In vivo specific binding of [3H]1-nicotine in the mouse brain

[3H] 1-Nicotine was used as a receptor ligand in the intact mouse. It was injected i.v., and radioactivity in brain regions was assayed. Nonspecific binding was estimated by pretreatment with unlabelled 1-nicotine. Radioactivity entered the brain rapidly, was heterogeneously distributed, and declined after 5 min. Estimated specific binding was highest in the medial and posterior cortex, midbrain, thalamus/hypothalamus and medulla/pons; intermediate in the cerebellum, caudate/putamen, frontal and frontoparietal cortex; and lowest in the hippocampus and olfactory bulb. Autoradiography showed similar patterns. Coinjection of unlabelled 1-nicotine reduced specific binding so that it approached estimated nonspecific binding. Nicotinic agonists reduced radioactivity in the thalamus/hypothalamus, but nicotinic antagonists were less active. Non-nicotinic drugs did not reduce brain radioactivity. The results suggest that radiolabelled nicotine may be used for in vivo receptor studies despite problems in estimating nonspecific binding.     

Coliphage and indigenous phage in Mamala Bay, Oahu, Hawaii.

Public concern over the discharge of primarily treated sewage by two offshore outfalls in Mamala Bay, Oahu, prompted a multidisciplinary study to determine the impact of such activities on the water quality in the bay and at adjacent recreational beaches. As part of this study, we determined the abundance of coliphage as an indicator of fecal pollution along with total viral direct counts and phages infective for Vibrio parahaemoltyicus 16 at stations in Mamala Bay in four quarterly samplings over 13 months. Coliphage (< 1 to 1.2 x 10(3)/liter) were found during each quarterly sampling along an offshore transect to the Sand Island waste treatment facility outfall. The nonpoint coastal stations (Pearl Harbor, Ala Wai Canal, and Ke'ehi Lagoon) had high levels of coliphage during the storm event sampling in February 1994 but much lower levels or none when sampled during dry weather. Coliphage were absent at all samplings at Waikiki Beach and at the control station off Diamond Head. Viral direct counts in eutrophic coastal stations (Pearl Harbor, Ke'ehi Lagoon, Ala Moana Beach, and Ala Wai canal) averaged 10(9)/liter, while counts at offshore stations ranged from 9 x 10(7) to 1 x 10(9) viruses/liter, values similar to those for other marine environments. Vibriophage were found mainly in eutrophic coastal environments (Ala Wai Canal, Pearl Harbor, and Ke'ehi Lagoon) and at the Sand Island Transect stations D1 and D2. The greatest abundance was found during the storm event (February 1994) sampling. These results suggest that the Sand Island outfall influenced the water quality of the immediate surrounding waters but had little effect on the quality of the recreational beaches. Nonpoint discharge sources appeared to be more important in the distribution of fecal indicators in the coastal zone.     

Protein NMR spin trapping with [methyl-13C(3)]-MNP: application to the tyrosyl radical of equine myoglobin.

Direct spin trapping studies of protein radical adducts are limited as a consequence of the long rotational correlation times and consequent broadening of the ESR resonances. It can be difficult to determine both the nature and number of adduct species present. NMR detection of reduced spin adducts represents an alternate approach which, however, is subject to the limitations of lower sensitivity and a limited capability for isolating the resonances arising from the reduced adduct from other chemistry involving the spin trap. In the present study, we have utilized [methyl-13C(3)]-MNP for the detection and analysis of tyrosyl spin adducts formed as a result of exposure of equine myoglobin to hydrogen peroxide. The methyl-13C label allows high detection sensitivity in two dimensions, narrow line widths and most significantly, removal by dialysis of unreacted spin trap as well as any nonprotein derivatives that may form. For equine myoglobin, it is found that adduct formation involves a single residue-Tyr-103 and further that adduct formation occurs at the C-3 carbon of the amino acid. HMQC-NOESY experiments further revealed the proximity of the labeled methyl groups to both the three aromatic tyrosyl protons as well as the aromatic protons of the nearby Phe-106 residue.