Measurement of 227Ac impurity in 225Ac using decay energy spectroscopy.

225Ac is a valuable medical radionuclide for targeted α therapy, but 227Ac is an undesirable byproduct of an accelerator-based synthesis method under investigation. Sufficient detector sensitivity is critical for quantifying the trace impurity of 227Ac, with the 227Ac/225Ac activity ratio predicted to be approximately 0.15% by end-of-bombardment (EOB). Superconducting transition edge sensor (TES) microcalorimeters offer high resolution energy spectroscopy using the normal-to-superconducting phase transition to measure small changes in temperature. By embedding 225Ac production samples in a gold foil thermally coupled to a TES microcalorimeter we can measure the decay energies of the radionuclides embedded with high resolution and 100% detection efficiency. This technique, known as decay energy spectroscopy (DES), collapses several peaks from α decays into single Q-value peaks. In practice there are more complex factors in the interpretation of data using DES, which we will discuss herein. Using this technique we measured the EOB 227Ac impurity to be (0.142 ± 0.005)% for a single production sample. This demonstration has shown that DES is a useful tool for quantitative measurements of complicated spectra.

Sleep duration and weight loss among overweight/obese women enrolled in a behavioral weight loss program.

OBJECTIVE: The purpose of this study was to examine whether baseline sleep duration predicts weight loss outcomes in a randomized controlled trial examining a behavioral weight loss (BWL) intervention among overweight and obese (OW/OB) women with urinary incontinence; and whether participation in the BWL intervention is associated with changes in sleep duration. DESIGN: Longitudinal, clinical intervention study of a 6-month BWL program. SUBJECTS: Three hundred sixteen OW/OB women, with urinary incontinence (age: 30-81 years, body mass index (BMI; 25-50 kg m(-2)) enrolled from July 2004-April 2006. MEASUREMENTS: Measured height and weight, self-report measures of demographics, sleep and physical activity. RESULTS: Neither self-reported total sleep time (TST) nor time in bed (TIB) at baseline significantly predicted weight loss outcomes among OW/OB women in a BWL treatment. BWL treatment was successful regardless of how much subjects reported sleeping at baseline, with an average weight loss of 8.19 kg for OW/OB women receiving BWL treatment, versus a weight loss of 1.44 kg in the control condition. Similarly, changes in weight, BMI and incontinence episodes did not significantly predict changes in sleep duration or TIB across the treatment period. CONCLUSION: Although epidemiological and cross-sectional studies support a relationship between short sleep and increased BMI, the present study found no significant relationship between TST or TIB and weight loss for OW/OB women participating in a BWL treatment.

Incidence of intravascular penetration in transforaminal lumbosacral epidural steroid injections.

STUDY DESIGN: A prospective, observational, human, in vivo study. OBJECTIVES: To evaluate the incidence of vascular penetration during fluoroscopically guided, contrast-enhanced, transforaminal lumbar epidural steroid injections (ESIs) and determine whether a "flash" (blood in the needle hub) or aspiration of blood can be used to predict a vascular injection. SUMMARY OF BACKGROUND DATA: Incorrectly placed, intravascular lumbosacral spinal injections result in systemic medication flow that misses the desired target. No previous studies evaluate the incidence of vascular injections in transforaminal ESIs, nor the ability of flash to predict a vascular injection. METHODS: The incidence of flash or positive blood aspiration and the incidence of fluoroscopically confirmed vascular spread were prospectively observed in 670 patients treated with lumbosacral fluoroscopically guided transforaminal ESIs. Presence of a flash or positive aspiration was documented. Contrast was injected to determine whether the needle tip was intravascular. RESULTS: Seven hundred sixty-one transforaminal ESIs were included. The overall rate of intravascular injections was 11.2%. There was a statistically significant higher rate of intravascular injections (21.3%) noted with transforaminal ESIs performed at S1 (n = 178), compared with those at the lumbar levels (8.1%, n = 583). Using flash or positive blood aspirate to predict intravascular injections was 97.9% specific, but only 44.7% sensitive. CONCLUSIONS: There is a high incidence of intravascular injections in transforaminal ESIs that is significantly increased at S1. Using a flash or blood aspiration to predict an intravascular injection is not sensitive, and therefore a negative flash or aspiration is not reliable. Fluoroscopically guided procedures without contrast confirmation are instilling medications intravascularly and therefore not into the desired epidural location. This finding confirms the need for not only fluoroscopic guidance but also contrast injection instillation in lumbosacral transforaminal ESIs.

Species differences in the interactions of the anticonvulsant milacemide and some analogues with monoamine oxidase-B.

Oxidation of the anticonvulsant drug milacemide [2-n-(pentylamino)acetamide] by monoamine oxidase-B (MAO-B) has been reported to be important in terminating its activity. Comparison of the oxidation of this compound by MAO-B preparations from ox and rat liver showed the former enzyme to have a significantly higher Km value towards this substrate. In keeping with this, the Ki values for milacemide acting as a competitive inhibitor of these enzymes showed it to have a lower affinity for ox liver MAO-B. Comparative studies on the time-dependent inhibition of the two enzymes also showed a lower sensitivity of that from the ox liver. Studies with a series of analogues involving replacement of pentylamino group of milacemide showed marked differences between the sensitivities of the two enzymes. The largest differences were shown by the compound 2(4-(3-chlorobenzoxy)phenethylamino)acetamide which gave IC50 values of 0.051 +/- 0.008 and 4.1 +/- 0.8 microM with the rat and ox enzymes, respectively, when activities were assayed without prior enzyme-inhibitor preincubation. When the enzyme and inhibitor were incubated for 60 min at 37 degrees before assay these values fell to 0.027 +/- 0.002 and 3.5 +/- 0.4 microM, respectively. These marked differences prompted a study of the inhibition of MAO-A and MAO-B from human liver and brain, mouse brain and rat brain as well as MAO-B from ox liver by milacemide and alpha-methylmilacemide. There were no significant differences in the sensitivities of any of the mitochondrial MAO-A preparations studied towards these compounds. However, MAO-B from human brain and liver mitochondrial resembled that from ox liver in being less sensitive to inhibition than the rat and mouse enzymes. Purification of the ox liver MAO-B did not significantly affect its interactions with milacemide and alpha-methylmilacemide. The marked species differences reported here raise questions concerning the validity of rodent model systems, that have frequently been used for assessing the in vivo and in vitro actions of milacemide and its analogues, for the situation in the human.

Interactions of some analogues of the anticonvulsant milacemide with monoamine oxidase.

A series of analogues of the anticonvulsant drug milacemide (2-(n-pentylamino)-acetamide; Compound I) has been synthesized: 2-(benzylamino)acetamide (Compound II), 2-(phenethylamino)acetamide (Compound III), 2-(2-indol-3-yl)-ethylamino acetamide (Compound IV), 2-(2-(5-methoxyindol-3-yl)ethylamino)-acetamide (Compound V), 2-(2(4-chlorobenzamido)-ethylamino)acetamide (Compound VI), 2-(2-benzamidoethylamino)-acetamide (Compound VII) and 2-(4-(3-chlorobenzyloxy)phenethylamino)acetamide (Compound VIII). These compounds involve retention of the aminoacetamide portion of milacemide but replacement of the pentyl moiety with aromatic residues present in the structures of substrates and inhibitors of the monoamine oxidases. All the compounds tested were substrates for ox liver monoamine oxidase-B (MAO-B), producing an aldehyde that could act as a substrate for ox liver aldehyde dehydrogenase and H2O2 as a result of oxidative cleavage which also released glycinamide, although their Michaelis-Menten parameters differed markedly. None showed detectable activity as substrates for rat liver monoamine oxidase-A (MAO-A). Inhibition of the MAO-B by all the compounds except Compounds VIII and IV showed marked time dependence and was at least partly irreversible. There was no apparent change in the inhibition of MAO-A during enzyme-inhibitor preincubation at 37 degrees for 60 min. Compound VIII was a potent reversible inhibitor of both MAO-A and MAO-B (Ki = 2.8 +/- 0.1 and 4.1 +/- 0.8 microM), respectively. Comparison of the inhibitory potencies and the specificity constants of the series of compounds as substrates for MAO-B revealed no simple correlations with their anticonvulsant activities, as measured by their ability to prevent bicuculline-induced convulsions and death in the mouse. These results suggest that neither inhibition of MAO nor oxidative cleavage by this enzyme to yield glycinamide plays the major role in the anticonvulsant action of these compounds.

The interactions of milacemide with monoamine oxidase.

The interactions of the anticonvulsant drug milacemide (2-n-pentylaminoacetamide) with rat liver mitochondrial monoamine oxidases-A and -B have been studied. The compound acts as a substrate for the B-form of the enzyme, with an apparent Km value of 49 +/- 4.7 microM and a Vmax value of 1.1 +/- 0.2 nmol/min/mg. It is also a time-dependent irreversible inhibitor of that enzyme. Any activity of monoamine oxidase-A towards this substrate was too low to allow accurate determinations to be made by either luminometric determination of H2O2 formation or spectrophotometric coupling of aldehyde formation to NAD+ reduction in the presence of aldehyde dehydrogenase. Milacemide was a reversible competitive inhibitor towards monoamine oxidase-A. The inhibitor constant (Ki) was 115 +/- 35 microM indicating a higher affinity than that towards monoamine oxidase-B, which was also competitively inhibited in the absence of enzyme-inhibitor preincubation (Ki = 331 +/- 185 microM). Determination of the formation of H2O2 and the aldehyde product of the oxidative cleavage of milacemide by purified monoamine oxidase-B from ox liver indicated that cleavage resulted solely in the formation of pentanal and glycinamide. There was no evidence for alternative cleavage to pentylamine and oxamaldehyde.

Inhibition of monoamine oxidase by clorgyline analogues.

N-Methyl-N-propargyl-3-(4-phenoxy)phenoxypropylamine, an analogue of the MAO-A-selective irreversible inhibitor clorgyline in which the 2,4-dichloro- substitution in clorgyline was replaced by a 2-H atom and a 4-phenoxy group, has been synthesised and assessed as an inhibitor of monoamine oxidase (MAO). This compound proved to be a time-dependent irreversible inhibitor of both MAO-A and -B. However, unlike clorgyline, it was selective towards MAO-B, both in its initial, non-covalent, binding to the enzyme and as an irreversible inhibitor. In order to assess the influence of side-chain length on inhibitory potency, analogues were synthesised in which the side-chain was reduced to 2 CH2 units (N-methyl-N-propargyl-2- (4-phenoxy)phenoxyethylamine) or increased to 4 CH2 units (N-methyl-N-propargyl-4-(4- phenoxy)phenoxybutylamine). Both these compounds were also time-dependent irreversible inhibitors with selectivity towards MAO-B. In the case of the initial, non-covalent, inhibition all these compounds were competitive inhibitors of MAO-A, with respect to the amine substrate, and the affinity for inhibitor binding increased with carbon chain length. In contrast the compounds were all mixed inhibitors of MAO-B. The competitive element of this inhibition (measured by Kis) was similar for the 2 and 3 carbon-chain compounds but decreased markedly when the chain-length was increased to 4 carbons. The uncompetitive inhibition (measured by Kii) decreased as the carbon chain-length was increased from 2 to 3, but there was no significant further change when the length was increased to 4 carbons. The time-dependent irreversible inhibition (measured as the IC50 values after 60 min enzyme-inhibitor preincubation) showed that the potency towards MAO-A increased when the side-chain length was increased from 2 to 3 carbons but that there was no significant difference between the 3 and 4 carbon-chain compounds. In the case of MAO-B inhibition, the 2 and 3 carbon-chain compounds had similar inhibitory potencies but this increased substantially when the chain length was increased to 4 carbons. The significance of the inhibitory behaviour of these compounds is discussed in terms of the structure-activity relationships of mechanism-based irreversible MAO inhibitors.

A discontinuous luminometric assay for monoamine oxidase.

A simple, sensitive and convenient discontinuous luminometric assay for monoamine oxidase (MAO) is described. It is based on measurement of the light production from the peroxidase-catalysed chemiluminescent oxidation of 5-amino-2,3-dihydro-1,4-phthalazinedione (luminol) by the hydrogen peroxide produced in the MAO reaction. The procedure is suitable for use with a wide range of MAO substrates, although 5-hydroxytryptamine, adrenaline and noradrenaline are too readily oxidized by hydrogen peroxide to be used. A particular advantage of this procedure is that it is applicable to the oxidation of substrates which do not yield products, such as an aldehyde or free ammonia, which form the basis of several alternative substrate-independent assay procedures. The application of the procedure to assay the oxidation of benzylamine, tyramine and 2-n-pentylaminoacetamide (milacemide) by a crude mitochondrial preparation from rat liver and purified ox liver MAO-B is demonstrated.

The de-endothelialized rat carotid arterial graft: a versatile experimental model for the investigation of arterial thrombosis.

A novel model of arterial thrombosis was developed. A mechanical endothelium-denuding injury was created (using a scalpel blade) on harvested, freezer-stored rat carotid arteries. Vessel length of 5 mm. were grafted into the femoral arteries of recipient Sprague-Dawley rats using microvascular anastomotic technique. Patency rates in untreated animals were compared with those in animals receiving systemic aspirin or heparin. The control group patency after 2 hours of flow was 15%, while grafts in aspirin- and heparin-treated animals achieved 35% and 95% patency rates, respectively. Uninjured non-frozen carotid grafts in untreated animals yielded a 95% patency rate, while frozen grafts achieved an 80% patency. Therapeutic levels of aspirin, heparin, and urokinase were confirmed through tail bleeding and whole blood clotting tests, as well as platelet aggregation studies and scanning electron microscopy of the graft lumenal surfaces. A long-term series using syngeneic grafts placed in recipients (Lewis-to-Lewis) and employing systemic heparinization demonstrated maintenance of patency for 4 weeks. Scanning electron microscopy revealed good re-endothelialization, well advanced by one week. Histology confirmed the regrowth of endothelial cells, but showed sparse cellular repopulation of medial and adventitial layers. The mechanical injury model was compared to enzymatic de-endothelialization (using trypsin or collagenase), for which patency rates were similar (10% and 0%, respectively). Trypsin de-endothelialized vessels were tested in vitro for the amount of active trypsin remaining bound to the lumenal surface; no detectable activity was found when trypsin inhibitor was applied following trypsin treatment. The versatility of allowing both in vitro evaluation and in vivo patency assessment demonstrates the uniqueness and value of this new model, offering an avenue toward more direct investigations of surface-mediated thrombotic processes.

Is the oxidation of milacemide by monoamine oxidase a major factor in its anticonvulsant actions?

The anticonvulsant drug milacemide (2-n-pentylaminoacetamide) is known to be oxidized by monoamine oxidase-B to yield glycinamide which then breaks-down to give glycine. It has been postulated that it is this liberation of glycine in the brain that accounts for the anticonvulsant effects. In order to test this hypothesis, and since amines bearing a methyl-group in the alpha-position have been shown to be resistant to oxidation by monoamine oxidase, the effects of milacemide were compared with those of alpha-methyl-milacemide. Although the latter compound was found to be toxic at higher concentrations, it was found to antagonize bicuculline-induced convulsions in mice. When milacemide was administered to mice (0.5 mmol/kg, p.o.) there was a substantial increase in urinary glycinamide excretion. No such increase was observed after the administration of the same dose of alpha-methyl-milacemide. Furthermore, alpha-methyl-milacemide was not oxidized by either monoamine oxidase-A or -B in vitro to any detectable extent, although it was a competitive inhibitor of both forms of the enzyme. The findings that alpha-methyl-milacemide has anticonvulsant properties in the bicuculline test but is not a substrate for monoamine oxidase or a source of urinary glycinamide cast doubt on the importance of the oxidation or milacemide to form glycinamide as a major factor in its anticonvulsant action.

Infant's apnea, bradycardia and tachycardia monitor based on the Z-80 microprocessor.

Home monitoring has been increasingly adopted by pediatricians to help in the prevention of sudden infant death syndrome. The home monitor can be made reliable, easy to operate, inexpensive, and capable of data storage. This can be done by using a microprocessor and a minimum number of integrated circuit chips. Simple real-time algorithm's and digital hardware have been developed to achieve this goal.

Research summary of a scheme to ascertain the availability of speech information in the myoelectric signals of neck and head muscles using surface electrodes.

The availability of speech information in the myoelectric signals (MES) of neck and head muscles was observed during five experiments conducted on two subjects. The MES of four channels, obtained using surface electrodes, was analog amplified, filtered and enhanced prior to digitization. Information was extracted at the rate of 20 points per second per channel using an average magnitude algorithm. The presence of speech related information was statistically verified with a pattern recognition algorithm based on the maximum likelihood algorithm. The results indicated that statistically significant (p = 0.01) information was present and that this scheme might be valuable in the future development of a vocal prosthesis.

Resolution of the isoenzymes of soybean lipoxygenase using isoelectric focusing and chromatofocusing.

Isoelectric focusing in thin-layer polyacrylamide gels has been applied to the analysis of the enzymes involved in the formation and destruction of peroxides in soybeans [Glycine max (L.)], lipoxygenases and peroxidases, respectively. As a result of differences in pH optima for catalytic activity, lipoxygenases were selectively detected by adjusting the pH employed for activity-specific staining. Type-1 lipoxygenase was revealed not only by staining based on the conversion of linoleic acid to hydroperoxide but also by two stains based on the reduction of the hydroperoxide. These methods were found to be suitable for the analysis and characterization of isoenzyme patterns in different soybean cultivars. A substantial difference in the distribution of lipoxygenases maximally active near pH 7 was observed for cultivars Provar and Vickery. A similar degree of separation of the isoenzymes was achieved on a larger scale using chromato-focusing in the pH range 7.4-5.0.

Initial treatment of profound accidental hypothermia.

The performance of inhalation, heating pads, plumbed garment, inhalation + heating pads, inhalation + plumbed garment, and body-to-body heat exchange rewarming were compared to trunk immersion and spontaneous rewarming under laboratory conditions with mildly cooled volunteers. The experiment included 72 rewarmings. Trunk immersion exhibited the smallest afterdrop, shortest recovery period, and most rapid rewarming. Of the therapies suitable for use in the field, small afterdrops were seen with inhalation, inhalation + plumbed garment, inhalation + heating pads, and spontaneous rewarming. The largest afterdrops were seen with the heating pads and plumbed garment. Body-to-body heat exchange was seen to produce somewhat larger afterdrops than spontaneous rewarming. It is concluded that heating pads and plumbed garment should not be used in treatment of profound hypothermia. It is further concluded that, because of the depression in respiratory minute volume accompanying profound hypothermia, the heating pads and plumbed garment in combination with inhalation therapy should not be used. This leaves inhalation therapy alone as the recommended treatment for profound hypothermia in the field.