[54] The preparation of acylated derivatives of cyclic nucleotides

Posternak, Th.; Weimann, G.

doi:10.1016/0076-6879(74)38057-3

Cited by 46 publications

(25 citation statements)

References 8 publications

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“…In that case, the inability of PGE2 to modify the effects of db-cAMP on JnV and Ve (Figs. 6, 7) may have been referable to the resistance of db-cAMP to phosphodiesterase hydrolysis (59). We consider this possibility unlikely since the observations of Edwards et al (56) indicate that, in a variety of murine nephron segments, prostaglandins have no effect on phosphodiesterase activity.…”

Section: Discussionmentioning

confidence: 79%

Interactions among prostaglandin E2, antidiuretic hormone, and cyclic adenosine monophosphate in modulating Cl- absorption in single mouse medullary thick ascending limbs of Henle.

Culpepper¹,

Andreoli²

1983

J. Clin. Invest.

109

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A B S T R A C T This paper describes the inhibitory effect of prostaglandin E2 (PGE2) on antidiuretic hormone (ADH)-stimulated net Cl-absorption and spontaneous transepithelial voltage (Ve) in single medullary thick ascending limbs of Henle (TALH, thick ascending limb; mTALH, medullary segment; cTALH, cortical segment) obtained from mouse kidney. The experimental data indicate that PGE2 reduced the ADHdependent values of net Cl-absorption (Je,', eq cm-2 s-') and Ve (mV) in a dose-dependent manner; that increasing concentrations of peritubular ADH reversed the PGE2-mediated reductions in the ADH-dependent moiety of Ve in the mouse mTALH; that PGE2 had no effect on cyclic AMP-stimulated increments in Ve in the mouse mTALH; and that PGE2 had no In the renal medulla, this process enriches medullary osmolality, thereby contributing to urinary concentrating power (13,14). In certain species, like the mouse, salt absorption (11) and adenyl cyclase activity (15,16) in the water permeability of mammalian collecting ducts.In the isolated mouse mTALH, NaCl absorption involves the coupled entry of Cl-, and possibly K+ (17, 18), to Na+ entry across apical plasma membranes. In other words, Cl-transport in this nephron segment is a secondary active transport process, driven in part by the Na+ gradient between luminal fluid and cell interior (11,17). Conservative NaCl absorption in this nephron segment is enhanced considerably, and in a dose-dependent manner, by ADH, operating through the second messenger cyclic (c)AMP (11). Conversely, conservative NaCl absorption in the mouse mTALH is suppressed significantly by increases in peritubular osmolality independently of transepithelial osmotic pressure gradients (19).The mouse mTALH, like the rabbit cTALH (6, 20) and mTALH (7), behaves as a hybrid epithelium: the mouse mTALH is electrically leaky (11, 17) and rather permeable to Na+ and to 17), yet is virtually water impermeable either in the presence or absence of ADH (9-11). Consequently, as medullary peritubular salt concentrations vary, there occur varying degrees of dissipative NaCl backleak from interstitium to lumen through the paracellular pathway. Thus, for the mouse mTALH, maintenance of diluting power in the presence of varying NaCl concentrations in peritubular media depends, at least in part, on the interplay between ADH and peritubular osmolality in modifying conservative NaCl transport (11, 19). We will argue in this paper that PGE2 represents yet another factor that modulates the latter in the mouse mTALH.In the amphibian urinary bladder, Orloff et al. (21) found that prostaglandins inhibited the hydro6smotic effect of ADH but did not change the response of the epithelium to cAMP. They inferred that prostaglandins had acted at a locus proximal to hormone-dependent accumulation of cAMP within the cell, with little or no discernible prostaglandin action on transport events beyond cAMP accumulation. Based on in vitro studies in the isolated rabbit collecting duct, Grantham and Orloff (22) also suggested that prosta...

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Section: Discussionmentioning

confidence: 79%

Interactions among prostaglandin E2, antidiuretic hormone, and cyclic adenosine monophosphate in modulating Cl- absorption in single mouse medullary thick ascending limbs of Henle.

Culpepper¹,

Andreoli²

1983

J. Clin. Invest.

109

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“…However, the ad dition of either 5 m M cAMP or 0.5 mM cAMP-N6,0 2-dioctanoyl gave a marked ncubation lime, h decrease of enzyme production in the five isolates tested. It is well established that an increase in intracellular cAMP concentra tions can be achieved either by high ex tracellular concentrations [15] or by modi fied molecules [5,12]. The derivative cAMP-S failed to influence (3-lactamase production, but this may be attributed to poor penetration of this molecule through the outer membrane of P. mallophilia.…”

Section: Discussionmentioning

confidence: 97%

Heterogeneity of Beta-Lactamase Production in Pseudomonas maltophilia, a Nosocomial Pathogen

Cullmann

Dick

1990

Chemotherapy

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Twenty Pseudomonas maltophilia isolates were examined for susceptibility to β-lactam antibiotics, including carbapenems, and for β-lactamase production. All the isolates were resistant to imipenem (MICs 64–512 mg/l) and to a lesser extent, to meropenem (MICs 16–256 mg/l). None of the isolates produced significant amounts of β-lactamase without induction. Among the β-lactams studied imipenem proved to be the most potent inducer; meropenem was a weaker inducer. Interestingly, 6-amino-penicil-lanic acid, even in concentrations up to 100 mg/l, entirely lacked induction activity. In any case enzyme production was drug concentration dependent and transient. Isoelectric focusing revealed 6 different enzymes distinguished by their different isoelectric points (pH 6.2, 8.3, 8.5, 9.0, 9.2 and 9.4). This suggested the lack of a unique β-lactamase profile in P. maltophilia. Addition of 5 mM cyclic AMP (cAMP) or 0.5 mM cAMP-N⁶, O²-dioctanoyl (a lipophilic derivative) resulted in a marked drop of β-lactamase induction by imipenem as compared to the control assay. Monitoring of carbapenem hydrolysis by cell-free supernatants revealed inactivation of both carbapenems. Meropenem was inactivated about 5 times more rapidly than imipenem. Our studies revealed that β-lactamase production in P. maltophilia as well as growth kinetics were influenced to a considerable extent by the nutrient medium employed.

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“…[28][29][30] It has also been reported that PE facilitates PKC activation by phosphatidylserine 16) and HUFA potentiates PKC activity. 31) To elucidate the contribution of protein kinases to the expression of the enhancing effect, we further investigated the effects of PKA and PKC inhibitors on dbcAMPinduced differentiation, respectively.…”

Section: Discussionmentioning

confidence: 99%

Synergistic Effects of Highly Unsaturated Fatty Acid‐containing Phosphatidyl‐ethanolamine on Differentiation of Human Leukemia HL‐60 Cells by Dibutyryl Cyclic Adenosine Monophosphate

Hosokawa¹,

Sato²,

Ishigamori³

et al. 2001

Japanese Journal of Cancer Research

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[54] The preparation of acylated derivatives of cyclic nucleotides

Cited by 46 publications

References 8 publications

Interactions among prostaglandin E2, antidiuretic hormone, and cyclic adenosine monophosphate in modulating Cl- absorption in single mouse medullary thick ascending limbs of Henle.

Interactions among prostaglandin E2, antidiuretic hormone, and cyclic adenosine monophosphate in modulating Cl- absorption in single mouse medullary thick ascending limbs of Henle.

Heterogeneity of Beta-Lactamase Production in Pseudomonas maltophilia, a Nosocomial Pathogen

Synergistic Effects of Highly Unsaturated Fatty Acid‐containing Phosphatidyl‐ethanolamine on Differentiation of Human Leukemia HL‐60 Cells by Dibutyryl Cyclic Adenosine Monophosphate

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