Investigation of gamma radiation effect on the anion exchange resin Amberlite IRA-400 in hydroxide form by Fourier transformed infrared and 13C nuclear magnetic resonance spectroscopies.

Radiation-induced decomposition of the anion exchange resin Amberlite IRA-400 in hydroxide form by gamma radiolysis has been studied under different irradiation doses and irradiation atmospheres. In this work, we focused on the degradation of the solid part of the resin by Fourier transformed infrared (FTIR) and (13)C nuclear magnetic resonance (NMR) spectroscopies associated with chemometric treatments. FTIR and (13)C NMR techniques showed that only -CH(2)N(+)(CH(3))(3) groups were detached from the resin whereas the polystyrene divinylbenzene backbone remains intact. The quaternary ammonium groups were replaced by amine or carbonyl groups according to the irradiation atmosphere (with or without water or oxygen). Principal components analysis (PCA) was used to classify the degraded resins according to their irradiation conditions by separating the effect of the dose or the environment. The PCA loadings have shown spectral regions which discriminate the irradiated resins whereas SIMPLe-to-use Interactive Self-modeling Mixture Analysis (SIMPLISMA) allows to identify families of component characterizing the chemical structure of resins and estimate their relative contributions according to the irradiation atmospheres.

Impact of troponin T determinations on hospital resource utilization and costs in the evaluation of patients with suspected myocardial ischemia.

The evaluation and triage of patients with suspected myocardial ischemia in the emergency department remains challenging and costly. Previous studies of cardiac troponins have focused predominantly on patients with chest pain and have not randomized patients to different diagnostic strategies. Eight hundred fifty-six patients with suspected myocardial ischemia were prospectively randomized to receive a standard evaluation, including serial electrocardiographic and creatine phosphokinase-MB determinations (controls) or a standard evaluation with the addition of serial troponin T determinations (troponin group). The primary end points were length of stay and hospital charges. Significant reductions in length of hospital stay were seen in troponin T patients both with (3.6 vs 4.7 days; p = 0.01) and without (1.2 vs 1.6 days; p = 0.03) acute coronary syndromes compared with controls. Total hospital charges were reduced in a similar fashion in troponin patients with and without acute coronary syndromes ($15,004 vs $19,202; p = 0.01, and $4,487 vs $6,187; p = 0.17, respectively) compared with controls. Troponin patients without acute coronary syndromes had fewer hospital admissions (25% vs 31%; p = 0.04), whereas troponin patients with acute coronary syndromes had shorter telemetry and coronary care unit lengths of stay (3.5 vs 4.5 days; p = 0.03) compared with controls. Thus, utilization of troponin T in a broad spectrum of emergency department patients with suspected myocardial ischemia improves hospital resource utilization and reduces costs.

Chloramine-T in radiolabeling techniques. IV. Penta-O-acetyl-N-chloro-N-methylglucamine as an oxidizing agent in radiolabelling techniques.

Chloramine-T (CAT) is commonly used in radiolabeling of bioactive molecules by halogenation. CAT is used to release radioactive elemental iodine by oxidation of its salts. Unfortunately, CAT is a strong oxidizing agent and can cause significant damage to peptides and proteins. This may lower the yield of the iodination reaction and may produce undesirable side products. Recently, it was found that the in situ formation of N-chlorosecondary amines, by the addition of secondary amines to CAT prior to exposure to the substrate, can reduce the oxidative damage caused by CAT. To simplify the method, we prepared penta-O-acetyl-N-chloro-N-methylglucamine (NCMGE) as a solid N-chlorosecondary amine. The chemical reactivity of NCMGE toward a model amino acid, 1-aminocyclohexane carboxylic acid, was compared with that of chloramine-T. In the presence of the model amino acid, CAT lost all its chlorine titer within 60 min while NCMGE retained 99% of its chlorine titer. NCMGE was compared to CAT for the iodination of l-tyrosine and leucine enkephalin. For both substrates, the NCMGE method produced larger or equal yields of the monoiodo and diiodo products and less decomposition. It is proposed that the method employing NCMGE to release diatomic iodine is more convenient and efficient for radiolabeling peptides and proteins than currently used methods.

Enhancement of the systemic and CNS specific delivery of L-dopa by the nasal administration of its water soluble prodrugs.

PURPOSE: To study the utility of the nasal route for the systemic delivery of L-dopa using water soluble prodrugs of L-dopa and to examine if this delivery method will result in preferential delivery to the CNS. METHODS: Several alkyl ester prodrugs of L-dopa were prepared and their physicochemical properties were determined. In vitro hydrolysis rate constants in buffer, rat plasma, rat brain homogenate, rat CSF, and rat nasal berfusate were determined by HPLC. In vivo nasal experiments were carried out in rats. Levels of L-dopa and dopamine in plasma, CSF, and olfactory bulb were determined using HPLC method with electrochemical detection. RESULTS: All the prodrugs showed improved solubility and lipophilicity with relatively fast in vitro conversion in rat plasma. Absorption was fast following nasal delivery of the prodrugs with bioavailability around 90%. Dopamine plasma levels did not change significantly following nasal administration of the butyl ester prodrug. Olfactory bulb and CSF L-dopa concentration were higher following nasal delivery of the butyl ester prodrug compared to an equivalent intravenous dose. CONCLUSIONS: Utilization of water soluble prodrugs of L-dopa via the nasal route in the treatment of Parkinson's disease may have therapeutic advantages such as improved bioavailability, decreased side effects, and potentially enhanced CNS delivery.

In vitro effects of sildenafil and phentolamine, drugs used for erectile dysfunction, on human sperm motility.

OBJECTIVE: The aim of this study was to determine the effects of sildenafil and phentolamine on sperm motility in vitro. STUDY DESIGN: Semen or washed sperm was mixed with various doses of sildenafil or phentolamine and analyzed for motility during a 30-minute period. The pH was measured for each of the samples tested. Statistical analyses were performed with analysis of variance. RESULTS: A 200-microg/mL dose of sildenafil had no effect on sperm motility. However, the highest dose (2000 microg/mL) significantly reduced motility by about 50%. The pH was reduced in this high-dose sample. The lowest dose of phentolamine (20 microg/mL) had no effect, whereas a dose of 200 microg/mL resulted in a significant reduction in sperm motility. The highest dose (2000 microg/mL) stopped virtually all sperm from moving. CONCLUSION: This study demonstrated a direct dose-related effect of phentolamine on reducing sperm motility. Only the highest dose of sildenafil had an effect, which may have been caused by a decline in pH.

Chloramine-T in radiolabeling techniques. III. Radioiodination of biomolecules containing thioether groups.

A previously reported method for iodination of the tyrosine moiety of oxidation-sensitive biomolecules was found to cause unacceptable damage to biomolecules containing thiols and thioether groups. This was due to the oxidation of the sulfur-containing residues by molecular iodine (I(2)). To selectively iodinate the tyrosine moiety with minimum oxidation to the sulfur functionality, studies of the kinetics of the reactions between I-(3) and various amino acids and small peptides at various pH values in phosphate buffer were undertaken. Within the pH range studied (5.5-8.2), the results showed that the iodination reaction is strongly catalyzed by hydroxide ions, whereas the oxidation of the sulfur group was insensitive to pH. The results also showed that both reactions are strongly catalyzed by HPO-(4) ion. In a complex molecule, such as methionine-enkephalin, oxidation of the methionine residue (undesirable reaction) proceeds in parallel with iodination of the tyrosine residue (desirable reaction). If such a molecule was iodinated in 0.01 M phosphate buffer at pH values above 7.5, the iodination reaction would proceed much more rapidly than the oxidation reaction, resulting in a high yield of iodinated substrate with little oxidative damage.

The delayed effects and the basal follicle numbers developed by females of Culex pipiens L. Emerged from treatments of larvae with partially-lethal concentrations of Altosid and Dimilin.

The possible juvenilizing effects of Dimilin and Altosid against larvae of Culex pipiens L. were studied. Apart from delayed lethal action, possible effect on the mean number of basal follicles developed per female has been considered. A baseline exposure was found which caused only low mortalities of the early 4th larval instar. Results showed a correlation between the overall deaths during development and the sex ratio. Higher mortality increases the proportion of females. Treatments with 0.00001, 0.0001 and 0.001 ppm Dimilin caused 9.6%, 33.6% and 18.6% increase in the mean basal follicle numbers developed per female, respectively. In the case of Altosid, these levels of increase were 23.1%, 26.5% and 23.8%, respectively, after treatments with the same concentrations.