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D Hock

Publications and source records attributed to D Hock.

32 records · Page 2Linked to original sources
PubMed1986

Isolation and structural analysis of the circulating human cardiodilatin (alpha ANP).

A new method was applied to isolate a polypeptide hormone from human blood. The polypeptides from 1,000 1 of hemofiltrate with a molecular weight lower than 20 kDaltons were adsorbed to 2.5 kg alginic acid, then eluted, precipitated, and desalted on a G-25 Sephadex column, thus obtaining a crude lyophilised plasma polypeptide extract. These polypeptides were further submitted to ion-exchange chromatography. Thereafter, two steps of HPLC were carried out to purify a distinct polypeptide which was the circulating form of cardiodilatin (CDD) in this case. The amino acid analysis, C-terminal enzymatic cleavage by carboxypeptidase A, and sequence analysis showed that the only form of circulating cardiodilatin is the 28 amino acid residue containing molecule, cardiodilatin-99-126 cleaved from the C-terminus of cardiodilatin-126 and identical with alpha-ANP (alpha atrial natriuretic polypeptide). Other bioactive molecular forms of the polypeptide hormones of the cardiodilatin family were not detected in the hemofiltrate. The isolation procedure was followed up by a bioassay using in vitro vascular smooth muscle relaxation.

Amino Acid Sequence↗
PubMed1986

Cardiac hormones: morphology and biochemistry.

The heart contains, in addition to its myocardial working cells and the conductive system, a specialized endocrine part localized mainly in the atrial appendage which is predominantly made up by myoendocrine cells. The ultrastructural and immunocytochemical analysis of myoendocrine cells show a specialized secretory apparatus involved in the synthesis and secretion of cardiac hormones. These cardiac hormones are synthesized and processed in the myoendocrine cells as follows: a preprohormone is found in the rough endoplasmic reticulum, the prohormone cardiodilatin/gamma-atrial natriuretic polypeptide (CDD/ANP) is processed in the Golgi apparatus and stored in the secretory granules. The circulating peptide, cardiodilatin 99-126/alpha-ANP, is the C-terminus of this preprohormone which is released as the active circulating form into the blood stream.

Animals↗
PubMed1984

The auricular myocardiocytes of the heart constitute an endocrine organ. Characterization of a porcine cardiac peptide hormone, cardiodilatin-126.

A peptide hormone was extracted from the porcine right atrium following a bioassay for differential vasorelaxant effects on smooth muscle strips from aorta and renal and inferior mesenteric arteries. The isolation procedure included several steps of gel-permeation and ion-exchange chromatography, and high performance liquid chromatography. During the isolation procedure, other peptides of smaller molecular weight were also found, which, in relation to cardiodilatin-126 (CDD-126), are shorter at their N-terminal. Among these, CDD-88 has also been isolated and characterized, and has been established as a prominent member of the cardiac hormone family. The N-terminal and C-terminal segments of the 126 amino acid-containing molecule were synthesized and used to raise region-specific antibodies. The natural peptide was then localized within myoendocrine cells of the right atrium where specific atrial granules are located. Renal effects of cardiodilation were studied in conscious dogs and showed strong diuretic and natriuretic activities. According to our functional studies, cardiodilatin-126 and cardiodilatin-88 possess qualities of a significant hormone family regarding the regulation of extracellular fluid volume and blood pressure.

Amino Acid Sequence↗
PubMed1983

The right auricle of the heart is an endocrine organ. Cardiodilatin as a peptide hormone candidate.

A new polypeptide hormone candidate regulating vascular smooth muscle function was extracted from porcine atrial tissue. The purification steps were followed by a bioassay. The hormonally active substance has been analyzed and found to be a small polypeptide exhibiting a molecular weight of about 7500 and is named "cardiodilatin" (CDD). Further chemical data on this new hormone will be published elsewhere. A partial amino acid sequence of cardiodilatin is offered and shows that among the well known hormones or neuropeptides, none exhibit a homologue partial sequence.

Amino Acid Sequence↗
PubMed1981

A new hypothalamic substance, and not luteinizing hormone-releasing hormone, is detected immunocytochemically by antibody to luteinizing hormone-releasing hormone.

Adjacent paraffin sections of rat hypothalami fixed in Bouin's fluid were treated either with buffer or with luteinizing hormone-releasing hormone (LHRH) before immunocytochemical staining with anti-LHRH. Upon buffer pretreatment, pituitary gonadotrophs were unstained and hypothalamic fibers were stained. Upon LHRH pretreatment, pituitary gonadotrophs were stained (receptor reaction) and hypothalamic fibers were unstained. Extension of washes and use of series of neutralizing antisera between LHRH application and immunocytochemical staining, as well as the absence of inhibiting concentrations of LHRH in the later washes and neutralizing antisera removed from the sections, excluded the possibility that the disappearance of visualization of hypothalamic fibers was due to blockage of anti-LHRH in immunocytochemical staining. The results suggested that LHRH removed from the sections an immunocytochemically stainable but as yet unknown analog of LHRH and replaced it with LHRH, which in turn became lost during subsequent immunocytochemical processing. This idea was confirmed by the isolation by high-pressure liquid chromatography of a peak, distinct from LHRH, upon treatment of hypothalami with LHRH. It is suggested that the new substance may be carrier-held and that this substance, rather than LHRH, is normally detected by immunocytochemistry with anti-LHRH. Added LHRH binds not only to high-affinity pituitary receptors but also to low-affinity hypothalamic carriers.

Animals↗
PubMed1977

Flow microfluorometric monitoring of the interaction of lipid vesicles with cells.

Flow microfluorometric techniques have been applied to experiments concerned with the penetration of cells by lipid vesicles. The high sensitivity of laser flow systems enables to measure the weak fluorescence emitted by individiual liposomes tagged with perylene, inserted into their multilamellar layer. The total fluorescence of cells which habe incorporated such perylene-loaded liposomes could be measured and well separated from that unbound liposomes. Significant differences in the incorporation rates of cationic and anionic liposomes were shown by means of time-course analyses of cellular fluorescence spectra. The advantages of the rapid data analysis by flow fluorescence techniques is discussed in comparison with conventional radio-isotopic methods.

Computers↗
PubMedDate not supplied

[Defecation disorders. Characteristics of manometric studies and rehabilitation].

The authors review the literature and their personal experience about the systematic exploration of defecation disorders by anorectal manometry and colpocystodefecography. They stress the importance of combining functional and morphological evaluation, in order to avoid inappropriate surgery. Concerning anorectal manometry, the determination of the smallest volume of rectal distention inducing a complete relaxation of the internal anal sphincter was found more useful than the maximal tolerable volume in the exploration of defecation disorders. Finally, the authors report the results of biofeedback conditioning prescribed in 30 patients (27 women, 3 men, mean age: 55 years) with defecation disorders (terminal constipation in 21, fecal incontinence in 9 patients). Several characteristics of anorectal manometry and of defecography were significantly improved after biofeedback conditioning.

Adult↗