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Biomedical subjects

E Marley

Publications and source records attributed to E Marley.

At least 19 recordsLinked to original sources
PubMed2005

Determination of Vitamin B12 in food products and in premixes by reversed-phase high performance liquid chromatography and immunoaffinity extraction.

A new, faster and simple method to quantify Vitamin B12, both in foods and in premixes, by reversed-phase liquid chromatography with UV detection has been developed. Vitamin B12 was extracted from food products with 50 mM sodium acetate buffer pH 4.0 (at 100 degrees C for 35 min) in the presence of sodium cyanide, followed by a purification step on an immunoaffinity column prior to the LC analysis. An enzymatic hydrolysis (pepsin at 37 degrees C and pH 4 for 3 h) prior to the purification step efficiently released the bound Vitamin B12, and thus, allowed obtaining total Vitamin B12 content in food products. Vitamin B12 was monitored by UV at 361 nm after its separation on a reversed-phase narrow-bore column with a gradient of mobile phase made of water/acetonitrile and trifluoroacetic acid (TFA) 0.025%. The specificity of the method was demonstrated by the retention characteristics, UV spectra and by comparing the peak purity with the Vitamin B12 standard. The calibration graphs plotted with six concentrations of Vitamin B12 was linear with a regression coefficient R2 > 0.9997. The repeatability of the method was evaluated at different levels of concentration on six fortified products and the relative standard deviation (RSDr) was below 3.2%. The value of the relative standard deviation of the intermediate precision was below 5.6% (n = 4). The method was successfully applied to several food products and consistent results were obtained in comparison with microbiological assay (MBA). Our data demonstrate that the immunoaffinity columns are highly efficient for the purification of Vitamin B12 and that our HPLC could be used as an alternative method to the microbiological assay for the determination of Vitamin B12 in food products.

Chromatography, Affinity↗
PubMed1997

Fetal but not maternal serum cytokine levels correlate with histologic acute placental inflammation.

Our objective was to determine if placental histologic acute inflammation is related to maternal and fetal serum cytokine levels in preterm labor, using a data set previously constructed blinded to histopathologic information. To this goal in 1992, 32 consecutive patients at 20-36 weeks with progressive labor and tocolytic failure were recruited. Maternal serum sampled during the active phase of labor, and fetal (umbilical vein) serum were assayed by ELISA for levels of soluble interleukin-1 beta (IL-1 beta), soluble interleukin-2 receptor (IL-2 R), and interleukin 6 (IL-6) (T-Cell Diagnostics). Acute placental inflammation was scored by two groups blinded to clinical data, and the average scores analyzed for relationships to serum cytokine levels. Weighted kappa values, reflecting interobserver agreement in scoring of acute inflammation, were: amnion 0.84; choriodecidua 0.84; umbilical cord 0.85; and chorionic plate 0.73. Fetal levels of IL-1 beta and IL-2 R were higher with grade 3-4 acute amnionitis than with grades 0-2 (p = 0.022 and p = 0.023). Fetal levels of all three cytokines were higher in grade 3-4 umbilical vasculitis (IL-1 beta p = 0.008, IL-2 R p = 0.01, and IL-6 p = 0.03). In contrast, maternal serum cytokine levels were not associated with presence or severity of histologic evidence of acute placental inflammation. Histologic acute inflammation was not related to duration of labor, interval from membrane rupture to delivery, and presence or duration of antibiotic therapy. We conclude that fetal serum, but not maternal serum cytokine levels, are correlated with histologic evidence of acute placental inflammation, and may reflect a predominant placental origin of the cytokines.

Acute Disease↗
PubMed1991

Covalent coupling of doxorubicin in protein microspheres is a major determinant of tumour drug disposition.

Doxorubicin is shown to be present in albumin microspheres (10-40 microns) in two forms: the native drug and a fraction of drug covalently coupled to the protein matrix probably via glutaraldehyde. Upon trypsin digestion the fraction covalently coupled is released and can be resolved from native doxorubicin by high performance liquid chromatography and quantitated either by using 14C-labelled doxorubicin or by measuring the absorption of the doxorubicin chromophore at 480 nm. Albumin microspheres contained 6.9 micrograms/mg protein covalently bound drug versus 11.1 micrograms/mg native drug when 1% glutaraldehyde was used in microsphere preparation. The covalently bound fraction increased significantly with 2% glutaraldehyde. Albumin/polyaspartic acid microspheres lacked a covalently bound fraction when prepared under the same conditions as pure albumin microspheres (35 micrograms/mg native drug, 1% glutaraldehyde) but transferrin microspheres contained similar amounts of bound and native albumin. In vivo, albumin microspheres altered the disposition of doxorubicin in a rat mammary carcinoma (Sp107) compared to albumin/polyaspartic acid microspheres by reducing the rate of parent drug elimination from the tumour and by reducing its biotransformation to 7-deoxyaglycone metabolites. These data indicate that covalent coupling is a key component in the way doxorubicin is handled in tumours after administration of protein microspheres.

Albumins↗
PubMed1990

Relationship between reductive drug metabolism in tumour tissue of anthracyclines in microspherical form and anti-tumour activity.

Increased activity against a rat solid tumour of doxorubicin incorporated into protein microspheres and administered intratumourally was associated with both increased duration of exposure of tumour tissue to native drug and anaerobic bioreduction of doxorubicin to 7-deoxyaglycones, indicating formation of reactive drug intermediates within tumour tissue. To investigate which of these aspects of drug disposition determined activity we have compared the in vivo fate (clearance from and metabolism by tumour tissue) of doxorubicin in microspherical form with the analogue 4'-deoxydoxorubicin and related this to the tumour growth delay recorded for these drugs. Within the dose range 42 to 55 micrograms, growth delay (14-18 days) of doxorubicin in microspherical form was markedly superior to drug in solution, whereas growth delay of 4'-deoxydoxorubicin in microspherical form (4.3-7.2 days) was not greater than drug in solution. Metabolism to 7-deoxyaglycones by tumour tissue was not a prominent feature of either drug when administered in solution. However, in microspherical form both drugs were extensively metabolized (peak concentrations: 3.6 micrograms/g doxorubicin 7-deoxyaglycone; 2.5 micrograms/g 4'-deoxydoxorubicin 7-deoxyaglycone). Native drug concentrations in tumour tissue were similar after administration in microspherical form at 48 hr (doxorubicin 3.8 micrograms/g; 4'-deoxydoxorubicin 3.7 micrograms/g) and 72 hr (doxorubicin 2.4 micrograms/g; 4'-deoxydoxorubicin 2.7 micrograms/g). At both time points, following administration in microspherical form, tumour tissue concentrations of doxorubicin were significantly greater than when drug was administered in solution, whereas no significant differences were observed for 4'-deoxydoxorubicin. The results are inconsistent with the process of anaerobic bioreduction of doxorubicin to 7-deoxyaglycones being an important component of its anti-tumour activity in microspherical form and point to the importance of increased duration of exposure to native drug.

Animals↗
PubMed1985

Interactions between relatively selective monoamine oxidase inhibitors and an inhibitor of 5-hydroxytryptamine re-uptake, clomipramine.

Features of interactions with combined antidepressants in man were evoked by clomipramine in rats pretreated with both the relatively selective monoamine oxidase (MAO) inhibitors clorgyline and deprenyl, but not when clomipramine was given to rats pretreated with deprenyl or clorgyline alone, i.e. inhibition of both MAO A and B was a likely prerequisite for clomipramine to elicit the syndrome (with the larger dose of clorgyline and deprenyl, MAO A and B inhibition exceeded 95%). The features evoked were myoclonic--forelimb flexor-extensor movements, wet dog shakes and head and body twitches; hyperthermia and ECG anomalies also developed, and locomotor activity was augmented. Myoclonic phenomena were prevented when the above pretreatment also included p-chlorophenyl-alanine, but were unaffected or even intensified when pretreatment instead included alpha-methyl-p-tyrosine; these phenomena were attenuated or abolished by pirenperone, a 5HT2 antagonist. Relevance of these findings to safer combinations of antidepressants is discussed.

Animals↗
PubMed1985

[14C]-beta-phenethylamine, its distribution after administration by various routes to cats, and the effects of monoamine oxidase inhibitors.

[14C]-beta-phenethylamine [( 14C]-PEA) was instilled intragastrically, intraduodenally (i.d.) or infused into the portal vein or femoral artery of cats, anaesthetized with chloralose, to investigate its distribution in the body. [14C]-PEA and phenylacetic acid (PAA) accounted for approximately 85% of radioactivity recovered in blood from control cats or those pretreated with deprenyl or mebanazine. Progressively greater portal venous (PV), cranial mesenteric arterial (CMA) and PV-CMA concentrations of PEA and PAA were observed with increase in amount of PEA instilled intraduodenally (i.d.); PAA predominated over PEA, more so in CMA than PV blood. Radioactivity was not recovered from blood following intragastric instillation of PEA. When histamine 1.7 mumol kg-1, i.d., was combined with PEA 1.7 mumol kg-1, i.d., or tyramine 8.5 mumol kg-1, i.d., was combined with PEA 8.5 mumol kg-1, i.d., PV-CMA values for PEA were significantly augmented. Arterial concentrations of PEA were increased 3.5 to 5 fold compared to controls by pretreatment with mebanazine or deprenyl plus clorgyline; arterial concentrations of PAA were reduced. PEA blood concentrations were not significantly altered by clorgyline or deprenyl pretreatment. Infusion of PEA 680, 1020 or 1360 nmol kg-1 min-1 for 20 min into the portal vein raised blood pressure 60 to 100 mmHg (at a PEA concentration of ca, 2 nmol ml-1) but lacked effect on the nictitating membrane despite peak arterial PEA concentrations of 20 nmol ml-1; in cats pretreated with mebanazine or clorgyline plus deprenyl, half-maximum contraction of the nictitating membrane occurred with arterial PEA concentrations of 4.8 to 9 nmol ml-1. In cats pretreated with mebanazine or deprenyl plus clorgyline, half maximum contraction of the nictitating membrane was elicited also by intraduodenal PEA 8.5 mumol kg-1 at arterial PEA concentrations of ca. 2 nmol ml-1, despite lack of effect of PEA 17 mumol kg-1, i.d., in control cats with a peak arterial PEA concentration of 1.8 nmol ml-1. [14C]-PEA and PAA were recovered from liver, kidney, distal small intestine, lung, arterial vessel walls, skeletal muscle, brain, foetus and amniotic liquor, after PEA instilled i.d., overall concentration of PEA exceeding that of PAA except in the kidney. The combined amount of PEA and PAA in kidney was 7 to 20 fold that in other tissues. PEA content of tissues was significantly elevated and that of PAA diminished by pretreatment with deprenyl plus clorgyline, and to a lesser extent after mebanazine.

Animals↗
PubMed1984

Interactions of a non-selective monoamine oxidase inhibitor, phenelzine, with inhibitors of 5-hydroxytryptamine, dopamine or noradrenaline re-uptake.

Interactions of combined antidepressants which occur in man were reproduced in rats pretreated with phenelzine, features elicited including myoclonic phenomena, an augmented lower limb flexor reflex, muscle fasiculation and fatalities, particularly with combinations incorporating 5-hydroxytryptamine (5-HT) re-uptake inhibitors. Combinations of antidepressants included phenelzine with 5-HT re-uptake inhibitors (paroxetine, fluoxetine, clomipramine); with "mixed" re-uptake inhibitors affecting 5-HT and noradrenaline (imipramine, amitriptyline); with noradrenaline re-uptake inhibitors (desipramine, maprotiline, nisoxetine) and with dopamine re-uptake inhibitors (benztropine, nomifensine). Myoclonic phenomena such as forelimb flexor-extensor movements, head and body twitches, occurred in phenelzine pretreated rats after paroxetine, fluoxetine, clomipramine, imipramine, amitriptyline and desipramine. Wet dog shakes, the most intense phenomenon, were obtained only after paroxetine, fluoxetine, clomipramine and imipramine. Myoclonic features were prevented when pretreatment included p-chlorophenylalanine but were unaffected when this incorporated alpha-methyl-p-tyyrosine; there were attenuated by methysergide, cyproheptadine, clozapine or pimozide. The myoclonic phenomena were reproduced by combination of 5-hydroxytryptophan but not L-3,4-dihydroxyphenylalanine with clomipramine. Electrocortical changes observed included 2-4 Hz, 5-8 Hz, large amplitude potentials unrelated to the myoclonic incidents and unaffected by sensory stimulation. Following phenelzine, brain monoamine oxidase (MAO) A inhibition was 99% and that of MAO B, 88%; 5-HT concentration was significantly elevated in the cortex and hypothalamus, as was hypothalamic noradrenaline. Peak and basal tensions of a lower-limb flexor reflex were elevated in phenelzine pretreated spinal rats by fluoxetine, paroxetine, clomipramine and imipramine, effects attenuated by cyproheptadine. Forelimb flexor-extensor movements and body twitches were elicited by fluoxetine and paroxetine in phenelzine pretreated spinal rats in the presence of electrical stimulation of the central stump of a divided posterior tibial nerve. Pressor responses were observed in phenelzine pretreated spinal rats given 5-HT re-uptake inhibitors, "mixed" re-uptake inhibitors and those affecting noradrenaline re-uptake; ECG anomalies occurred in such rats given clomipramine.

Animals↗
PubMed1984

Interactions of non-selective monoamine oxidase inhibitors, tranylcypromine and nialamide, with inhibitors of 5-hydroxytryptamine, dopamine or noradrenaline re-uptake.

Rats pretreated with tranylcypromine and given clomipramine, developed head and body twitches, forelimb flexor-extensor movements and wet dog shakes, phenomena which failed to develop when pretreatment incorporated p-chlorophenylalanine (PCPA) but were unabated when this included alpha-methyl-p-tyrosine (AMPT). Locomotor activity, itself enhanced by tranylcypromine, was further and significantly elevated compared to saline, by clomipramine or imipramine in grouped rats (n = 3) but not in single or paired rats; desipramine lacked such action. This effect of clomipramine was prevented when PCPA was incorporated into the pretreatment and that of imipramine by including PCPA or AMPT. Brain monoamine oxidase (MAO) A inhibition was 92% and that of MAO B, 80%. Cortical hydroxytryptamine (5-HT) and noradrenaline concentrations as well as hypothalamic 5-HT, were significantly elevated by tranylcypromine, as was dopamine in the striatum, nucleus accumbens and tuberculum olfactorium. Hyperthermia developed in tranylcypromine pretreated rats given paroxetine or fluoxetine. Myoclonic phenomena were elicited by paroxetine, fluoxetine, clomipramine or imipramine in nialamide pretreated rats but these were less intense than in rats pretreated with phenelzine or tranylcypromine. Fatalities were fewer than in rats pretreated with tranylcypromine or phenelzine. Brain MAO A inhibition was 92% and that of MAO B, 69%.

Animals↗
PubMed1983

Clinical and experimental aspects of interactions between amine oxidase inhibitors and amine re-uptake inhibitors.

Dangerous and even fatal interactions can occur in man following combinations of antidepressants which include non-selective MAO inhibitors. To ascertain the causation, interactions reproducing the clinical phenomena have been elicited in animals with these combinations, and the mechanisms involved have been explored by various pharmacological strategies; 5-HT re-uptake inhibitors proved especially hazardous in combination. Interactions could, however, be avoided even with the 5-HT re-uptake inhibitors, by combination with relatively selective MAO A or B inhibitors, an approach with potential clinical value.

Animals↗
PubMed1982

Antipodal central effects of apomorphine and dopamine in chickens.

Dopamine, infused into the hypothalamus or injected into the 3rd cerebral ventricle of chickens pretreated with mebanazine, induced behavioural and electrocortical sleep, suppressed motor activity and lowered body temperature and CO2 elimination, effects prevented by phenoxybenzamine but not spiperone. The hypothermic effects of dopamine were intensified by testing chicks below thermoneutrality. Ampomorphine, infused into the hypothalamus, injected into the 3rd cerebral ventricle or given intravenously, evoked behavioural and electrocortical arousal in the intact chicken and in the encéphale isolé preparation. Additionally, pecking, vocalization, increased motor activity and CO2 elimation were elicited; body temperature was elevated in about half the chickens but lowered in the remainder. Chicks tested below thermoneutrality responded with a fall in body temperature to apomorphine, the fall being greatest for those in which apomorphine had hypothermic actions at thermoneutrality. The actions of apomorphine, except on body temperature, were antagonized by spiperone. The effects of apomorphine resembled those of dexamphetamine, but whereas those of the latter were antagonized by less than equimolar dosage of methysergide, the effects of apomorphine were not; spiperone, effective against apomorphine, in equimolar dosage did not prevent the effects of dexamphetamine in 3 of 4 chickens tested.

Animals↗
PubMed1978

Separation of radioactive histamine and some of its metabolites by one-dimensional paper chromatography.

A simple one-dimensional paper chromatograph technique is described for the separation of radioactive histamine and some of its metabolites in blood and tissues. After removal of protein, the supernatant fluid (200 microliter) is subjected to two-stage one-dimensional paper chromatography. This enables large numbers of samples to be chromatographed simultaneously. Using this technique in conjunction with liquid scintillation counting, it was possible to monitor the small amounts (0.02 nCi) of radioactive histamine and its metabolites in serial blood samples.

Animals↗
PubMed1978

Effects of spiperone on self-stimulation and other activities of the Mongolian gerbil.

1 Self-stimulation to lever pressing and capacitance probe touching was obtained in Mongolian gerbils (Meriones unguiculatus) from electrode placements within the medial forebrain bundle. 2 Lever pressing was more sensitive to the decremental effects of a central depressant, pentobarbitone, than capacitance probe touching, suggesting its greater responsiveness to disturbances of motor function. 3 Spiperone (0.005 to 0.05 mg/kg) attenuated capacitance probe touching and lever pressing equally, a finding explained by action on either reward pathways or on the ability to initiate responding. 4 This same dose range of spiperone (0.005 to 0.05 mg/kg) attenuated locomotor activity, whether spontaneous or evoked by non-contingent electrical stimulation, and produced catalepsy. 5 The spiperone-induced attentuation of self-stimulation was not necessarily a result of its action on dopaminergic reward pathways since the effects could equally well be explained by a failure to initiate responding.

Animals↗
PubMed1978

Metabolism and distribution of exogenous histamine in cats.

1 The metabolism and disposition in blood and tissues of exogenous [(14)C]-histamine was examined in cats.2 The principal metabolites in blood of histamine instilled into the small intestine (directly or by transfer from the stomach) and colon were imidazoleacetic acid and t-methylimidazoleacetic acid, being present in approximately equal amounts although in individual cats one or other acid could predominate. Only small amounts of histamine entered the circulation although in two of four cats given the largest dose (82 mumol/kg) large amounts were recovered. The amount of (14)C radioactivity absorbed varied directly with the dose instilled. The chief metabolite in kidney and urine, whether histamine was instilled into the intestine or infused parenterally, was t-methylimidazoleacetic acid. Histamine was not absorbed from the stomach and its metabolism there was negligible.3 In contrast, when histamine was infused into blood leaving the intestine (portal vein) the main metabolite in blood and tissues was t-methylimidazoleacetic acid being found in approximately 5-fold the concentration of imidazoleacetic acid. The small amount of histamine which eluded inactivation/uptake by liver, lungs, heart during the infusion was halved on circulation through the intestine. When histamine was infused into blood supplying the intestine, (cranial mesenteric artery) t-methylimidazoleacetic acid while still the major metabolite in blood was now only 1.4 times the concentration of imidazoleacetic acid. Additionally, the blood concentration of histamine during the infusion exceeded that of the metabolites.4t-Methylimidazoleacetic acid was also the principal metabolite in blood and tissues following histamine infusion into a cannula carrying a replacement venous blood supply to the liver of abdominally eviscerated cats. Imidazoleacetic acid and t-methylhistamine were present in equal concentrations and in one-quarter to one-third that of the methylated acid. The latter was also the principal metabolite following intra-arterial histamine infusion to abdominally eviscerated cats without a hepatic blood supply, although initially t-methylhistamine predominated: a large peak of histamine was present during the infusion period. When additionally the renal vessels were ligated, t-methylhistamine predominated throughout the experiment.5 In conclusion, intraduodenally instilled histamine was metabolized equally by diamine oxidase and imidazole N-methyltransferase (followed by deamination by monoamine oxidase). In contrast, imidazole N-methyltransferase was the principal inactivator of parenterally infused histamine, deamination of t-methylhistamine by monoamine oxidase becoming progressively less efficient with the cumulative exclusion of the intestines, liver and kidney from the circulation.

Abdominal Muscles↗
PubMed1977

Some effects of intravenous prostaglandin E, and endotoxin in young chickens.

1 The effects of intravenous prostaglandin E1 and endotoxin were studied in young chickens (11-17 days old). 2 At a thermoneutral ambient temperature (31 degrees C), intravenous prostaglandin E1, produced behavioural and electrocortical sleep, increased oxygen consumption and, after an initial fall, elevated body temperature. Below thermoneutrality (16 degrees C), the initial hypothermic effect was more marked and oxygen consumption was lowered. 3 The soporific actions of prostaglandin E1 were sufficient to counteract dexamphetamine-induced behavioural and electrocortical arousal and vocalization. 4 Intravenous injection of the O-somatic antigen of Shigella dysenteriae evoked, after a latent period, long lasting hyperthermia. This indicates that in young chicks the blood brain barrier is probably permeable to endotoxins.

Animals↗
PubMed1977

Some effects of prostaglandins E1 and E2 and of endotoxin injected into the hypothalamus of young chicks: dissociation between endotoxin fever and the effects of prostaglandins.

Prostaglandins E1 and E2 elevated body temperature of young chicks when injected into the hypothalamus at thermoneutrality (31 degrees C). In contrast, they lowered body temperature when so injected below thermoneutrality (16degreesC): the relation of the fall in body temperature to increased heat loss and decreased heat production was examined. 2 The above effects below thermoneutrality were potentiated by pretreatment with inhibitors of prostaglandin synthetase and possible reasons for this potentation are given. 3 The O-somatic antigen of Shigella dysenteriae consistently evoked hyperthermia when injected into the hypothalamus, irrespective of whether the chicks were within or below thermoneutrality. 4 Pretreatment with prostaglandin synthetase inhibitors failed to prevent the onset of endotoxin fever; however, duration of the fever, induced by intrahypothalamic injection of the O-somatic antigen of Shigella dysenteriae was reduced. 5 The intrahypothalamic injection, belwo thermoneutrality of prostaglandins E1, E2, noradrenaline, 5-hydroxytryptamine or carbachol reversed endotoxin fever, inducing even substantial falls in body temperature. 6 While the results cast some doubts on the role of prostaglandins of the E series as mediators of endotoxin fever in chicks, they cannot be eliminated as mediators until the significance of the reduction in duration of the pyrexic response by indomethacin and 5,8,11,14-eicosatetraynoic acid, and the degree of synthesis inhibition attained, are known.

5,8,11,14-Eicosatetraynoic Acid↗