Histamine and reflex vasodilatation in the rat.
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Animals↗
Biomedical subjects
M D Adams
Publications and source records attributed to M D Adams.
In vivo fluorine-19 MR imaging: relaxation enhancement with Gd-DTPA.
The lack of a naturally occurring background signal from fluorine in magnetic resonance (MR) imaging makes fluorinated compounds potentially attractive candidates for tissue-specific MR contrast agents. Problems associated with the in vivo use of fluorinated compounds are toxicity, which limits the amount of agent that can be used; multiple resonance lines; and an excessively long T1, which leads to long sequence TRs and consequently long imaging times. Many fluorinated agents also possess complex MR spectra that result in chemical shift artifacts if not corrected. The authors demonstrate the use of an extracellular fluorinated agent with a single MR peak for selective imaging of a brain abscess in an animal model and show that the image signal per unit of acquisition time can be enhanced through the use of a T1 relaxation agent, gadolinium diethylenetriamine-pentaacetic acid (DTPA). Trifluoromethylsulfonate was administered at a fluorine-19 dose of 4 mmol/kg, and fluorine images of the induced abscess were acquired before and after the injection of a standard dose of Gd-DTPA (0.1 mmol/kg); non-section-selected projection images were used. Typical imaging times were less than 5 minutes. The signal enhancement factor achieved was approximately four (4.0 +/- 0.8) with use of a 500/12 (TR msec/TE msec) spin-echo sequence.
Animals↗
Preliminary evaluation of a polyethyleneglycol-stabilized manganese-substituted hydroxylapatite as an intravascular contrast agent for MR angiography.
A blood-persistent particulate paramagnetic contrast agent has been formulated via size stabilization of manganese-substituted hydroxylapatite by a polyethylene glycol (PEG) bearing a terminal diphosphonate. At high PEG surface densities (35-40 mol%), particles with mean diameter 8 +/- 2 nm were obtained. Relaxivities of autoclaved samples (at 20 MHz proton Lamor frequency) were R1 = 18.7 +/- .8 mM-1 sec-1 and R2 = 22.3 +/- .7 mM-1 sec-1. The formulation persisted in rabbit blood with a biphasic clearance profile. Half-lives (with amplitudes in parenthesis) were 4 +/- 1 minutes (55%), and 49 +/- 3 minutes (45%), respectively, for the two phases. A dose of 40 mumol Mn/kg body weight enhanced the signal from rabbit vasculature for more than 45 minutes on MR angiograms. Thus, PEG-modified MnHA particles may find use as T1 agents for MR angiography.
Animals↗
Genome sequence analysis: scientific objectives and practical strategies.
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Human Genome Project↗
synthesis and biological testing of nonionic iodinated x-ray contrast media.
A series of nonionic x-ray contrast media containing novel linkages between the triiodobenzene and polyhydroxy moieties have been prepared and screened against established criteria. Of the coupler groups examined (amide including dipeptide, carbamate, ureido, and ester), amide showed the greatest overall utility in terms of safety, solubility, stability, and ease of synthesis. Acute toxicity, solubility and stability data are summarized for each series. In the CNS, certain compounds were well tolerated and some were devoid of any excitatory effects. Intrathecal tissue irritant effects were also unremarkable. Most agents exhibited relatively high osmolalities, raising questions as to the influence of this factor on the safety of myelographic agents. Intravascularly, nonionic media appear also to offer advantages over classical ionic media. However, nonionic media can exert positive inotropic effects and exhibit high viscosity at higher iodine concentrations. Nevertheless, overall results continue to demonstrate the radiographic potential of nonionic contrast media.
Animals↗
Extended analysis of the region encompassing the PRM1-->PRM2-->TNP2 domain: genomic organization, evolution and gene identification.
The human male haploid expressed protamine 1 (PRM1)-->protamine 2 (PRM2)-->transition protein 2 (TNP2) locus comprises a coordinately regulated multigenic domain. This region of 16p13.13 has been used as a model to address how the organization of genes and genic domains within the human genome may influence tissue specific gene expression. Toward this goal, we have completed an extensive computational and biological analysis of the region encompassing the PRM1-->PRM2-->TNP2 domain. These analyses have revealed the likely genesis of this domain. Interestingly, the SOCS-1 gene and an hnRNPC-class pseudogene lies just 3' of this domain. Regions of nuclear matrix attachment also mark these newly identified genes.
Chromosomal Proteins, Non-Histone↗