Biomedical subjects
Publications and source records attributed to D Hock.
Colon cancer is the second most common cause of cancer death and the first one in non-smoking persons. None of the current colorectal caner screening options is ideal. As for mammography in breast cancer screening, virtual colonoscopy, although still in clinical evaluation, promises to become a primary screening method as it is performant, quick, non-invasive and cheaper than conventional colonoscopy.
In our institution, MRCP is actually replacing diagnostic ERCP. This study is addressing its accuracy in the diagnosis of symptomatic choledocholithiasis. 137 MRCP were performed in patients with upper abdominal pain and biological anomalies (n = 48), pain with cholelithiasis at sonography (n = 69) or non-alcoholic acute pancreatitis (n = 20) on a 1.5 T system with high gradients using a standardized combination of breath-hold HASTE and RARE sequences. We included in our study 74 patients who underwent as second test ERCP (n = 36), peroperative cholangiography (n = 13), or extensive follow-up with laboratory tests and/or sonography (n = 25). All examinations were judged as diagnostic, discrepancies between direct cholangiography and MRCP being noted in 4 patients (5.4%). Lithiasis was misinterpreted on MRCP as bubbles in 2 patients after sphincterotomy or surgery. We had two false positive diagnoses on MRCP: in one patient peroperative cholangiography was negative and in the other one ERCP was negative. With a sensitivity and PPV of 92%, a specificity and NPV of 96% MRCP in our experience is shown as an accurate diagnostic tool for the detection of stone in the common bile duct replacing ERCP.
Ultrasonography and CT-scanner remain the first choice nowadays concerning detection and preoperative work-up of pancreatic cancer. MRI offers interesting options for the detection of liver metastases, and high quality of ductal and vascular examination. Actually, while we await a larger diffusion of MR systems and radiological expertise this technique is preferentially indicated as a third-step procedure when ultrasonography and CT-scanner are normal despite a real suspicion. Otherwise, MRI permits with a single non-invasive examination a complete work-up useful to prepare palliative therapy in case of unresectable tumor.
Advances in the treatment of clinical disorders of mineral in homeostatis and metabolic bone disease with intact parathyroid hormone 1-84 or one of the biologically active N-terminal fragments require a precise and sensitive measurement in serum. Therefore, a two-site immunoenzymometric assay for the quantitative determination of bioactive hPTH-1-37 (human parathyroid hormone) at picomolar concentrations was developed. Monoclonal antibodies (mAB) against hPTH-1-37 were raised by hybridoma cells in serum-free cell culture. Furthermore, sequence-specific polyclonal antibodies were obtained by immunisation of rabbits using multiple antigenic peptides (MAP) representing the conspicuous regions of the primary structure of hPTH-1-37. The polyclonal and monoclonal antibodies were characterised by epitope mapping. The combination of a monoclonal antibody (13C63/5) recognising hPTH fragment 16-24 with a polyclonal antibody (k2) showing a predominant binding sequence at hPTH-1-5 led to a sandwich assay specific for N-terminally intact and therefore biologically active hPTH. The validated assay ranging from 4 to 1000 pmol/l was applied to pharmacokinetic studies of hPTH-1-37. After s.c. administration of 30 mu g/kg in 5 beagles, the maximum serum concentrations of hPTH-1-37 ranging at 2139 +/- 857 pmol/l were observed 45 min after the injection. Clearance of the peptide calculated from the exponential disappearance curve was 32.0 +/- 9.1 ml/min/kg with a mean t1/2 of 37 +/- 10 min.
To generate site-specific antibodies to the N-terminal bioactive fragment of the parathyroid hormone hPTH 1-37, multiple antigenic peptide systems (MAP) for immunization were used. Two 10 residue fragments and a 14 residue fragment derived from knowledge of the secondary structure of hPTH 1-37 were selected to be synthesized as MAPs. Each peptide (hPTH 1-10, hPTH 9-18, and hPTH 24-37) was synthesized directly onto a branching heptalysine core matrix by automated solid phase synthesis. The hPTH 1-10 and the hPTH 24-37 MAP were highly immunogenic in rabbits. Ten polyclonal antisera obtained from rabbits were characterized by epitope mapping. Antigenic determinants were found as follows: 1) Sera K1-K3 raised to MAP 1-10 showed a predominant binding sequence at hPTH 1-5. 2) Sera K4-K6 raised to MAP 8-18 preferentially bound to residues 9-14. 3) Immunizing with hPTH 24-37 MAP led to antisera characterized as follows: serum K7 recognized residues 24-37, the sequence used for immunization, sera K8, K9 and K10 bound to residues 24-37 and 26-34. In summary, the favoured regions as deduced from the secondary structure of hPTH 1-37 were covered by the produced antibodies.
The occurrence of hPTH-1-37 as the native bioactive circulating form of PTH-1-84 has now been obtained using a specific purification procedure for circulating parathyroid hormone, which involves a newly developed immunoenzymetric assay for N-terminally intact hPTH. In combination with two different methods of mass spectrometry, the molecular weight of the isolated immunoreactive peptide was shown to be 4401 Da, which corresponds to hPTH-1-37. Synthetic hPTH-1-37 material was tested in the chick bioassay and produced a clearcut increase in serum calcium concentration. We conclude that hPTH-1-37 is the native bioactive fragment of hPTH-1-84 in circulation.
The aim of this study was to explore whether sodium chloride is involved in the release of urodilatin from epithelial human embryonic kidney cells (HEK-293). Using a highly specific urodilatin radioimmunoassay combined with HPLC, gel chromatography, and a cyclic GMP generating bioassay, we demonstrate that HEK-293 cells release a biologically active 3.5 kD, urodilatin-like immunoreactive substance. To show the effect of sodium on urodilatin release, HEK-293 cells were incubated with cell culture buffer containing 120, 130, 140, and 150 mmol/l sodium, respectively. Urodilatin secretion from HEK-293 cells is increased to 176% when extracellular sodium is raised to 150 mmol/l (control: 120 mmol/l = 100%). There was no significant difference when exposing the cells to 140 mmol/l or 150 mmol/l sodium. It is suggested, that beside the known extrarenal factors influencing urodilatin secretion, high cephalic sodium and cardiac volume load, urodilatin secretion might also be regulated by an intrarenal sodium sensitive mechanism.
The aim of our study was to investigate whether urodilation (URO, INN: ularitide) is present in rat urine and if URO excretion in the rat is influenced by dietary sodium intake. Therefore, three groups of Wistar rats were placed in metabolic cages where they received different sodium diets for 9 days (0.05%, 0.4%, and 8.0% NaCl, respectively). Food and water intake were determined by weight. At days -4, 2, 5, and 8 blood pressure was measured non invasively using the tail cuff method. After nine days rats were anesthetized and blood was drawn for serum electrolyte, plasma A-type natriuretic peptide (CDD/ANP-99-126), and plasma aldosterone concentration measurements. Using a highly specific antibody against URO combined with high performance liquid chromatography and gel chromatography, we were able to show that a URO-like substance of approx. 3.5 kD that is distinct from CDD/ANP-99-126, brain natriuretic peptide, and C-type natriuretic peptide, is present in rat urine. Sodium chloride loaded rats showed significantly increased urinary excretion rates of URO (p < 0.001), chloride (p < 0.001), sodium (p < 0.001), and the fractional excretion of sodium (p < 0.001). In the plasma, sodium (p < 0.01) and chloride (p < 0.001) increased, while potassium, hematocrit, osmolality, plasma CDD/ANP-99-126, as well as glomerular filtration rate (GFR), and systolic blood pressure did not change. Since CDD/ANP-99-126 is believed to be a natriuretic peptide, it is suggested that CDD/ANP-99-126 might participate in the natriuresis due to high dietary sodium intake. In sodium-loaded rats, however, plasma CDD/ANP-99-126 remains unchanged, while URO excretion increases with sodium excretion, independent of GFR and blood pressure. We conclude that URO secretion is stimulated by dietary salt loading and might be involved in the regulation of water and electrolyte metabolism in the rat.
The purpose of this study was to assess the possibility of isolating biologically active peptides from human blood using large volumes of blood filtrate, which are available from patients undergoing extracorporeal ultrafiltration because of renal insufficiency. This filtrate was submitted to six chromatographic separation steps, yielding one purified peptide which was completely analysed in its primary structure. It was found to be strikingly similar to proteins, described initially as rabbit uteroglobin (or blastokinin) and, more recently, from human bronchial lavage as the '10 kDa Clare cell protein', as well as from human urine as 'protein-1'. The natural molecule contains two chains of identical amino acid sequences of 70 residues which are arranged as an antiparallel dimer due to the disulphide bonds between two cysteines at positions 3 and 69. Mass analysis of the molecular forms yielded molecular weights from 15827 Da (non-oxidized form) to 15859 Da (bi-oxidized form). We conclude that this peptide isolated from the filtrate represents the human uteroglobin, and we demonstrate for the first time that this peptide may be involved as a humoral factor in reproductive or other physiological functions.
PURPOSE: To assess, in one single procedure, a complete study of the female pelvis, including the Douglas pouch. METHODS: Colpocystodefecography (CCD) combines vaginal opacification, voiding cystography, and defecography. Three hundred examinations are reviewed. RESULTS: Thanks to the simultaneous visualization of the pelvic structures, CCD proved to be more useful than clinical evaluation to diagnose prolapses and particularly Douglas pouch hernias (enteroceles), the clinical diagnosis of which was missed in 93 of 111 cases. Moreover, in addition to morphologic and functional information, CCD brings about a new insight in the study of pelvic organs reciprocal influences, should they be positive (supporting function) or negative (external compression). Finally, significative pelvic surgery and particularly hysterectomy enhances greatly the risk of enteroceles. CONCLUSION: CCD is helpful in the preoperative staging, especially in the selection of the surgical procedure that will least likely predispose to possible late postoperative complications such as vaginal prolapses or enteroceles.
Porcine brain natriuretic peptide of 26 amino acid residues (pBNP-26) is inactivated by endoprotease-24.11 (EC 3.4.24.11) of kidney cortical membranes. In contrast to human alpha atrial natriuretic peptide/cardiodilatin (ANP/CDD) showing a single major cleavage within the disulfide-linked loop between Cys and Phe in position 7 and 8, pBNP-26 is cleaved at several sites. Although both pBNP-26 and ANP/CDD exhibit Cys-Phe peptide bonds at the corresponding positions this bond is not cleaved in BNP-26.
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This review indicates that the heart is a polypeptide-producing organ which should be classified among the traditional endocrine tissues. Cardiac hormones have only been known for a few years, the discovery of their endocrine functions, however, occurred in the 1950ies when Gauer, Henry and Kisch observed specific physiological and morphological features of the heart atria indicative of an endocrine activity. Because of their basic effects many target organs involved in the regulation of body fluid pressure and composition are related to this endocrine organ located in the atrial appendages of the heart. The compact endocrine portion of the heart is built up by myoendocrine cells which form the functional endocrine units and produce a variety of polypeptide hormones called cardiodilatin (CDD) or atrial natriuretic polypeptide (ANP), which belong to one family. Also, co-storage of a partially homologous regulatory polypeptide called brain natriuretic polypeptide (BNP) occurs, as has been determined by immunohistochemistry and radioimmunoassay. CDD and/or BNP are found in numerous organs where they exert paracrine and neurocrine functions, e.g., in the brain, peripheral nervous system, kidney, and adrenal medulla. In these organs, a differential post-translational processing of cardiac polypeptides is observed, resulting in different functional activities according to discriminating receptor interactions and degrading metabolism. Some of the extra-auricular sites of synthesis and storage of CDD-like peptides are briefly mentioned. In summary the heart constitutes the center of a multilocal and multifunctional system of specific cardiac polypeptides of endocrine, paraneuronal, and neuronal character.
Two major forms of cardiac peptides have been established in the last few years: (a) a prohormone of 126 amino acids (CDD/ANP-1-126) in the endocrine heart and (b) the circulating CDD/ANP-99-126 (= alpha ANP) in blood plasma. The method we applied earlier to isolate the circulating form of cardiodilatin from human blood was used to detect and analyze the biologically active, predominant form of the same polypeptide family excreted by the kidneys. Each step of the isolation procedure was followed up by a bioassay using an in vitro vascular smooth muscle relaxation test and a highly specific RIA against cardiodilatin (CDD-99-126) for the initial purification steps. The polypeptides excreted in 1000 l of normal human urine were adsorbed to 2.5 kg of alginic acid, and after elution and lyophilization processed on a G-25 Sephadex column. The obtained crude polypeptide fractions were applied to ion-exchange chromatography. Thereafter four steps of HPLC were carried out to purify the polypeptide which was the suggested form of cardiodilatin (CDD) in human urine. The amino acid analysis and gas phase sequence analysis showed that the main form of urinary cardiodilatin is a 32 amino acid residue containing molecule, cardiodilatin-95-126. The molecule is N-terminally extended compared to the circulating CDD-99-126. This suggests that the analyzed urinary peptide is not the residual plasma form, filtrated and renally cleared from blood, but probably a polypeptide produced and processed in the kidney tubules and cleaved by a different postranslational process. Therefore, this vasorelaxant polypeptide is called urodilatin.
Atrial natriuretic peptide (CDD/ANP-99-126) is rapidly inactivated by a membrane preparations from dog kidney cortex. Inactivation occurs by cleavage of the ring structure in the position between Cys-105 and Phe-106. A unique proteolytic product separated by HPLC on reverse-phase column appears as a single peak which elutes prior the intact peptide. In contrast, CDD/ANP-95-126 (urodilatin) which is released from the kidney is not destroyed by proteolysis using an identical membrane preparation.
Cardiodilatins/atrial natriuretic peptides (CDD/ANP) exhibit a common amino acid sequence: Arg101-Arg102-Ser103-Ser104. Cyclic AMP-dependent phosphorylation of Ser104 of atrial peptides with [gamma-32P]ATP enables rapid identification of cardiac hormones. The biological activity of in vitro phosphorylated cardiodilatin (CDD-28/alpha-hANP) is dramatically altered compared to the unphosphorylated peptide: the vaso-relaxant effect of cardiodilatin 28 is inhibited upon phosphorylation.
Cardiodilatin (CDD), a polypeptide exhibiting vasorelaxant and diuretic natriuretic bioactivity, was isolated from bovine atria. The isolation procedure reported here is different from that originally used for the purification of porcine and bovine CDD. Instead of cation-exchange chromatography on Fractogel TSK-CM 650 S and several purification steps on different high-performance liquid chromatographic (HPLC) columns, it is now possible to obtain CDD-88 by an automated fast-protein liquid chromatography system for repeated injections and a motor valve as fraction collector and only one final step of reversed-phase HPLC on a TSK-ODS-120T column.
Glaser Safety Slug TM ammunition is a uniquely designed, essentially prefragmented ammunition. Tests performed by the U.S. Justice Department demonstrated that the ammunition possesses high kinetic energy, high relative incapacitation index (RII) and poses a very low risk to bystanders because of its total loss of kinetic energy in the target. Despite having been manufactured since 1974, no deaths from this ammunition have been previously reported. The authors herein describe the first three reported human deaths.