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W Debinski

Publications and source records attributed to W Debinski.

69 records · Page 4Linked to original sources
PubMed1986

Improved liquid chromatographic determination of dopamine-beta-hydroxylase activity in tissues and plasma.

We describe a new assay for dopamine-beta-hydroxylase (D beta H) activity in human and rat plasma and rat tissues using reversed-phase high-performance liquid chromatography with electrochemical detection. Human and rat plasma D beta H activity was measured directly, without extraction of the enzyme. The D beta H from rat tissues was extracted on Concanavalin A-Sepharose before the assay to avoid interference from the presence of tissue catecholamines. Dopamine, the natural substrate of D beta H, was utilized at optimal (enzyme-saturating) concentration. The reaction product, norepinephrine, was isolated on Dowex AG 50W-X4 (H+ form) column. An internal standard, [3H]norepinephrine, was included to correct for the loss of norepinephrine during the procedure. This method allows for the first time the determination of D beta H activity in small volumes of rat and human plasma (5-20 microliters) and tissues. The procedure can be easily set up in any laboratory equipped with a high-performance liquid chromatograph, an electrochemical detector, and a liquid scintillation counter.

Animals↗
PubMed1986

ANF-like peptide(s) in the peripheral autonomic nervous system.

The recent demonstration of the atrial natriuretic factor (ANF) within the brain has been extended in the present study by the additional localization of ANF-like activity in the peripheral nervous structures. Using a sensitive radioimmunoassay, it was possible to detect ANF-like immunoreactive peptide(s) in crude and chromatographically separated extracts of parasympathetic rat ganglia. The partially purified ANF-like peptide exhibited a biological action similar to cardiac ANF. This finding supports a possible involvement of ANF in the regulation of both, central and peripheral neuronal activities.

Adrenal Cortex↗
PubMed1986

Zona glomerulosa cell responses to atrial natriuretic factor in genetically hypertensive rats.

We examined whether abnormalities in target cell responsiveness to atrial natriuretic factor (ANF), similar to those previously found in the kidney, could also be present in the zona glomerulosa cells of spontaneously hypertensive rats (SHR) and salt-sensitive Dahl rats (S rats). We found an attenuated aldosterone (Aldo) response to angiotensin II (ANG II) in zona glomerulosa cell suspensions isolated from hypertensive SHR compared with those from Wistar-Kyoto (WKY) rats, whereas cells derived from hypertensive S rats showed a significantly higher Aldo response to the maximum stimulatory dose of ANG II than those from salt-resistant Dahl rats (R rats). The maximum observed Aldo responses to ACTH stimulation were not different in SHR or S rats compared with their respective controls. ANF exerted a potent inhibitory action on both ANG II- and ACTH-stimulated secretions of glomerulosa cell suspensions, without any difference in its potency between hypertensive and control rats. The equipotent inhibitory action of ANF on the ANG II- and ACTH-stimulated secretion of Aldo in those cell suspensions suggests that the previously observed alterations in the target cell responsiveness to ANF do not exist in the adrenal zona glomerulosa cells of SHR and Dahl S rats.

Adrenocorticotropic Hormone↗
PubMed1986

Involvement of the adrenal glands in the action of the atrial natriuretic factor.

Adrenalectomized, medullectomized and sham operated rats were treated with either a chronic infusion or a bolus injection of the synthetic atrial natriuretic factor (ANF). ANF did not enhance natriuresis and diuresis in sham operated conscious animals during chronic infusion, but it had a potent action when injected as a bolus into anesthetized rats. The absence of the whole adrenal glands, but not adrenal medulla profoundly modified the renal response to ANF: a) following chronic administration of ANF, the baseline natriuresis paradoxically decreased in adrenalectomized rats, and b) in response to a bolus injection of ANF the natriuretic and diuretic actions of the peptide were attenuated in these animals. The medullectomy-induced decreased natriuresis and dopamine excretion were corrected by ANF infusion. Furthermore, ANF suppressed the compensatory increase of norepinephrine excretion secondary to adrenalectomy. The data suggest that the presence of the adrenal cortex is necessary for the natriuretic and diuretic actions of ANF. The decrease in urinary DA excretion may reflect diminished dopaminergic activity and contribute to the post-medullectomy antinatriuresis, a phenomenon which can be corrected by ANF infusion. ANF may also have a depressing activity on the increased sympathetic tone.

Adrenal Glands↗
PubMed1986

Atrial natriuretic factor inhibits the sympathetic nervous activity in one-kidney, one-clip hypertension in the rat.

The one-kidney, one-clip model of rat hypertension was found to have an increased natriuresis following chronic infusion of atrial natriuretic factor (ANF). We have now found that this natriuretic effect of ANF is associated with a suppression of the initially elevated urinary excretion of norepinephrine and epinephrine and increase of the excretion of the main dopamine metabolite-dihydroxyphenylacetic acid as well as of the urinary dopamine to norepinephrine ratio. These data are compatible with the hypothesis that ANF suppresses the increased sympathetic activity in this model of hypertension and this action combined with opposite changes of dopamine may contribute to the natriuretic effect of ANF.

Animals↗
PubMed1986

The blood pressure decrease-induced sympathetic discharge following atrial natriuretic factor administration may offset its natriuretic action.

Conscious SHR and WKY rats were infused during 7 days with ANF (Arg 101-Tyr 126), 100 ng/hr/rat, by means of miniosmotic pumps and their basal blood pressure (BP), changes in sodium excretion and urinary catecholamines compared with those at the last day of the infusion. The SHR initial BP of 181 +/- 3 mmHg gradually declined to 137 +/- 5 mmHg. No significant change in blood pressure was observed in the ANF-infused WKY group. However, WKY rats exhibited an increased sodium excretion and urinary dopamine/norepinephrine ratio when compared to sham-infused rats. No such differences were observed in SHR. It is suggested that an ANF-induced withdrawal of the renal sympathetic tone permits the manifestation of its natriuretic action in WKY rats. When, however, a BP decrease predominates, as in SHR, this decrease results in a reflex sympathetic discharge with a renal sympathetic activity over-riding the ANF induced natriuresis seen in WKY rats. Secondary sympathetic responses to the ANF-induced BP decrease have to be thus taken into account when a dissociation between the hypotensive and natriuretic action of ANF is observed in vivo.

Animals↗
PubMed1985

Gluco- and mineralocorticoids may regulate the natriuretic effect and the synthesis and release of atrial natriuretic factor by the rat atria in vivo.

Adrenalectomy abolished the acute natriuretic effect of ANF which was partially restored to about 50% by combined therapy with gluco- and mineralocorticoids. It is suggested that the lack of effect of ANF may be due to a decreased renal vascular reactivity to the peptide in adrenalectomized animals. Simultaneous administration of Dexamethasone and Deoxycorticosterone acetate to adrenalectomized rats produced a marked increase in immunoreactive ANF in atrial tissue and plasma. The administration of NaCl to these animals produced a relatively lower concentration of atrial ANF and a further increase in plasma ANF. Our results suggest that glucocorticoids may regulate synthesis and release of ANF by the atria and mineralocorticoids may have a permissive role. Furthermore, the presence of steroids is necessary for the NaCl-stimulated ANF release.

Adrenalectomy↗
PubMedDate not supplied

An atrial natriuretic factor-like activity in rat posterior hypophysis.

An atrial natriuretic factor-(ANF) like immunoreactivity (IR-ANF), is present in the posterior hypophysis of the rat. In order to obtain more direct information on the presence and biological activity of this new posterior hypophysis peptide, we applied a procedure similar to that described for rat atria, to extract an ANF-like material from the posterior hypophysis of the rat. An analysis of the tissue extracts by reverse-phase high performance liquid chromatography (RP-HPLC) suggested that, in this organ, the ANF-like peptides may be present in multiple forms: a low molecular weight peptide which had a RP-HPLC pattern similar to that of the synthetic rat 28 amino acid C-terminal (Ser 99-Tyr 126) ANF, and an unidentified higher molecular weight peptide. The partially purified low molecular weight peptide was found to have a potency similar to that of synthetic rat ANF in the inhibition of adrenocorticotropin-stimulated aldosterone secretion in dispersed zona glomerulosa cells, suggesting that the ANF-like peptide was biologically active. Immunohistochemical visualization of the ANF-like peptides revealed the distribution of the peptide within the posterior hypophysis. There was no immunohistochemical staining for ANF in the intermediate lobe. These results suggest the existence of biologically active ANF-like peptides within the posterior hypophysis of the rat. It is possible that these peptides may modulate locally the posterior hypophysis hormone secretion.

Adrenal Glands↗
PubMedDate not supplied

Atrial natriuretic factor in the spinal cord of normotensive and hypertensive rats.

Atrial natriuretic factor (ANF) was investigated in the rat spinal cord and hypothalamus using two radioimmunoassays. ANF was also quantified in both tissues of Spontaneously Hypertensive Rats and Dahl rats. Spinal cord and hypothalamus were found to be immunoreactive to proANF and its near-NH2- or near-COOH-terminal fragments. A major part of the extracted ANF was a COOH-terminal peptide smaller than or the same as ANF (Ser99-Tyr 126). SHR had higher hypothalamic and spinal cord ANF concentrations than Wistar Kyoto rats, while the Dahl salt-sensitive animals exhibited an increase in spinal cord ANF when compared with the Dahl salt-resistant group. The data suggest that spinal cord may produce ANF locally with processing similar to that in hypothalamus. Changes in ANF concentrations occurring during the course of hypertension remain to be further investigated.

Animals↗
PubMedDate not supplied

Effect of prolonged high salt intake on atrial natriuretic factor's kinetics in rats.

Plasma atrial natriuretic factor (ANF) paradoxically decreases after 5 weeks (but not after 3 weeks) of 8% NaCl intake in normotensive rats. As this phenomenon remains unaccounted for by changes in ANF production, we studied the disappearance of [125I]ANF(99-126) from the circulation as an alternative explanation of plasma ANF decline. Following 5 weeks (but not 3 weeks) of an 8% NaCl diet, plasma concentrations of [125I]ANF were significantly decreased and metabolic clearance rate and volume of distribution were increased compared to control rats fed a 0.8% NaCl diet. By studying [125I]ANF tissue uptake we noted significantly greater peptide uptake after 5 weeks (but not after 3 weeks) of high salt consumption in several tissues. We hypothesize that prolonged (at least 5 weeks) 8% NaCl ingestion increases the density and/or affinity of ANF binding sites. These changes may be responsible for the previously observed decline in plasma ANF concentrations after a prolonged high salt intake.

Animals↗
PubMedDate not supplied

Molecular targeting of malignant gliomas with novel multiply-mutated interleukin 13-based cytotoxins.

A vast majority of high-grade gliomas over-express a receptor for interleukin 13 (IL13). This glioma-associated receptor for IL13 is interleukin 4 (IL4)-independent. This is in contrast to the physiological and IL4-shared receptor for the IL13, IL13/4 receptor, which is found on many normal organs. IL13-based Pseudomonas exotoxin (PE)-containing cytotoxic fusion proteins have been shown to be very potent anti-glioma agents. However, native IL13-based cytotoxins interact with both forms of the IL13 receptor. Therefore, mutations in IL13 were made in order to diminish/eliminate IL13's interaction with the shared IL13/4 receptor of normal tissue. These mutations encompassed amino acids located on alpha-helix A and C of IL13. We have engineered double or triple mutants of IL13 linked to various forms of PE. We found that these mutations could be successfully incorporated into IL13 without the loss of the protein's ability to selectively deliver the toxin to glioma cells while reducing their toxicity.

Cell Survival↗
PubMedDate not supplied

An immunotoxin with increased activity and homogeneity produced by reducing the number of lysine residues in recombinant Pseudomonas exotoxin.

Pseudomonas exotoxin A (PE) is a protein composed of 613 amino acids arranged into three major, and one minor, domains. Immunotoxins (ITs) containing PE38, a mutant form of PE which lacks the cell binding domain (Ia, amino acids 1-252) and 16 amino acids from domain Ib (amino acids 365-380), are extremely potent cytotoxic agents which can cause a complete regression of various human carcinomas grown in nude mice. However, these ITs are a mixture of several different chemical forms since the coupling between the antibody and the toxin may occur between either the light or heavy chain of the antibody and one of the four primary amino groups present on the truncated toxin. To modify the toxin with heterobifunctional crosslinking reagents only at specific sites, we replaced lysines 590 and 606 with glutamines and lysine 613 with arginine (PE38QQR). We also added two different peptide sequences, each containing a lysine residue, at the N-terminus of PE38. In one of these the sequence is ANLAEEAFK ("Lys" peptide), and in the other, the sequence is LQGTKLMAEE ("NLys" peptide). The mutant toxins were coupled using a thioether linkage to monoclonal antibody B3 which recognizes an antigen present in large amounts on many human cancers. PE38QQR-containing recombinant toxins can only be linked to an antibody through the N-terminal methionine or the lysine within the peptide.(ABSTRACT TRUNCATED AT 250 WORDS)

ADP Ribose Transferases↗
PubMedDate not supplied

Pancreatic cancer cells express interleukin-13 and -4 receptors, and their growth is inhibited by Pseudomonas exotoxin coupled to interleukin-13 and -4.

BACKGROUND: Interleukin (IL)-13 and -4 are multifunctional cytokines that bind to specific cell-surface receptors. The aim of this study was to determine whether pancreatic cancer cells express either receptor, and to assess the growth suppressive effects of chimeric proteins composed of a Pseudomonas exotoxin (PE) A mutant (PE38QQR) fused to IL-13 (IL-13-PE38QQR) or IL-4 (IL-4-PE38QQR) in these cells. MATERIALS AND METHODS: Northern and Western blot analysis were used to analyze the expression of IL-4/-13 receptors and the common gamma chain (gamma c) in pancreatic cancer cell lines. MTT growth assays were carried out to assess the effects of IL-4/-13 and IL-4/-13-PE38QQR on cell growth. RESULTS: All 6 pancreatic cancer cell lines examined expressed IL-13R alpha 1 and IL-4R alpha, one cell line expressed IL-13R alpha 2, and 5 pancreatic cancer cell lines expressed gamma c. IL-13 (5 nM) significantly enhanced the growth of 3 cell lines, whereas IL-4 (5 nM) enhanced the growth of 1 cell line. In contrast, IL-13-PE38QQR and IL-4-PE38QQR inhibited the growth of all 6 tested cell lines. There were large variations in the individual sensitivity of the cells, with LD50 values ranging from 100 ng/ml to 5 micrograms/ml for IL-13-PE38QQR and from 20 ng/ml to 10 micrograms/ml for IL-4-PE38QQR. IL-13 and -4 antagonized these inhibitory activities in some, but not all, of the cell lines. CONCLUSIONS: IL-13 and -4 may act as mitogens toward pancreatic cancer cells by activating IL-4- and IL-13-receptors and IL-13- and IL-4-coupled toxins may ultimately have a role in the treatment of pancreatic cancer.

ADP Ribose Transferases↗