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Biomedical subjects

R Scharf

Publications and source records attributed to R Scharf.

At least 55 records · Page 3Linked to original sources
PubMed1987

Evaluation of early postsplenectomy complications.

This study was done to define the incidence of early postsplenectomy complications and is based upon 688 splenectomies--mainly in malignant and nonmalignant hematologic conditions--performed during the period 1952 to 1986. In 354 patients, early postoperative complications were observed, among whom wound and pulmonary infections were most common. A fatal outcome was noted in 32 patients for a mortality rate of 4.7 per cent. The incidence of early complications after splenectomy is higher than after most other surgical procedures within the abdominal cavity and depends upon the underlying diseases which lead to splenectomy. Deficient immunologic defense mechanisms may be a significant factor in the development of early complications in patients after splenectomy.

Adolescent↗
PubMed1986

[Hemodynamic studies of iloprost-conditioned ischemically stressed kidneys in animal experiments].

By means of computer-assisted Doppler signal analysis on the exposed renal artery of the pig the change of the haemodynamics under the influence of Iloprost is investigated in comparison to the electromagnetic flow measurement. The Doppler sonographic establishment of the speed of the blood flow and the relative volume of the blood flow allows additional informations about characteristic changes of the form of the pulse. During the measurement in situ on the renal artery the result was during the intraarterial application of Iloprost a distinct increase of the renal blood flow with simultaneous decrease of the renal resistance, which, issuing from the Doppler signal analysis, is characterized as change of the renal resistance index. The kidneys conditioned under influence of Iloprost were retransplanted after a warm ischaemia-time of 45 minutes with following machine preservation of 24 hours and showed a stable flow characteristics for the whole investigation period. The Doppler signals directly conducted via the renal parenchyma showed a stable pulsation also in the smaller arterial vessels.

Animals↗
PubMed1983

Synthesis of the porcine intestinal peptide PHI and its 24-glutamine analogue.

PHI--a new candidate hormone from porcine intestinal tract-- corresponds to a linear heptacosapeptide amide of remarkable sequence homology to the known members of the glucagon family, particularly to the vasoactive intestinal peptide (VIP) and secretin. The position 24 usually occupied by an aminodicarboxylic acid omega-amide, in the present case, however, carries a glutamic acid, thus opening the question of whether this structural feature is related to desamidation in one of the isolation and characterization steps or of whether it is significant for this peptide factor. Consequently the heptacosapeptide amides corresponding to the proposed primary structure and to its 24-glutamine analogue have been synthesized. Comparative chromatographic and biological studies on the natural and the two synthetic products have confirmed the correctness of the primary structure proposed for the isolated PHI. Since [24-glutamic acid] and [24-glutamine]PHI exhibit no significant differences in their biological potencies, the main question is still open of whether the position 24 in native PHI is occupied by the aminodicarboxylic acid omega-amide (glutamine) or by N-substituted derivatives (N-glycosyl).

Amino Acid Sequence↗
PubMed1983

[Syntheses of human little gastrin-I and its leucine-15, norleucine-15 and methoxinine-15 analogs].

Human little gastrin-I is known to exhibit a high tendency to air-oxidation of its methionine-15 residue to the corresponding S-oxide derivative, with concomitant loss of biological activity. Since its leucine-15 analog, even if fully biologically active, differs significantly from the parent hormone in the immunological properties, the norleucine-15 and methoxinine-15 analogues were synthetized. For the required comparative analyses new syntheses of human little gastrin-I and of its leucine-15 analog were additionally elaborated. Upon an optimized condensation of the fragments, followed by the deprotection step, partition chromatography as well as preparative high-performance liquid chromatography led to the desired gastrins in satisfactory yields and high degree of purity as judged by the expected and known side products.

Amino Acid Sequence↗
PubMed1982

[Ultrasonic Doppler methods of blood flow studies of the arterial circulation from the aorta up to the kidney parenchyma in animals].

The Doppler method of ultrasonography was used in experimental investigations to examine the circulator behaviour at various points in the arterial system in the retroperitoneum as fast as the kidney in animals with normal circulation. This enabled reproducible Doppler curves to be determined. It remains to be seen to what extent characteristic curve patterns exist for e.g. partial or subtotal vascular occlusion. For the future it will be especially important to determine the flow curves in the cortical region of the renal parenchyma as an area of small and very small vessels, for this can give us important information on the circulation of blood in the individual segments of the kidney.

Animals↗
PubMed1981

[Total synthesis of somatostatin-28 (author's transl)].

The total synthesis of the octacosapeptide corresponding to the proposed primary structure of porcine somatostatin-28 is described. The synthesis has been performed using a protection scheme of maximum selectivity (acid labile side chain protection based on tert-butyl alcohol and 1-adamantol derived protecting groups in combination with the S-tert-butylthio group for reversible and selective blocking of the cysteine thiol functions and the 2-nitrophenylthio group for the temporary protection of the alpha-amino functions of intermediate segments) and of carefully selected fragments. Upon assembly in sequence order of the four suitably protected fragments related to sequences 18-28, 15-17, 8-14 and 1-7, the asymmetric disulfides were reduced by exposure of the fully protected octacosapeptide to phosphines. Subsequently, the final deprotection was performed with trifluoroacetic acid and the resulting dihydrosomatostatin-28 was then converted by air oxidation into the "cyclic peptide". Gel filtration on Biogel P-6 and ion-exchange chromatography on Biogel CM-2 produced somatostatin-28 at a high degree of purity. Comparative analysis of the synthetic and natural product by means of chromatographic, immunological and biological assays confirmed the structure proposed for this putative precursor of somatostatin-14.

Amino Acid Sequence↗
PubMed1981

[Total synthesis of human big gastrin I. Revised primary structure (author's transl)].

The synthesis of the tetratriacontapeptide amide corresponding to the revised structure of human big gastrin I is described. The fully protected peptide derivative was obtained by assembly in sequence order of the suitably protected fragments [1--9], [10--14] and [15--34] via the dicyclohexylcarbodiimide/N-hydroxysuccinimide and azide method, respectively. Upon removal of the protecting groups by exposure to trifluoroacetic acid and purification of the resulting crude product by chromatographic methods, human big gastrin I was obtained in satisfactory yields and at a high degree of purity. The identical immunological crossreactivities of natural and synthetic human big gastrin I using anti-porcine big gastrin I antiserum strongly supports the correctness of the newly proposed primary structure of this member of the gastrin family.

Amino Acid Sequence↗
PubMed1981

[Studies on the total synthesis of cholecystokinin-pancreozymin. Synthesis of the suitably protected fragment corresponding to the sequence 24--33 (author's transl)].

The synthesis is described of a suitably protected decapeptide derivative corresponding to the C-terminal tyrosin-O-sulfate-containing sequence 24--33 of cholecystokinin-pancreozymin as key fragment for the total synthesis of this gastrointestinal hormone or its 39-variant. This peptide derivative has been prepared according to our newly developed procedure based on the direct use of N-acyltyrosine-O-sulfate barium salt. Additionally, removal of the protecting groups followed by purification via chromatographic methods produced the decapeptide amide in good yields and with a high degree of purity as a fully active cholecystokinin-pancreozymin related peptide.

Cholecystokinin↗