 2C DNA, heterochromatin and condensed euchromatin contents have shown that the lower 2C DNA amount the higher is DNase I sensitivity. Heterochromatin and some fractions of euchromatin are DNase I resistant. Microdensitometric measurements along M chromosome in Vicia faba have demonstrated the sites hypersensitive to DNase I.