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M Manning

Publications and source records attributed to M Manning.

At least 145 records · Page 8Linked to original sources
PubMed1981

Synthetic antagonists of in vivo antidiuretic and vasopressor responses to arginine-vasopressin.

Four analogues of [1-(beta-mercapto-beta, beta-cyclopentamethylenepropionic acid),4-valine,8-D-arginine]vasopressin [d-(CH2)5 VDAVP] and four analogues of its L-arginine isomer d(CH2)5 VAVP with O-methyl-, O-ethyl, O-isopropyl, and O-n-propyltyrosine substituents at position 2 were prepared by the solid-phase method using a slightly modified reoxidation procedure following deblocking with sodium in liquid ammonia to overcome losses due to insolubility. These analogues are the following: 1, d(CH2)5Tyr(Me)VDAVP;2, d(CH2)5Tyr(Et)VDAVP; 3, d(CH2)5Tyr(i-Pr)VDAVP; 4, d(CH2)5Tyr(n-Pr)VDAVP; 5, d(CH2)5Tyr(Me)VAVP; 6, d(CH2)5Tyr(Et)VAVP; 7, d(CH2)5Tyr(i-Pr)VAVP; 8, d(CH2)5Tyr(n-Pr)VAVP. These analogues were tested for agonistic and antagonistic activities in rat antidiuretic and rat vasopressor assay systems. All eight analogues cause a transient antidiuresis when injected intravenously and effectively antagonize antidiuretic responses to subsequent injections of arginine-vasopressin (AVP). They exhibit the following antiantidiuretic pA2 values: 1, 6.68 +/- 0.11; 2, 7.10 +/- 0.08; 3, 6.88 +/- 0.07; 4, 6.67 +/0 0.05; 5, 7.35 +/- 0.06; 6, 7.57 +/- 0.06; 7, 7.32 +/- 0.10; 8, 7.29 +/- 0.07. They are also highly effective antagonists of the vasopressor responses to AVP, with antivasopressor pA2 values in the range of 7.86 to 8.44. These findings indicate tht in this series O-ethyl substitution on the tyrosine at position 2 is optimal for antiantidiuretic potency and that L-arginine is far superior to D-arginine in this regard also. Thus, d(CH2)5Tyr(Et)VAVP with an antiantidiuretic pA2 of 7.57 +/- 0.06 is the most potent of these eight antidiuretic antagonists. These are the first known effective antagonists of in vivo antidiuretic responses to AVP. They are, thus, potentially useful pharmacological tools for studies on the roles of AVP in regulating water balance in normal and pathophysiological states in animals and in humans. They also serve as excellent lead compounds for the design of even more potent antagonists for potential therapeutic use for the treatment of hyponatremia secondary to inappropriate secretion of the antidiuretic hormone (SIADH or the Schwartz-Barter syndrome).

Animals↗
PubMed1981

Mechanism of coliphage M13 contraction: intermediate structures trapped at low temperatures.

The filamentous coliphage M13 can be transformed into a spherical particle (termed spheroid) by exposure to an interface of water and slightly polar but hydrophobic solvent such as chloroform-water at 24 degrees C. We report here that exposure of M13 filaments to a chloroform-water interface at 2 degrees C trapped the phage particles in forms morphologically intermediate to filaments and spheroids. These structures were rods 250 nm long and 15 nm wide, and each had a closed, slightly pointed end, an open flaired end, and a hollow central channel. The final contraction of these intermediates (termed I-forms) into spheroids was dependent upon both temperature and the presence of the solvent-water interface but was apparently independent of both the minor phage coat proteins and the virion DNA. Although stable in an aqueous environment, I-forms, in contrast to filaments, were readily disrupted by detergents, suggesting that the phage structure had been altered to a form more easily solubilized by membrane lipids. These solvent-induced changes might be related to the initial steps of phage penetration in vivo.

Chloroform↗
PubMed1981

Vascular effects of arginine vasopressin during fluid deprivation in the rat.

The vascular effects of arginine vasopressin (AVP) were examined in conscious Sprague-Dawley rats. In six control rats, synthetic AVP at a dose of 40 ng/kg, injected as an intravenous bolus, resulted in a rise in mean arterial blood pressure (BP) from 127 to 149 mm Hg (P < 0.005). No tachyphylaxis was observed after a second AVP bolus administered 30 min later, as BP increased from 125 to 150 mm Hg, P < 0.005. In a second group of six rats, 1-deamino penicillamine, 2-(O-methyl) tyrosine AVP ([dPTyr (Me)]AVP), was administered intravenously at a dose of 10 mug/kg, just before the second AVP bolus. In this group of studies BP rose from 124 to 150 mm Hg (P < 0.01) after the first AVP bolus, but not after the second AVP bolus, which was administered after [dPTyr (Me)]AVP (129 vs. 129 mm Hg, NS). To assess the effect of this AVP pressor antagonist on BP in rats with suppressed endogenous vasopressin, six water-diuresing rats (mean urinary osmolality, 99 mosmol/kg H(2)O) were administered the analogue at the same dose as the first group of rats. The analogue exerted no demonstrable effect on mean BP (128 before vs. 129 mm Hg after [dPTyr (Me)]AVP, NS). In these rats, mean radioimmunoassayable levels of AVP were at or below the detectable limits of our assay (0.5 pg/ml). In contrast, six rats in which endogenous AVP was stimulated by fluid deprivation for 24 h (mean urinary osmolality, 2,489 mosmol/kg H(2)O and mean AVP level of 21.6 pg/ml) had a marked fall in BP when administered the AVP analogue. In these animals [dPTyr (Me)]AVP caused a fall in BP from 124 to 110 mm Hg (P < 0.005). This fall in blood pressure was due to a fall in peripheral vascular resistance (0.35 vs. 0.30 mm Hg/ml per min per kg, P < 0.02) after [dPTyr (Me)]AVP, as cardiac index remained unchanged. To eliminate the possibility that this AVP analogue was antagonistic to endogenous pressor substances other than AVP, additional studies were performed. In homozygous Brattleboro (diabetes insipidus) rats receiving exogenous AVP, the vasopressin analogue lowered BP (133 to 112 mm Hg, P < 0.001), but failed to lower BP (112 vs. 112 mm Hg) in rats not receiving AVP. BP in a group of bilaterally nephrectomized Sprague-Dawley rats, after 24 h of fluid deprivation, fell from 130 to 118 mm Hg (P < 0.02) after the AVP analogue, precluding an effect of the analogue on lowering BP by inhibiting the renin-angiotensin system. Finally, the AVP analogue failed to alter the pressor response to exogenous infusions of either norepinephrine or angiotensin II. These results demonstrate that (a) the AVP analogue [dPTyr (Me)]AVP abolishes the pressor effect of large exogenous doses of AVP; (b) the analogue has no effect on BP in rats with suppressed or absent endogenous AVP; (c) the depressor effect of the analogue does not involve antagonism of the vasoconstrictors, norepinephrine or angiotensin; and (d) most importantly, BP fell significantly after AVP antagonist administration in intact, conscious, fluid-deprived rats with elevated endogenous AVP levels. This effect of the AVP antagonist to block endogenous AVP and lower BP was primarily due to a fall in peripheral vascular resistance.

Angiotensin II↗
PubMed1981

Diabetes induced with multiple subdiabetogenic doses of streptozotocin: lack of protection by exogenous superoxide dismutase.

The addition of exogenous superoxide dismutase (SOD) was examined as a possible means of protecting B-cells of mice against either the immediate or delayed toxicity caused by multiple injections of low doses of streptozotocin (Sz). Three different routes of SOD administration (i.p. and i.v. injection and continuous s.c. infusion) and several different doses and schedules were tried. In addition, a long-acting derivative of SOD was synthesized and tested. Despite the observation of a modest delay in the onset of diabetes in one experiment, no protective effect of SOD on the progressive elevation of blood glucose concentrations was evident in the majority of studies. Moreover, a loss in pancreatic insulin content and a tripling of pancreatic glucagon content occurred in all mice treated with low dosages of Sz, irrespective of whether or not either SOD or a long-acting derivative of SOD was administered. Finally, in parallel experiments in vitro, this enzyme was ineffective in protecting isolated rat islets from the acute toxicity of exposure to Sz on glucose-stimulated insulin release.

Animals↗
PubMed1981

Vasopressin in the rat with partial nephrectomy-salt hypertension.

The role of vasopressin in the pathogenesis of partial nephrectomy (PN)-salt hypertension was examined in the rat. Hypertension was produced by reducing renal mass 70% and substituting 1% saline for drinking water 2 to 4 days after surgery. PN alone resulted in an increase in systolic blood pressure. Subsequent salt loading led to a further large increase in arterial pressure. On the second to third day after substitution of saline for drinking water, urinary vasopressin excretion (UADHV) was increased six-fold and the plasma vasopressin concentration was increased two and one-half-fold. UADHV then fell to a level that was three-fold greater than control values 5 days later. Although there was a marked stimulation of vasopressin release during the period of salt loading, a vasopressin pressor antagonist had only a small effect on arterial pressure. This suggests vasopressin is not a major pressor agent in PN-salt hypertension.

Animals↗
PubMed1981

Combination chemotherapy with cisplatin, bleomycin, and methotrexate in patients with advanced head and neck cancer.

Twenty-six patients with advanced head and neck cancer, 22 of whom had failed prior surgery and/or radiotherapy, were treated with a combination regimen of cis-diamminedichloroplatinum II, bleomycin, and methotrexate. There were no complete responses. Nine patients achieved a partial response (35%). Three of the four (75%) patients without prior therapy achieved a partial response while only 6 of the 22 patients (27%) with prior surgery and/or radiation therapy obtained a partial response. The median response duration was 3 months. Patients with a partial response did not live significantly longer than those who did not live significantly longer than those who did not respond. Toxic reactions were frequent: there were three episodes of sepsis secondary to leukopenia and two cases of bleomycin pulmonary toxicity. Mucositis was noted in 40% and nausea and vomiting in 60% of patients. We conclude that this triple-drug regimen has little value in the treatment of patients with advanced squamous cell carcinoma of the head and neck who have failed prior surgery and radiotherapy.

Adult↗
PubMed1980

Design and synthesis of potent in vivo antagonists of oxytocin.

We have previously shown that the substitution of 8-ornithine and 2-O-methyltyrosine alone and in combination in [1-deaminopenicillamine] oxytocin (dPOT) brought about enhancements in antagonistic potencies to responses to oxytocin in vivo. To explore the effects of these substitutions in analogs of dPOT containing larger alkyl substitutents on the beta carbon at position 1 and on the tyrosine residue at position two, the following six analogs were synthesized: [1-(beta-mercapto-beta, beta-diethylpropionic acid), 8-ornithine] vasotocin (1, dEt2OVT); (1-beta-mercapto-beta, beta-cyclopentamethylenepropionic acid), 8-ornithine] vasotocin (2, d(CH2)5OVT): [1-beta-mercapto-beta, beta-diethylpropionic acid), 2-O-methyltyrosine, 8-ornithine]vasotocin [3, dEt2 Tyr(Me)OVT]; [1-(beta-mercapto-beta, beta-diethylpropionic acid), 2-O-ethyltyrosine, 8-ornithine]vasotocin [4, dEt2 Tyr(Et)OVT]; [1-beta-mercapto-beta', beta-cyclopentamethylenepropionic acid), 2-O-methyltyrosine, 8-ornithine]vasotocin [5, d(CH2)5 Tyr(me)OVT]: [1-beta-mercapto-beta, beta-cyclopentamethylenepropionic acid), 2-O-methyltyrosine, 8-ornithine]vasotocin [6,d(CH2)5 Tyr(Et)OVT]. The required protected intermediates were synthesized by a combination of solid-phase synthesis and by individual 8 + 1 couplings in solution. All six analogs antagonize the actions of oxytocin on the rat uterus in the absence of Mg2+, in the presence of 0.5 mM Mg2+ and in situ. They also antagonize milk ejection responses to oxytocin, and the vasopressor responses to arginine vasopressin, and all have very low antidiuretic activities. With pA2 values of 7.35 +/- 0.08 and 7.37 +/- 0.17, respectively, compounds 3 and 5 are the two most potent in vivo antagonists of oxytocin reported to date.

Amino Acid Sequence↗
PubMed1980

Analysis of cytoplasmic antigens of the yeast and mycelial phases of Candida albicans by two-dimensional electrophoresis.

The extent of the macromolecular change accompanying yeast to mycelium morphogenesis of Candida albicans was analyzed by two-dimensional gel electrophoresis of the cytoplasmic proteins of the two growth forms after antibody cross-absorption experiments. Pure cultures of yeasts and true hyphae (i.e., without concomitant production of pseudohyphae) were grown in a synthetic low-sulfate medium (LSM). The two strains selected for this study were strain 4918, which produces pure mycelial (M) cultures in LSM at 37 degrees C (designated 4918-37M) and yeasts (Y) at 24 degrees C (4918-24Y), and strain 2252, which produces yeasts exclusively at both 24 and 37 degrees C in LSM (2252-24Y and 2252-37Y). The proteins of both strains were labeled at both temperatures with [35S]sulfate, and cytoplasmic fractions were prepared by mechanical disruption and ultracentrifugation. Rabbits were immunized with the 4918-24Y and 4918-37M cytoplasmic fractions to produce anti-yeast-phase and anti-mycelial-phase hyperimmune sera. Each radiolabeled cytoplasmic fraction was absorbed with anti-mycelial-phase immunoglobulin, anti-yeast immunoglobulin, and immunoglobulin from normal rabbit serum. Staphyloccal protein A was used to remove immune complexes. The labeled, nonabsorbed proteins were also analyzed by two-dimensional electrophoresis. Highly reproducible protein spot patterns were obtained which defined hundreds of proteins in each extract. The specificity of the immunoglobulin hundreds of proteins in each extract. The specificity of the immunoglobulin preparations was extremely broad, and as many as 168 cytoplasmic antigens were detected. Eighty-three antigens were recognized in the mycelial-phase extract only by the anti-mycelial-phase immunoglobulin. However, comparative analysis revealed that all of these proteins were present in at least one other extract. Therefore, none of them was unique to the mycelial morphology. Eleven antigens were detected in the 2252-37Y extract that were not present in the extracts from strain 4918, which indicates that proteins obtained from different strains may express similar antigenic determinants, but differ in their physiochemical properties.

Antigens↗
PubMed1980

Strain variation and morphogenesis of yeast- and mycelial-phase Candida albicans in low-sulfate, synthetic medium.

A low-sulfate synthetic medium was developed in which pure cultures of yeast- and mycelial-phase Candida albicans could be cultivated for investigations of the molecular biology of dimorphism. The medium contained ammonium ions, phosphate buffer, salts, glucose, and biotin. Morphogenesis was found to be dependent upon the strain of C. albicans. Of six strains tested in the low-sulfate medium at 37 degrees C, three formed mixed cultures of yeasts, true mycelium and pseudomycelium, two formed pure cultures of true mycelium, and one maintained yeast growth. All six strains produced pure cultures of yeasts at 24 degrees C. The buffering capacity of the medium maintained the pH at 6.9 even at high-density cell growth. The low concentration of sulfate and the absence of amino acids in the medium provided conditions in which to radiolabel cellular constituents with [35S]sulfate. For molecular investigations, the use of two strains is suggested, one forming yeasts and one forming true mycelium in low-sulfate medium at 37 degrees C, thus providing controls for both strain variation and for molecular changes induced by environmental change but unrelated to morphogenesis.

Amino Acids↗
PubMed1980

Morphogenesis of Candida albicans and cytoplasmic proteins associated with differences in morphology, strain, or temperature.

The extent of change in cytoplasmic proteins which accompanies yeast-to-mycelium morphogenesis of Candida albicans was analyzed by two-dimensional gel electrophoresis. Pure cultures of yeasts and true hyphae (i.e., without concomitant production of pseudohyphae) were grown in a synthetic low-sulfate medium. The two strains selected for this study were strain 4918, which produces pure mycelial cultures in low-sulfate medium at 37 degrees C and yeast cells at 24 degrees C, and strain 2252, which produces yeast cells exclusively at both 24 and 37 degrees C in low-sulfate medium. The proteins of both strains were labeled at both temperatures with [35S]sulfate, cytoplasmic fractions were prepared by mechanical disruption and ultracentrifugation, and the labeled proteins were analyzed by two-dimensional electrophoresis. Highly reproducible protein spot patterns were obtained which defined hundreds of proteins in each extract. Ten protein spots were identified on the two-dimensional gels of the 4918 mycelial-phase extract which were not present in the 4918 yeast-phase extract. These proteins appeared to be modifications of preexisting yeast-phase proteins rather than proteins synthesized de novo in the mycelial cells because 5 were absorbed by rabbit anti-yeast-phase immunoglobulin and each of the 10 was also present in extracts of strain 2252 grown at 24 and 37 degrees C, indicating that they were neither unique to filamentous cells nor sufficient for induction or maintenance of the mycelial morphology. Thirty-three proteins were identified in the 4918 yeast-phase extract which were not present in the 4918 mycelial-phase extract. Pulse-chase experiments revealed the synthesis of new proteins during yeast-to-mycelial conversion, but none of these was unique to mycelial cells. No differences in the major cytoplasmic proteins of any of the yeast- or mycelial-phase extracts were identified. This finding suggests that the major structural proteins of the cytoplasm are not extensively modified and argues instead that proteins unique to either phase may serve a regulatory function.

Autoradiography↗
PubMed1980

The design of effective in vivo antagonists of rat uterus and milk ejection responses to oxytocin.

Several new synthetic analogs of the oxytocin antagonist [1-deaminopenicillamine]oxytocin have been prepared and tested for their abilities to inhibit responses to oxytocin by the isolated rat uterus in the absence and presence of Mg++, by the rat uterus in situ, and by the rat mammary gland in situ. Substituting 2-O-methyltyrosine in [1-deaminopenicillamine]oxytocin strikingly enhances antagonism of all uterin responses, and [1-deaminopenicillamine, 2-O-methyltyrosine]oxytocin and its 4-threonine analog are also potent inhibitors of the milk ejection response. Substituting 2-phenylalanine in [1-deaminopenicillamine]oxytocin also enhances antagonistic activities in all uterine assays, but [1-deaminopenicillamine, 2-phenylalanine]oxytocin retains agonistic activity on milk ejection assays. From these studies we can conclude that changes in the 1-position (1-deaminopenicillamine substitution) and the 2-position (2-O-methyltyrosine or 2-phenylalanine substitution) can have additive effects on antagonistic activities. Substitution of an 8-ornithine also enhances inhibitory potency in vivo, and this effect may also be additive to those of the substitutions in 1- and 2-positions. These findings provide many clues that may lead to the design of even more effective antagonists; several of the analogs reported here appear to the most effective antagonists of oxytocin in vivo yet reported and may be useful agents in further studies on the physiological functions of endogenous oxytocin.

Animals↗
PubMed1980

Natriuretic effect of [7-glycine]oxytocin in the presence of diuretic agents in conscious rats.

Substitution of the amino acid glycine for 7-proline in oxytocin produces an analog, [7-glycine]oxygocin, having markedly reduced antidiuretic and vasopressor activities but retaining considerable natriuretic activity. We administered this analog alone and with distally acting diuretic agents to test the hypothesis that oxytocin and its analogs decrease proximal tubular fluid reabsorption. If [7-glycine]oxytocin shares a common mechanism of action with any of these agents, the response to combined treatment should be less than additive, otherwise, the saluretic effect of both agents should be maintained. Subcutaneous administration of [7-glycine]oxytocin, 10 micrograms/kg, to conscious fluid-loaded rats produced a natriuresis, diuresis and kaliuresis. Hydrochlorothiazide and [7-glycine]oxytocin administered together to the same rats had a greater than additive effect on urine volume and sodium excretion. Furosemide and [7-glycine]oxytocin had an additive effect on urine volume, sodium and chloride excretion. Triamterene blocked the kaliuresis caused by [7-glycine]oxytocin, although the two agents administered together had a greater than additive effect on sodium excretion. These results indicate that [7-glycine]oxytocin does not share a common natriuretic mechanism or site of action with the above diuretics. Our data are consistent with the hypothesis that oxytocin and its analogs may increase urinary sodium excretion by decreasing net proximal tubular fluid reabsorption.

Animals↗
PubMed1979

Synthetic antagonists of in vivo responses by the rat uterus to oxytocin.

As part of a program in which we are attempting to synthesize in vivo antagonists of oxytocin, the following four analogues were synthesized and tested for antagonistic activities in rat uterus and rat vasopressor assay systems: [-(beta-mercapto-beta,beta-diethylpropionic acid), 4-threonine]oxytocin (1, dEt2TOT), [1-beta-mercapto-beta,beta-cyclopenta-methylenepropionic acid), 4-threonine]oxytocin [2, d(CH2)5TOT], [1-deaminopenicillamine,2-O-methyltyrosine]oxytocin [3, dPTyr(Me)OT], and [1-deaminopenicillamine,2-O-methyltyrosine,4-threonine]oxytocin [4, dPTyr(Me)TOT]. The required protected intermediates were synthesized by a combination of solid-phase peptide synthesis and by individual 8 + 1 couplings in solution. All four analogues antagonize the actions of oxytocin on the rat uterus (a) in the absence of Mg2+, (b) in the presence of 0.5 mM Mg2+, and (c) in situ. They exhibit, respectively, the following pA2 values in each of the assay systems a-c: (1) (a) 7.72 +/- 0.11, (b) 7.36 +/- 0.09, (c) 6.47 +/- 0.11; (2) (a) 7.91 +/- 0.13, (b) 7.81 +/- 0.09, (c) 6.94 +/- 0.11; (3) (a) 7.76 +/- 0.12, (b) 7.80 +/- 0.12, (c) 6.86 +/- 0.12; (4) (a) 7.64 +/- 0.14, (b) 7.79 +/- 0.09, (c) 6.84 +/- 0.10. They have the following antivasopressor pA2 values: (1) 6.30 +/- 0.13; (2) 5.86 +/- 0.03; (3) 7.59 +/- 0.05; (4) 7.32 +/- 0.04. Compounds 2-4 are among the most potent in vivo antagonists of oxytocin reported to date.

Animals↗