DERIVATIVES OF SOMATOSTATIN, AMINO ACIDS OR OLIGOPEPTIDES AND THEIR COMBINATION USEFUL FOR PROMOTING BODY GROWTH

Abstract: The following description sets forth new derivatives of somatostatins chemically modified in respect of endogenous somatostatin, whose administration to man and animals can significantly increase the body growth rate and index. Furthermore, L-amino acids, e.g., arginine, in particular arginine pyroglutamate, or oligopeptides, administered by the oral way in combination with the claimed derivatives of chemically modified somatostatins, produce a synergic effect on body growth.

Description: DERIVATIVES OF SOMATOSTATIN, AMINO ACIDS OR OLIGOPEPTIDES AND THEIR COMBINAΗON USEFUL FOR PROMOTING BODY GROWTH Field of the invention The present invention relates to new synthetic or semisynthetic derivatives of somatostatins, whose administration to man and animals can significantly increase the body growth rate and index, without substantially producing important side effects Furthermore, the administration of L-ammo acids, in particular L- arginine, preferably as arginine D , L-pyroglutamate , or of oligopeptides, in particular containing L-ammo acids, (such as L- argmine) and at least a D, L, or D,L-pyroglutamιc or D, L or D,L- aspartic acid residue, combination with said chemically modified somatostatins, can produce a synergic effect on the body growth. The pharmacological interaction with the growth mdeces is highly important both in the human field, for the treatment of pathologies associated with delayed or reduced development, and in the veterinary field, for enhancing, e.g., the growth cycles of livestock. Body growth is mainly regulated by the growth hormone (GH), synthesized in specific acidophilic cells, called somatotropic cells, constituting pituicytes to a large extent. GH secretion is regulated by the CNS and mediated by two hypothalamic factors: the growth hormone-releasing hormone (GHRH) factor and the somatotropin release inhibiting factor (SRIF) . The metabolic and growth promotion effects deriving from GH hormone are connected with its ability to stimulate the production of somatomedins which mediate somatotropic hormone activity (W.H. Daughaday, Clin. Endocrmol . Metabl., (1977), 6, 117). Several compounds, out of which neurotransmi t ters , hormones and metabolites, can alter hormone secretion by acting on the hypothala us and affecting the synthesis of GHRH or SRIF. Furthermore, physical exercise, stress, emotional excitement, prote - rich meals are normal stimuli capable of increasing hormone secretion. Prior art Several pharmacological approaches meant for stimulating body growth through mechanisms involving the secreation and activation of endogenous somatotropic hormone are already known. A treatment consists in the administration of the growth hormone itself, extracted from human matter, reproduced in vitro from cultured pituitary cells, or obtained by the recombinant DNA technique. The recombination derivatives known so far, defined as synthetic, are ethionyl-GH (Somatrem ^ ), which is much more antigemc than its natural analogue, obtained by extraction, and a recombination analogue having a lower lmmunogenic power, denominated somatotropm (Somatotropm^ 1 ' ) . GH and the derivatives thereof are absorbed by the intramuscular or subcutaneous route (see Goodman &. G lman's, The Pharmacological Basis of Therapeutics, 8th Ed., 1990, p. 13^1 ) • However, hypothyroidism and, frequently, antibodies production may follow the treatment with GH (D.R. Marshk, D.T. Liu, eds . , Banbury Report 29: Therapeutic Peptides and Proteins: Assessing the New Technologies, Cold Spring Harbor Lab., N.Y., 1988). Another treatment consists in the immunization to the growth hormone itself that, by feedback, may increase the endogenous somatotropic activity (D. Flint, AFRC News, 4th July, 1 89) . The active immunization of animals with peptides corresponding to GH epitopes may cause the production of antibodies capable of increasing the somatotropic activity of endogenous GH (A. Holder, J. Ivany, R. Aston. Molec. Immunol., (1987). 24, 143). The growth hormone may also be controlled by a direct action on the modulators of its biosynthesis. Structural analogues of the growth hormone-releasing hormone (GHRH) , composed of a chain of 29 amino acids and exhibiting the same activity as the natural hormone, have been recently synthesized. The administration of GHRH synthetic analogue to man by the intravenous route rapidly stimulates the growth hormone release. However, in a long-term treatment, GH secretion is pulsatile with simultaneous occurrence of inhibitory effects. Somatostatin ( Somatotropin Release Inhibiting Factor - SRIF) is produced by the pancreatic islands as a response to the many stimuli and hormones capable of provoking insulin and GH secretion. The hormone also inhibits several gastrointestinal secretions, e.g. of gastrin, gastric juice, secretin, CCK, vasoactive intestinal peptide (VIP) and digestive enzymes; possible consequences may be malabsorption and further side effects. Somatostatin is biosynthesized as a precursor of 116 amino acids, which are split by proteolysis into peptides consisting of lk or 28 ammo acid residues, the active form being that having 14 amino acids. The following schemes report the structure of somatostatin consisting of 14 amino acid residues, or somatostatm-l4 , available e.g., under the trademark Sigma ^ 9129 (cf. Biochemicals Catalogue, ICN, 1992- 1993. P. 1009): S S I I Ala-Gly-Cys-Lys-Asn-Phe-Phe-Trp-Lys-Thr-Phe-Thr-Ser-Cys 1 2 3 4 5 6 7 8 9 10 11 12 13 14 and the structure of somatostatin consisting of 28 ammo acids, also known as prosomatostatm or somatostatιn-28 (cf. Biolchemical Catalogue, ICN, 1992-1993. P- 1009): Ser-Ala-Asn-Ser-Asn-Pro-Ala- et-Ala-Pro-Arg-Glu-Arg-Lys- 1 2 3 4 6 7 8 9 10 11 12 13 14 S S I I -Ala-Gly-Cys-Lys-Asn-Phe-Phe-Trp-Lys-Thr-Phe-Thr-Ser-Cys 15 16 17 18 19 20 21 22 23 24 25 26 27 28 Biologically active, physiological somatostatins, of synthetic or extractive origin, are already known. Somatostatin produces pharmacological effects by linking to specific surface receptors of target cells. The influence of arginine on the glutamme brain levels and its action as an antagonist to depression-causing substances are known. Said effects are significantly strengthened when the ammo acid is administered as a salt with D,L-pyroglutamιc acid (P.M. Provenzano, A. Brucato. S. Gianguzza, A. Coppola, G. Orzalesi, R. Selleri, F. Innocenti, and I. Volpato, Arzneim. Forsch. /Drug Res . , (1977). 27(11). 8. p. 1533). Aspartate is found in very high concentrations in brain. It has excitatory effects on neurons. The existence of selective and high affinity aspartate uptake systems support its role as excitatory neurotransmitter (Goodman & Gilman's, 8th Ed. , pag. 257-259)- Technical Problem The inconveniences that may be brought about by the aforementioned treatments may be recapitulated as follows: a. great risks are involved in the pharmacological correction of GH lack, promoted by a substitutive treatment: i.e., the production of antibodies and a series of cascade reactions with consequent inhibition of the endogenous biosynthesis and simultaneous activation of the biosynthesis of inhibitors; b. similar mechanisms are generated by administering the main modulators, activators and inhibitors of the biosynthesis of the hormone itself, GHRH and SRIF; c. at the present state, a pharmacological aid derived from nutritional factors is very complex, since similar families of nutrients may simultaneously influence the biosynthesis of the hormone and of its main inhibitor. Summary Tt has surprisingly been found that some chemically modified somatostatins can promote body growth in man and animals and that the administration of said chemically modified somatostatins in combination with L-ammo acids in the L-form or in any mixture with their D-form, such as the racemic D,L form, in particular L- or D,L- arginine, or L- or D,L-aspartιc acid, or with oligopeptides produces a synergic effect. The chemical modifications with respect to the structure of endogenous somatostatins are represented by the substitution of glutamic acid residue (Glu) for the lysine residue (Lys) at the 4 position of somatostatms-l4 or at the 18 position of somatostatms-28, and/or in the substitution of serine (Ser) for the phenylalamne residue (Phe) at the 6 position, at the 7 position, or at both said positions of somatostatm-14, or at the 14 position, at the 20 position, or at both said positions of somatostatιn-28. The following chemical modifications were made to somatostatins having 14 or 28 ammo acids: carboxymethylation; polymerization in the presence of aldehyde derivatives; conjugation with polyam o acids or vith fatty acids, reductive alkylation, amid ation, maleilat on, carbamylation; carbethoxylation ; nitration, treatment with ormaldehyde, and photooxidation. Therefore, the present invention relates to the following derivatives of somatostatins: a) a synthetic derivative of somatostatm-1 , having a Glu residue at the 4 position (in substitution for Lys residue); a') a synthetic derivative of somatostatm-28, having a Glu residue at the 18 position (in substitution for Lys residue); b) a synthetic derivative of somatostatm-1 , having a Ser residue at the 6 position, at the 7 position, or at both said positions (in substitution for Phe residue); b' ) a synthetic derivative of somatostatm-28, having a Ser residue at the 20 position, at the 21 position, or at both said positions (in substitution for Phe residue) ; c) carboxymethylation product of somatostatins having 14 or 28 ammo acids ; d) polymerization product of somatostatin having 14 or 28 amino e) the conjugate of a somatostatin having 14 or 28 ammo acids with a polvamino acid; f) conjugate of a somatostatin having 14 or 28 ammo acids with at least a fatty acid; g) reductive alkylation product of a somatostatin having 14 or 28 ammo acids ; h) amidination product of a somatostatin having 14 or, 28 ammo acids; 1) aleilation product of a somatostatin having 14 or 28 ammo acids; j) carbamylation product of a somatostatin having 14 or 28 am o acids; k) carbethoxylation product of a somatostatin having 14 or 28 ammo acids; 1) nitration product of a somatostatin having 14 or 28 ammo acids; m) reaction product of a somatostatin having 14 or 28 am o acids with i ormaldehyde; n) photooxidation product of a somatostatin having 14 or 28 ammo acids ; o) acetylation product of a somatostatin having 14 or 28 ammo acids. It is a further object of the present invention to provide a method of preparation of the aforesaid somatostatins, the pharmaceutical compositions containing same and their use in all human and animal pathological and non-pathological situations, wherein body growth and development is to be promoted, in particular in the treatment for pathologies associated with a delayed or reduced body development of man and animals; in the veterinary field, in the situations wherein livestock growth cycles are to be accelerated. The present invention also includes the use of the claimed derivatives of somatostatins combined with at least a compound selected from the group consisting of L-ammo acids and any mixture thereof with their D-enantiomers , such as their racemic D,L mixtures, oligopeptides other than somatostatin derivatives containing at least a D, L or D,L- acid residue or at least a D, L or D,L aspartic acid residue and at least an L-amino acid residue, oligopeptides other than somatostatins containing at least a basic L-ammo acid residue, and tne salts thereof with pharmaceutically acceptable acids or bases, in all situations as defined above. Further objects of the present invention may be inferred from the present text. Detailed description of the invention Chemical-structural modifications according to the present invention, have been generally made in the 3~l4 region of somatostatιns-l4 or in 17-28 region of somatostatιns-28. The literature references cited in the present text are herein incorporated by reference. The abbreviations used herein to designate the amino acids and/or amino ac d residues present in the sequences of am o acids are as conventionally used e.g., in biochemistry texts, such as "Biochemistry", L. Stryer, W.H. Freedman and Co., 3rd edition, 1988, N . V .. pp . 20-22. Unless otherwise indicated, the configuration of amino acids and ammo acid residues present in the peptide sequences of somatostatins is L (for polyamino acids it may be L or D) . For the sake of simplicity, the somatostatins consisting of 14 or 28 amino acids are designated somatostatιns-l4 or -28, respectively. Somatostatins useful as starting materials for the preparation of the present somatostatin derivatives modified by treatment with chemical reagent are biologically active somatostatins, i.e. exhibiting the physiological activity typical of endogenous somatostatin, and can be obtained e.g. by synthesis, by extraction of animal tissue (e.g. mammal tissues, such as bovine or porcine extractive somatostatins), or by reco binant DNA tecnique. The chemically modified somatostatin derivatives of the present invention are typically obtained by treating with chemical reagents endogenous somatostatins. Some examples of somatostatin derivatives according to the present invention are conveyed below: - a derivative of somatostatm-l4 selected out of the derivatives of formula (I) S S ( I ) Ala-Gly-Cys-X-Asn-Y-Z-Trp-Lys-Thr-Phe-Thr-Ser-Cys 1 2 3 5 6 7 8 9 10 11 12 13 14 or the corresponding derivative of formula (I) wherein Asn is replaced w th Asp, where: A) X is Glu; Y is Phe and Z is Phe; P, χ X is Lys; Y is Ser and Z is Ser; C) X is Lys; Y is Phe and Z is Ser; D) X is Lys; Y is Ser and Z is Phe; - a derivative of somatostatm-28 selected out of the derivatives of formula (II) : ( II ) Ser-Ala-Asn-Ser-Asn-Pro-Ala-Met-Ala-Pro-Arg-Glu-Arg-Lys- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 S . _ s I I -Ala-Gly-Cys-X- Asn-Y- Z -Trp-Lys-Thr-Phe-Thr-Ser-Cys 15 16 17 18 19 20 21 22 23 24 25 26 27 28 or the corresponding derivative of formula (II) wherein one or more Asn residues are replaced by Asp, where: A') X is Glu; Y is Phe and Z is Phe; B' ) X is Lys; \ is Ser and Z is Ser; C ) X is Lys; Y is Phe and Z is Ser; D' ) X is Lys; Y is Ser and Z is Phe. Among the derivatives of somatostatins of the present invention, particularly preferred are the derivatives of somatostatms-14 either synthetic, such as derivatives a), a'), b) and b') as defined above, and more particularly compounds A), B), C) and D) of formula (I), or semisynthetic, such as derivatives c) to o) , obtained by chemically modifying somatostatins having 14 am o acids. The synthetic derivatives of somatostatins of the present invention a), a') 4 b) and b') are prepared by total synthesis starting from the single am o acids constituting them, optionally in a suitably protected form, according to conventional methods, e.g., by suitably adjusting the known processes for the preparation of synthetic somatostatins. According to a typical embodiment of the present invention, the claimed synthetic somatostatins are prepared by automatized peptide synthesis on solid phase, according to the method described by B. Mamfield, Science, (1986), 232, 41- 47 (cf. also Biochemistry, L. Stryer, .H. Freedman and Co., 3rd edition, 1 ( N . , pp. 65-66) . The ammo acids used for the synthesis are already known, commercially available or, in any case, may be obtained by conventional methods. extractive somatostatins useful as starting materials for the present invention are for instance obtained as described by B.D. Noe , J. Spless, J.E. Rivier, and W. Vale, Endocπnol., (1979), 105, P- l4l0; in any case, commercially available somatostatins can be used as stdit g meteπals. The claimed derivatives of somatostatins obtained bj arboxymethylation are typically prepared by a reductive method, by causing a somatostatin consisting of 14 or 28 am o acids, preferably of 14 ammo acids, to react w th glyoxylic ac d in the presence of c\ anoboron hydride, typically according to the method described by T. Piao King, L. Kochoumian, L.M. Lichteriste , in Arch. Biochem Bioplws., (1977). 178 (2), 442-450. The resulting somatostatin derivatives contain one or more lysme residues, partially or entirely carboxy ethylated at their €-amino residues . S-carboxymethylated somatostatins, i.e. containing sulphur- carboxymethylated Cys residues (designated as Cys-S-carboxymethylated or Cys-S-CH2~C00H) , at the 3 position, 14 position, or at both said positions of the somatostatin consisting of 14 ammo acids, or at the 17 position, 28 position, or at both 17 and 28 positions of the somatostatin consisting of 28 amino acids can be for instance obtained according to the method of T.P. King, P.S. Norman, N. Toa, Iinmunochemistry , 11, 83 (1974). Reduction and carboxymethylation may be carried out in the presence of 6 M GUA, according to A.M. Crestfield et a l . , (A.M. Crestfield, S. More, J.H. Stem: "The preparation and enzymatic hydrolysis of reduced and S-carboxymethylated proteins", J. Biol . Chem. , (1 63 or 1969), 288, 622-627, or by treatment with DTT (dithio-threitol ) , then with lodoacetic acid, according to P.J.G. Butler et a l . (P.J.G. Butler, J.I. Hams, B.S. Hartley, R. Leberman: "The use of maleic anhydride for the reversible blocking of ammo groups in polypeptide chains", Biochem. J., (1969), 112, 679-689. According to a typical embodiment of the present invention, polymerized somatostatin derivatives are, e.g. , prepared by treating an endogenous, biologically active somatostatm-14 or -28, preferably having l4 amino acids, with an aldehyde, e.g., a dialdehyde, such as glutaraldehyde. The method adopted may be, e.g., as described by S. Avrameas, Immunochemistry , Pergamon Press", (I969), 6, 43~52- For example, somatostatin (e.g. extractive) is treated, in an aqueous medium, with glutaraldehyde, at a pH generally ranging from 6.0 to 8.0, preferably at a pH of about 6.7-6.9 (e.g. in a phosphate buffer), at a temperature ranging from about 4°C to about 4θ°C, typically at room temperature (+20°C/+25°C) . The reaction is complete in about 0.5 to 5 h, typically in 3 h. Glutaraldehyde is typically used in a stoichiometπc excess with respect to the amιno-NH2 groups of somatostatin (typically 10 " to 10 ~ - ) mol glutaraldeyde per 10 ~ -Vl0 ~ moles of -NH groups of somatostatin). According to a particular embodiment of the present invention, treatment with glutaraldehyde is followed by treatment of the reaction mixture with tyros e, preferably added in essentially the same molar excess as that of glutaraldehyde with respect to somatostatin. At the reaction end, glutaraldehyde excess is neutralized by treatment with sine, e.g. under the same reaction conditions adopted for the polymerization . The resulting polymerization product is preferably purified by dialysis, typically on membranes with a molecular exclusion limit (cutoff) of about 500 to 1,000 Daltons, preferably versus a buffer having a pH of 6.0 to 8.0, e.g., versus a buffer having a pH of 7-0 to 7 5. such as PBS (physiological solution/phosphate buffer). The dialysis, which is preferably carried out at a cool temperature, e.g. of about 4°C to about 10°C, allows the purification of the final product from glutaraldehyde. The resulting product exhibits a degree of polymerization preferably ranging from about 3 to about 6-8 repeating units. The polyamino acids useful for being conjugated with somatostatins according to the present invention typically contain from 2 to about 8-10 am o acids, having any configuration (D or L or a mixture thereof) and may be either homopolymers or heteropolymers . According to a typical embodiment of the present invention, somatostatins are conjugated with polyamino acids having one or more free basic groups, one or more free acidic groups, or mixtures thereof That is, said polyamino acids contain a further basic or acidic group addition to the α-ammo or α-carboxyl groups. The further basic or acidic groups are in the free state, not involved in the peptide linkage, available for the successive conjugation with somatostatins . Typical examples of basic groups are the free -NH ? groups, e.g. of lysine, and typical examples of acidic groups are the free -C00H groups, e.g. of glutamic acid. Several of said polyamino acids are commercially available or, in any case, may be obtained by conventional techniques. Typical polyaminoacids have a molecular weight e.g. from 600 to 10,000 Daltons, such as poly-L-glutamic acid, e.g. as sodium salt, e.g., having a molecular weight of about 600, poli-D,L-aspartιc acid having molecular weight of 2000-10,000 Daltons, and poly-L-lysme , e.g. having a molecular weight of about 1,000 to 4,000. According to a typical embodiment of the present invention, a somatostatin (e.g. extractive) having 14 or 28 amino acids, preferably 1 ammo acids, is treated with at least a polyamino acid containing free -NH2 groups, in the presence of a dialdehyde, such as glutaraldehyde. Also in this case, it is possible to follow the aforementioned method disclosed by S. Avra eas. For example, somatostatine (e.g. extractive), a polyamino acid containing free -NH2 groups, and glutaraldehyde are caused to react in an aqueous medium, at a pH generally ranging from 6.0 to 8.0, preferably at a pH of about 6.7 _ 6.9 (e.g. in a phosphate buffer), at a temperature ranging from about 4°C to about 4θ°C, e.g. at room temperature (+20°C/+25°C) . The reaction is complete in about 0.5 to 5 h, typically in 3 n - Typically, a mixture of somatostatin (e.g. extractive) and polyamino acid containing free -NH 2 groups, in an aqueous medium, is added with glutaraldehyde. Glutaraldehyde is typically used in a stoichiometπc excess of the -NH 2 groups of the polyamino acid (typically 1 to lO "5 mol glutaraldeyde per 10 ~ ^/10 ~ moles of -NH groups are used). At tht reaction end, glutaraldehyde excess is neutralized by treatment with lysine . e.g. under the same reaction conditions as adopted for the conjugation. The resulting conjugation product is preferably purified by dialysis under the conditions indicated above for polymerized somatostatins. As concerns the somatostatin polymerization or conjugation with polvammo acids in the presence of glutaraldehyde, reference is made also to \' . Zegers. K. Gerritse, C. Deen, l\ . Boersma, and E. Claassen, Journal of Immunological Methods (1990), 130, 195-200. The conjugation of somatostatins with compounds having free -C00H groups, e.g., polyamino acids or fatty acids, is carried out e.g. by treatment of a somatostatin (e.g. extractive) having 14 or 28 amino acids with at least a polyamino acid having one or more free -C00H gioups, or with at least a fatty ac d, in the presence of a carbodiimide. The conjugation is typically carried out in an aqueous medium, at a pH preferably ranging from about 5 to about 6 (e.g. at a pH of 5-5. in an acetate buffer), at a temperature generally ranging fio about 30°C to about 4θ°C, typically at 37 °C. The -COOH groups of the polyamino acid or fatty acid, activated by reaction with carbodiimide, react in particular with the free -NH ? groups of somatostatin, with formation of an amide bond. For example, the polyamino acid containing free -COOH groups (or the fatty acid) is treated with carbodiimide, in a stoichiometric excess in respect of the -COOH groups, in an aqueous medium, at a pH generally ranging from 8 to 10, at a temperature typically ranging from about 10°C to about 4θ°C, e.g. at 37°C. The resulting product is treated with somatostatin, in an aqueous medium, at a pH preferably r nging from about to about 6, (e.g. of 5-5. in an acetate buffer), at a temperature generally ranging from about 30°C to about 40 °C, typically at 37°C. The conjugates obtained are preferably purified by dialysis at a cool temperature, e.g. at about 4°C to 10°C. The carbodiimide is preferably a pharmaceutically acceptable carbodiimide, the reaction products thereof are also pharmaceutically acceptable, such as N-ethyl-N' (dimethylaminopropyl ) carbodiimide. Typical conjugation conditions in the presence of carbodiimide which can be followed are described by E.C. Beuvery, G.J.A. Speijerε, B.I.G. Lutz, D. Freudenthal, V. Kanhai , B. Haagmans, and H.J.G.M. Derks , in IABS/ HO/UCSF, Symposium on Use and Standardization of Chemically Defined Antigens, San Francisco, U.S., 1 8 ; Develop. Biol. Standard, S. Karger, ed., Basel (1986), vol. 63, pp. 117-128. The fatty acids useful for the preparation of somatostatin derivatives according to the present invention may be either saturated or unsaturated, such as, e.g., palmitic, oleic, stearic, linoleic acids. According to a further typical embodiment of the present invention, somatostatιn-l4 or -28, preferably having 14 ammo acids (e.g. extractive), is treated with at least a polyamino acid containing one or more free -SH groups, in the presence of a di thiobifunc tional reagent, such as N-succmιmyl-3- (2-pyπdyl-dιthιo)propιonate (SPDP). Typically, the method that may be followed is that described by D.A. Gadkari. H.A. Fields, and J.E. Maynard, in J. Virolog. Meth. , (1985), 10(3) . P- 215-24. The free -SH groups, i.e. those available for the conjugation of somatostatins with polyam oacids with -SH groups through a disulfide bridge, are typically supplied by cystem residues. Conjugation through disulfide bond can be for instance carried out at room temperature, e.g. at a pH of about 7-0-7.5, e.g. in PBS buffer. SPDP is typically in molar excess with respect to free -SH groups. In the preparation of somatostatins conjugated with polyamino acids of any type, the somatostatms/polyam o acids molar ratios preferably range from 1:2 to 1:5. which are essentially found in the resulting conjugates. In the preparation of conjugates of somatostatins with fatty acids, the somatostatins/fatty acids molar ratios preferably range from 1:2 to 1:5. which are essentially found in the resulting conjugates. The claimed somatostatin derivatives obtained by reductive alkylation, amidmation or maleylation of somatosta ins having 14 or 28 ammo acids are typically obtained by the methods described by B. Bizzini, A. lurpm, G. Carroger, . Raynaud, in Immunochemistry of tetanus toxin, effects of the modification of lysyl residues of tetanus toxin on its toxic and immunological activities, Proceeding 4th International Conference on Tetanus, Dakar, 1975 (or 1976) p. 1 5, Foundation Merjeux, Lyon. Reductive alkylation is typically a reductive methylation, carried out by treating somatostatin with formaldehyde and with a reducing agent such as NaBH[ι , thus affording methylated somatostatin. Reductive methylation conditions suitable for the present invention are also reported by J.P. Robinson et al . in The Journal of Biological Chemistry, 250, 7 3 ~7442 (1975); P.H. Stem et al . , Z. Immun . -Forsch. 145, 418 (1973). and G.E. Means, R.E. Feeney, Biochemistry, 7. 2192- 2201 (1968). Amidmation is typically accomplished treating somatostatin with e hylacetimidate hydrochloπde. Maleylated somatostatin is typically obtained by treating somatostatin with maleic anhydride. Maleylat g conditions suitable for the present scope are also reported by P.J.G. Butler et al in Biochem. J , 112, 679-689 (1969). The carbamylation of somatostatins having 14 or 28 aminoacids is typically carried out according to the method described by J.P. Robinson, J.B. Picklesimer, D. Puett, in Tetanus Toxin: the effect of chemical modifications on toxicity, immunogenicity and conformation. The Journal of Biological Chemistry, (1975). 250, 7 3 -7442 Accordingly, carbamylated somatostatins can be typically obtained by treating somatostatin with a cyanate, such as potassium cyanate. Reductive alkylation, amidmation, maleilation and carbamylation imply, in particular, modifications to one or more lysine residues of somatostatins . The carbethoxylation of somatostatins having 14 or 28 amino acids is, e.g., carried out according to the method described by P. Stem and H. Biel, in Modification of tetanus toxin with selective chemical reagents, Z. Immun. -Forsch. , (1973). 14 . 4l8. Carbethoxylated somatostatins are typically obtained treating somatostatins with ethoxyformic anhydride. The nitration of somatostatins is preferably carried out by treatment of a somatostatin having 14 or 28 ammo acids with tetramtromethane, e.g. according to B. Bizzini, A. Turp , M. Raynaud, Immunochemistry of tetanus toxin: the nitration of tyrosyl residues in tetanus toxin, Eur. J. Biochem., (1973). 39. 171-l8l . or, alternatively, following hoshland's method therein cited (Koshland D.E. , Karkhanis Y.D. & Latham H.T. , J. Am. Chem. Soc . 86, 1448-1450, 1964), according to which somatostatin is reacted with 2-hydroxy-5~nitro-benzyl bromide. Nitration comprises, in particular, chemical modifications to tryptophan residues of somatostatins. The treatment of somatostatins having 14 or 28 amino acids with formaldehyde is typically carried out according to the method described by H. Bizzim, M. Raynaud: La detoxification des toxmes proteiques par le f or el : mecanismes supposes et nouveaux developpements, Biochimie, (1974), 56, 297-303. Treatment for formaldehyde can be also accomplished according to J.P. Robinson et al , The Journal of Biological Chemistry, 250, 743 -7 42 (1975). before mentioned. The photooxidation of somatostatins having 14 or 28 ammo acids is carried out according to the method described by P. Stem, H. Biel, in Z. Immun. -Forsch, 145. 4l8 ibid. , (1973). according to which photooxidation can be carried out e.g. irradiating somatostatin with ultra-violet light in the presence of a photooxidation sensitizer, such as methylene blue. The acetylation of somatostatins having 14 or 28 ammo acids is typically carried out according to the method described by E. Habermann, in Discrimination between binding to CNS, toxicity and immunoreactivity of derivatives of tetanus toxin, Med. Microbiol. Immunol. , (1973). 159. 89-IOO. The chemical methods reported in the literature references hereinafter cited with regards to the preparation of the present somatostatin derivatives actually refer to proteic substances other than somatostatin. Of course, unless otherwise stated in the present text, said methods have to be adapted by the man skilled in the art, adjusting the amount of reactants and solvents as a function of the different molecular weight and different amount of reactive sites of somatostatin. The claimed somatostatin derivatives find application, in particular: a. in the human field, to correct growth defects; b. in zootechny, to accelerate livestock growth curves and to mcreae bod.v weight. In the treated subjects, administration of the claimed derivatives stimulates body growth without producing evident side effects. No alteration to the quality of livestock meat takes place. The derivatives of somatostatins according to the present invention are typically administered by the parenteral way, m particular by the intramuscular (l. .) or subcutaneous way (s.c). The claimed pharmaceutical compositions are prepared by conventional techniques, as reported, e.g., in Remington's Pharmaceutical Sciences, lδth Ed., 1990. They include at least a derivative of somatostatins according to the present invention, in a therapeutically effective quantity, in combination with one or more pharmaceutically acceptable excipients or diluents, or mixtures thereof. Particularly preferred are the preparations for injection, comprising at least a somatostatin derivative of the invention and at least a diluent, wherein said derivative is dispersed, dissolved or emulsified, e.g. water for injection, and optionally other excipients. The present preparations for injection can be, e.g. , in the form of vials for the simultaneous preparation of the liquid to be injected, c g comprising a first vial enclosing the somatostatin derivative in the solid form and a second vial enclosing the diluent to be added to the first vial immediately prior to administration. Sustained release preparations for injection are also preferred, which can be for instance prepared by methods analogous to those known for the preparation of the slow-releasing forms of insulin. The Applicants have surprisingly found that the administration of the aforementioned L-ammo acids optionally admixed with their D enantio ers, e.g. as D,L mixtures, and oligopeptides, in combination with the present derivatives of somatostatins, can synergically strengthen their effect. Furthermore, the administration of same in the salified form with pyroglutamic acid (herein abbreviated as Pyr) or with aspartic acid, promotes growth " to a significantly larger extent than the administration of ammo acids as free bases. Pyroglutamic acid and aspartic acid can be in the D or L forms or mixtures thereof; typically they are in the racemic form (D,L), abbreviated as D,L-Pyr and D,L-Asp. Preferably, the L-ammo acids useful as growth promoters are the natural ones, and are preferably basic (having other basic groups in addition to the C1-NH2 group), such as L-arginme and L-lysme. Out of the ammo acids to be combined with the present somatostatin derivatives, L-argmine is preferred, and the L-arginine salts with D , L-pyroglutamic acid or with D,L-aspartιc acid are particularly preferred; D,L-pyroglutamιc acid was known as a neurotrophic agent, and D,L-aspartιc acid as neurotransmitter, but their use as adjuvants to body growth stimulation was neither described nor suggested. Oligopeptides are preferably dipeptides, tripeptides and tetrapeptides, and contain natural L-ammo acids. They preferably contain at least a residue selected out of L-arginine, L-lysme and mixtures thereof. The oligopeptides containing at least a basic ammo acid contain in particular one or more residues of L-arginine, L-lysme or mixtures thereof. An example is Lys-Arg-Arg. To the Applicants' knowledge, the oligopeptides containing at least a pyroglutamic acid residue are novel and constitute a further object of the present invention. They are obtained by conventional methods. Said oligopeptides typically contain only one D, L or D,L pyroglutamic acid residue or one D, L or D,L aspartic acid residue, situated at the beginning of the ammo acidic sequence. Preferred examples are: D.L-Pyr-Arg-Arg D , L-Pyr-Arg-Arg-Arg D,L-Asp-Arg. The aforesaid L-amino acids, oligopeptides and salts thereof are preferably administered daily by the oral route, either as such or as pharmaceutical compositions, or, preferably, are directly added to the diet as dietary compositions or supplements, especially in the zootechnical field. The dietary supplement can be for instance a concentrated supplement (e.g. a premix) for mixing or blending with animal feed. The dietary composition may be e.g. feedstuff added with the aforesaid L-ammoacids and oligopeptides. The pharmaceutical compositions containing the aforesaid L-amino acids, oligodipeptides or salts thereof, combined with one or more ph a rmaceu t i c al ly ac cep table exc i p i en t s , p rep ared ac c o rd ing to conventional techniques , cons ti tute a further obj ec t of the present inven tion . The aforesaid L-ammo acids and oligopeptides may also be administered by injection; in this case, they are preferably administered after administration of the present derivatives of somatostatins, generally 6-8 hours after or 2k hourrs after somatostatin derivatives administration. Typically, the present derivatives of somatostatins are administered b\ the parenteral route, in combination with the aforesaid amino acids, oligopeptides, or salts thereof, which are administered by the oral route Typical dosages of the derivatives of somatostatins of the invention and of the aforesaid L-ammo acids and oligopeptides or salts thereof, as defined above, are reported below: A. Somatostatin derivatives: a. Use in the human field, by the parenteral route (typically subcutaneous or intramuscular) : the daily dosage rates correspond, e.g. , to the doses of somatostatin administered for treating giantism; the daily dose is preferably partitioned into one or more doses and repeated every 7-15 days. b. Use in the veterinary field, by the parenteral (typically s c ) wa : 0.001 to 2 mg per kg/bodyweight per day, as a single or repeated dose, depending on the animal species, typically once for poultry and rabbits, and every 15~30 days for swine, ov es and cattle, and every 7~ 15 days in man . The administration of a slow-releasing pharmaceutical form (e.g. analogous to the slow-releasing forms of insulin) is preferred. B. L-ammo acids and salts thereof, oligopeptides as defined above and salts thereof: in the human and veterinary fields: 5 to 50 mg/kg/bodyweight per day by the oral route (or 1 to 10 mg/kg/bodyweight per day by the l.m. route). ( . Treatment duration: it varies depending on the species; it lasts from 15 days to 3 months according to the results. In man, the treatment way be repeated in cycles, e.g., in yearly cycles. Experimental Part Example 1 - Preparation of D,L-pyroglutamic acid salt with L-arginine L-argmme was dissolved in little boiling water and added, still in the hot, with a concentrated aqueous solution of D,L-pyroglutamιc acid (1:1 molar ratio). The mixture was left the hot under stirring for some minutes, concentrated on rotary evaporator at a reduced pressure until total water removal. The residue was taken up three times with abs. ethanol, filtered and evaporated again, each time by the aforesaid method. Final yield was 8k% of the theoretical value. Example 2 - Preparation of a somatostatin derivative polymerized in the presence of glutaraldehyde (inactivated somatostatin) Reagents . Extractive somatostatm-14 (Sigma R 9129) (M.W.= 1637-9; 1 mg corresponds to 6.1 x 10 ' mole). Glutaraldehyde (M.W. = 100; 1 mg corresponds to; 1 x 10 " ^ mole) Tyr (M.W. = l8l ; 1 mg corresponds to 5-52 x 10 mole). L.\s (M.W. = lk β ; 1 mg corresponds to 6.85 x 10 mole). Process: A mixture of 10 mg of somatostatm-l4 (6.1 x 10 mole) + l H 2 0 5 ml PBS is added dropwise with glutaraldehyde (50 mg; 200 μl of a 25% solution, 0.6l x lO " ^ mole, corresponding to a 1:50 excess with respect to Lys). A precipitate forms The reaction mixture is left under stirring for about 5 minutes at the laboratory temperature. Then, it is added with I\r (100 μl of a 100 mg/ml Tyr solution), and left under stirring for 10 minutes at room temperature. The reaction is then blocked by Lys addition (68θ μl of a 2M lys solution). pH (6.25) was then adjusted to 6.95 by diluted NaOH addition. The reaction mixture is filtered on a 0.4 μm filter, stored at < k "C and used as such. Efficacy Treatment Control Six groups of rats during their growth stage (12 animals each group) were treated as follows. Experimental model: - group I • placebo animals; normal feeding conditions; - group II . animals treated subcutaneously only with a single dose of polymerized somatostatin (PS) according to Example 2; - group III : animals daily treated only with PCA-Arg (L-arginme D,L- piroglutamate, with a 1:1 arginine: piroglutamic acid molar ratio), by means of a gastric probe; - group IV : animals daily treated s.c. with a single dose of polymerized somatostatin (PS) according to Example 2, and also with PGA-Arg, per os , daily, for the duration of the treatment; - group V : animals treated s.c. with a single dose of polymerized somatostatin (PS) according to Example 2, and also with ASP-Arg (L- arginine D , L-aspartate , with a 1:1 argmine: aspartic acid molar ratio), per os , daily, for the duration of the treatment; - group VI : animals treated s.c. with two doses of polymerized somatostatin (PS) according to Example 2 (the first on day 0 and the second on day 10 from the beginning of the treatment), and also with PGA-Arg, by means of a gastric probe, daily, for the duration of the treatment. Treatment duration : 21 days. Ihe single dose of polymerized somatostatin was administered at day 0, and am oacids were administered 6-8 hours after polymerized somatostatin (PS) . Administered dosages: - Polymerized somatostatin (PS) : 0.005 mg/animal ; - PGA-Arg : 1 mg/animal/day per os ; - ASP-Arg : 1 mg/animal/day per os . Tested parameters: - weight variation; - feedstuff intake. Results The results are hereinbelow reported in Tables 1 and 2. Table 1 reports the body weight values at day 0, 7, lk and 21. TABLE 1 Group Treatment Body weight (g) Day —> 0 7 14 21 I Placebo 92 140 177 225 TI PS s.c. 93 140 195 259 III PGA-Arg 92 140 183 238 IV PStPGA-Arg 92 140 198 275 V PS+ASP-Arg 93 140 205 280 VI 2xPStPGA-Arg 93 140 200 285 1 Averages values E χ /n PS = Polymerized Somatostatin PGA-Arg = arginine pyroglutamate ASP-Arg = arginine aspartate Table 2 reports the percent body weight increase with respect to the 0 day weight. The amounts in brackets refer to the difference of percent weight increase with respect to placebo group I. TABLE 2 Group Treatment Percent body weight increase Day —> 7 14 21 I Placebo 52.1 92.4 144.6 II PS s.c. 50-5 109-6 (17-2) 178.5 (33-5) III PGA-Arg 52.1 98.9 (6.5) 158.6 (14.0) IV PS+PGA-Arg 52.1 115-2 (22.8) 198.9 (54.3) V PS+ASP-Arg 50.5 120.4 (28.0) 201.1 (56.5) VI 2xPS+PGA-Arg 50.5 115.1 (22.7) 206.5 (61.8) Note : The daily feed intake is superimposable for all groups. Comments : Polymerized somatostatin (PS) is able to significantly increase growth with respect to control animals.

Claims: Claims ] . A derivative of somatostatin selected out of the following: d) a synthetic derivative of somatostatin 14 , having a Glu residue at the 4 position; a' ) a synthetic derivative of somatostatin 28, having a Glu residue at the 18 position; b) a synthetic derivative of somatostatin 14, having a Ser residue at the 6 position, at the 7 position, or at both said positions; b') a synthetic derivative of somatostatin 28, having a Ser residue at the 20 position, at the 21 position, or at both said positions, c) a carboxymethylation product of somatostatins with 14 or 28 amino acids; d) a polymerization product of somatostatin consisting of 14 or 28 am o acids; c) a conjugate of a somatostatin having l4 or 28 amino acids with at least a polyamino acid; f) a conjugate of a somatostatin having 14 or 28 amino acids with at least a fatty acid; g) a reductive alkylation product of an extractive somatostatin having 1 or 28 ammo acids; h) a amidmation product of a somatostatin having 14 or 28 amino acids; l ) a maleilation product of a somatostatin having 14 or 28 amino acids, ) a carbamylation product of a somatostatin having 14 or 28 ammo acids; k) a carbethoxylation product of a somatostatin having 14 or 28 amino acids ; 1) a nitration product of a somatostatin having 14 or 28 amino acids; m) a reaction product of a somatostatin having 14 or 28 amino acids with formaldehyde; n) a photooxidation product of a somatostatin having 14 or 28 ammo acids; o) a acetylation product of a somatostatin having 14 or 28 amino acids. 2. A derivative of somatostatin as claimed in claim 1, selected out of the derivatives of formula (I) S S I I ( I ) Ala-Gly-Cys-X-Asn-Y-Z-Trp-Lys-Thr-Phe-Thr-Ser-Cys 1 2 3 4 5 67 8 9 10 11 12 13 14 or the corresponding derivative of formula (I) wherein Asn is replaced with Asp, where: A) λ is Glu; Y is Phe and Z is Phe; B) X is Lys; Y is Ser and Z is Ser; C) X is Lys; Y is Phe and Z is Ser; D) X is Lys; Y is Ser and Z is Phe. . A derivative of somatostatin as claimed in claim 1, selected out of the derivatives of formula (II): ( II ) Ser-Ala-Asn-Ser-Asn-Pro-Ala-Met-Ala-Pro-Arg-Glu-Arg-Lys- l 2 3 4 5 6 7 8 9 10 11 12 13 14 S S I I -Ala-Gly-Cys-X- Asn-Y- Z -Trp-Lys-Thr-Phe-Thr-Ser-Cys 15 16 17 18 19 20 21 22 23 24 25 26 27 28 or the corresponding derivative of formula (II) wherein one or more Asn residues are replaced by Asp, where: A') X is Glu; Y is Phe and Z is Phe; B') X is Lys; Y is Ser and Z is Ser; C) X is Lys; Y is Phe and Z is Ser; D * ) X is Lys; Y is Ser and Z is Phe. 4. A derivative of somatostatin as claimed in any of claims 1 to 3 , selected out of the synthetic derivatives having 14 amino acids and derivatives of somatostatin having 14 amino acids. . A derivative of somatostatin as claimed in claim 1, wherein the product of polymerization of somatostatin having 14 or 28 ammo acids has a degree of polymerization ranging from 3 to 8 repeating units. 6. A derivative of somatostatin as claimed in claim 1, wherein the nitration product of somatostatin is obtained by treating somatostatin either with tetranitromethane or with 2-hydroxy-5-nι tro-benzyl bromide. 7- A derivative of somatostatin as claimed in claim 6, wherein the polyamino acid contains free -NH2 groups. 8 A derivative of somatostatin as claimed in claim 6, wherein the pohamino acid is poly-L-lysine having a molecular weight of 1,000 to 4,000 9 A derivative of somatostatin as claimed in claim 6, wherein the polvammo acid contains free -COOH groups. 10. A derivative of somatostatin as claimed in claim 6, wherein the polyamino acid is poly-L-glutamic acid having a molecular weight of 600, or poli-D, L-aspartic acid having molecular weight of 2000-10,000 Daltons. 11 A derivative of somatostatin as claimed in claim 1, wherein the conjugate of somatostatin with polyamino acid is obtained from a polvamino acid consisting of one or more free -SH groups 12 A derivative of somatostatin as claimed in claim 1, wherein the conjugate of somatostatin with a fatty acid is obtained from a fatty acid selected from the group consisting of palmitic acid, oleic acid, stearic acid and linoleic acid. 13. Process for the preparation of a derivative of synthetic somatostatin as defined in claim 1, including the total synthesis starting from the single ammo acids forming same, optionally the protected form. 14. Process for the preparation of a derivative of somatostatin, including the treatment of a somatostatin having 14 or 28 amino acids with glyoxylic acid, n the presence of cyanoboron hydride. 15 Process for the preparation of a derivative of somatostatin, including the polymerization of somatostatin in the presence of glutaraldehyde. 16. A process as claimed in claim 15, wherein somatostatin is treated in an aqueous medium, with glutaraldehyde, at a pH preferably ranging from 6.0 to 8.0, at a temperature ranging from 4°C to 4θ°C. 17- A process as claimed in claim l . wherein the pH is 6.7-6.9 and the temperature is room temperature (20°C to 25°C). l8 A process as claimed in claim 15, wherein glutaraldehyde is used in a quantity corresponding to 10 -4 to 10-< J =; mol glutaraldeyde every lO-- 5 /'10~ -NH2 groups of somatostatin and, at the reaction end, glutaraldehyde excess is neutralized by treatment with lysme, under the same conditions as adopted for the polymerization. 19- Process for the preparation of a somatostatin derivative including the treatment of a somatostatin having 14 or 28 amino acids with at least a polyamino acid containing free -NH groups, m the presence of glutaraldehyde. 20. A process as claimed in claim 19, wherein said treatment is carried out in an aqeuous medium, at a pH ranging from 6.0 to 8.0 and at a temperature ranging from 4°C to 4θ°C. 21. A process as claimed in claim 19, wherein the pH ranges from 6.7 to 6.9 and the temperature is room temperature (20°C to 25°C) . 22. A process as claimed in claim 19, wherein glutaraldehyde is used a quantity corresponding to 10 -4 to 10- J mol glutaraldeyde every 10 ~n /10 ~ -NH2 groups of the polyamino ac d and, at the reaction end, glutaraldehyde excess s neutralized by treatment with lysine, under the same conditions as adopted for the conjugation. 23. Process for the preparation of a derivative of somatostatins, including the treatment of a somatostatin having 14 or 28 ammo acids with at least a polyamino acid containing one or more free -COOH groups or with at least a fatty acid, in the presence of a carbodiimide. 24. A process as claimed in claim 23, wherein said treatment is carried out in an aqueous medium, at a pH ranging from to 6 and at a temperature ranging from 30°C to 4θ°C. 25. A process as claimed in claim 23, including the treatment of the polyamino acid containing free -COOH (or the fatty acid) with a carbodiimide, in a stoichiometric excess in respect of the -COOH groups, in an aqueous medium, at an alkaline pH, at a temperature ranging from 10°C to 4θ°C, e.g. 37°C, followed by the treatment of the resulting product with somatostatin, in an aqueous medium, at a pH ranging from to 6, at a temperature ranging from 30°C to kO "C . 26. A process as claimed in claim 25, wherein the pH ranging from 5 to 6 is 5-5. the alkaline pH is 8 to 10, and the temperature is 37 °C. 2 ~ J . Pt process as claimed in any of claims 23 to 26, wherein the carbodiimide is N-ethyl-N' (dimethylammopropyl) carbodiimide. 28. Process for the preparation of a derivative of somatostatins. including the treatment of a somatostatin consisting of 14 or 28 am o acids with at least a polyamino acid containing one or more free -SH groups, in the presence of a dithiobifunctional reagent. 2 • A process as claimed in claim 28, wherein said dithiobifunctional reagent is N-succιn myl-3- (2-pyπdyl-dιthιo)propιonate. 30. A process as claimed in any of claims 19 to 29, wherein the somatostatms/polyamino acids molar ratios range from 1.2 to 1:5- 31- process as claimed in any of claims 23 to 27, wherein the somatostatms/fatty acids molar ratios range from 1:2 to 1:5- 32. Process for the preparation of a somatostatin derivative, including the treatment of a somatostatin having 14 to 28 ammo acids with tetranitromethane. 33 A derivative of somatostatin that may be obtained according to one of the processes claimed in any of claims 14 to 32. 3^- Pharmaceutical composition containing at least a somatostatin derivative as claimed in any of claims 1 to 12, combined with one of more pharmaceutically acceptable excipients or diluents or mixtures thereof. 35- A pharmaceutical composition as claimed in claim 3^ m the form of a preparation for injection. 3 . A pharmaceutical composition as claimed in claim 35 being of the sustained release type. 37- Use of derivatives of somatostatins as claimed m any of claims 1 to 12 or in claim 33 for the preparation of pharmaceutical compositions useful to promote body growth and development in man and animals. 38. The use as claimed in claim 37, wherein said compositions are useful in the treatment of pathologies associated with delayed or reduced body development in man and animals . 39 • The use as claimed in claim 37. wherein said compositions are useful to accelerate livestock growth cycles. 40. The use as claimed in claim 37. wherein said somatostatin derivatives are to be administered by the parenteral way. 4l. The use of a compound selected out of L-ammo acids, oligopeptides other than somatostatin derivatives containing at least a D, L or D,L pyroglutamic acid residue or at least one D, L or D,L- aspartic acid residue and at least an L-amino acid residue, oligopeptides other than somatostatin derivatives containing at least a basic L-amino acid residue, and salts thereof with pharmaceutically acceptable acids or bases, for the preparation of a pharmaceutical or dietary composition useful to promote body growth in combination with somatostatin derivatives as claimed in claims 1-12. 42. The use as claimed n claim 41, wherein the compound is L-arginine or L-lysine. . The use as claimed in claim 4l, wherein the compound is L- arginine, salified with D,L-pyroglutamιc acid or with D,L-aspartιc acid. 44. The use as claimed in claim 41, wherein the compound is an oligopeptide selected from the group consisting of dipeptides, tripeptides and tetrapeptides . The use as claimed m claim 4l, wherein the oligopeptide contains one or more residues of L-argmine, L-lysine or mixtures thereof. 46 The use as claimed in claim 4l, wherein the oligopeptide contains only one D, L or D,L pyroglutamic acid residue or D, L or D,L aspartic acid situated at the beginning of the ammo acidic sequence. 47. The use as claimed in claim 41, wherein the oligopeptide is selected out of the following compounds: D,L-Pyr-Arg-Arg D,L-Pyr-Arg-Arg-Arg where D,L-Pyr is D,L-pyroglutamιc acid; Lys-Arg-Arg and D.L-Asp-Arg, wherein D,L-Asp is D,L-aspartιc acid. 48 Oligopeptide containing at least a D, L or D,L pyroglutamic acid o D, L or D,L aspartic acid residue and at least an L-ammo acid residue. . Oligopeptide selected out of: D,L-Pyr-Arg-Arg D.L-Pyr-Arg-Arg-Arg D.L-Asp-Arg. 50 • Pharmaceutical or dietary composition containing a compound selected out of L-ammo acids, oligopeptides other than somatostatin derivatives containing at least a pyroglutamic acid residue or at least an aspartic acid residue and at least an L-am o acid residue, oligopeptides other than somatostatin derivatives containing at least a basic L-ammo acid residue other than somatostatin derivatives, and salts thereof with pharmaceutically acceptable acids or bases, in combination with one or more pharmaceutically acceptable excipients, as defined in anyone or claims from 4l to 49- 51 A kit comprising a somatostatin derivative as defined in anyone of claims 1-12 or 33~36 and at least a compound as defined in claims 4l to 49- 52. A kit according to claim 1. wherein said compound is formulated as dietary composition. A kit according to claim 52, wherein the dietary composition is a concentrated supplement for mixing or blending with animal feed. ^( • A therapeutic method for promoting body growth and development in men and animals, comprising administering to a subject in need of such treatment an effective amount of a somatostatin derivative according to claims 1-12. 55 A therapeutic method according " to claim 5^ . comprising administering said somatostatin derivative in association with a compound as defined in claim 1-12.

Inventors: BIZZINI BERNARD, GRABITZ ERNST BERNHARD, VOLPATO IVO, BIZZINI, BERNARD, GRABITZ, ERNST, BERNHARD, VOLPATO, IVO
Applicants: BIZZINI BERNARD, DOX AL ITALIA SPA, GRABITZ ERNST BERNHARD, VOLPATO IVO, BIZZINI, BERNARD, DOX-AL ITALIA S.P.A., GRABITZ, ERNST, BERNHARD, VOLPATO, IVO
Application year: 1997
Main classification: C07K14
IPC codes: A61K38, C07K5, C07K14