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Biomedical subjects

E S Hawkins

Publications and source records attributed to E S Hawkins.

9 recordsLinked to original sources
PubMed1994

A synthetic route to 3-C-alkyl (or 3-C-phenyl-) 2,3-dideoxy-D-erythro-pentono-1,4-lactones: intermediates in the synthesis of 2(3H)-furanones.

A series of 3-C-alkyl- (and 3-C-phenyl-) 2,3-dideoxy-D-erythro-pentono-1,4-lactones, compounds which are important in the synthesis of modified nucleosides and antibiotic sugars, were synthesized from D-ribonolactone. By a route that proceeded via 5-O-protected D-ribonolactone, 5-O-protected 2,3-dideoxy-D-glycero-pent-2-enono-1,4-lactones were synthesized and reacted with R2CuLi or a complex PhSCu(RMgBr)n to give respectively the 3-C-alkyl or 3-C-phenyl compounds. Details of the preparation of the O-protected intermediates, as well as the selection of the organometallic reagents, are provided.

4-Butyrolactone↗
PubMed1994

Synthesis of some 2-C-alkyl-2,3-dideoxy-alpha,beta-L-glycero-tetrurono-1,4-lactones . Evaluation as antitumor agents.

A series of 3-C-alkyl-2,3-dideoxy-5-O-trityl-D-erythro-pentono-1,4-lactones were detritylated. The resultant free-hydroxy compounds were converted to their respective 2-C-alkyl-2,3-dideoxy-alpha,beta-L-glycero-tetrurono-1,4-lactones (L-sugar numbering) in a one-vessel reaction sequence of (a) conversion of the lactones to their aldonic acid sodium salts, (b) cleavage of the resulting aldonates with sodium metaperiodate, and (c) acidification, followed by acetylation, to give the title compounds. The unsubstituted tetrurono-1,4-lactones were inhibitory toward L1210 leukemia cells at concentrations in the 10(-4) M range.

Animals↗
PubMed1993

Reduction of plantar pressure with the rigid relief orthosis.

The rigid relief orthosis was developed to protect vulnerable sites on the plantar surface of the insensitive foot against reulceration by providing both a nonyielding relief under the healed lesion site and a total contact fit. Clinically, the rigid relief orthosis has been effective in protecting the foot against the trauma induced by the repetitive mechanical stress of walking. This study used both the Hercules and F-Scan pressure transducer systems to measure pressure at the first metatarsal head in three orthotic treatments. Both measurement systems recorded significant reductions in pressure at the first metatarsal head with the rigid relief orthosis, establishing a quantitative rationale explaining its clinical effectiveness. Significant pressure differences were also recorded at the secondary sites of the heel, midfoot, and third metatarsal head.

Adult↗
PubMed1988

8-Ketodeoxycoformycin and 8-ketocoformycin as intermediates in the biosynthesis of 2'-deoxycoformycin and coformycin.

An enzyme has been isolated from cell-free extracts of Streptomyces antibioticus that can catalyze the reduction of 8-ketodeoxycoformycin (8-KetodCF) and 8-ketocoformycin (8-ketoCoF) to the naturally occurring nucleoside analogues 2'-deoxycoformycin (dCF) and coformycin (CoF), respectively. The partially purified reductase requires NADPH as the cofactor and stereospecifically reduces the 8-keto group of both ketonucleoside substrates to a hydroxyl group with the R configuration at C-8. This is the same configuration of the hydroxyl group as that of the dCF and CoF isolated from S. antibioticus. The reduction proceeds at the nucleoside level, and ATP is not required. The reductase is stereospecific for the NADPH cofactor in that it transfers the pro-S but not the pro-R hydrogen from C-4 of NADPH to the 8-keto group. The apparent Km for 8-ketodCF and 8-ketoCoF were 250 and 150 microM, respectively. These in vitro results, which show that 8-ketodCF and 8-ketoCoF may be intermediates in the biosynthesis of dCF and CoF, support and extend our earlier results from in vivo studies which established that adenosine and C-1 of D-ribose are the carbon-nitrogen precursors of dCF. A possible mechanism for the formation of dCF is presented.

Adenosine Deaminase Inhibitors↗
PubMed1988

6- and 8-hydroxy-3,4-dihydro-3-(dipropylamino)-2H-1-benzopyrans. Dopamine agonists with autoreceptor selectivity.

The dopamine agonist profiles of 3,4-dihydro-3-(3-dipropylamino)-2H-1-benzopyran-6- and -8-ol (4 and 5, respectively) were examined. Both 4 and 5 exhibited greater relative affinity for receptors labeled with the dopamine agonist ligand [3H]propylnorapomorphine than for those labeled with the dopamine antagonist ligand [3H]haloperidol. Both compounds attenuated the stimulation of brain dopamine synthesis caused by gamma-butyrolactone (GBL) and decreased the firing rate of substantia nigra dopamine neurons in rats. This profile of activity, together with the ability of the dopamine antagonist haloperidol to reverse the inhibition of dopamine neuronal firing, indicate that both compounds are brain dopamine agonists.

4-Butyrolactone↗
PubMed1988

Pedal manifestations of systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is an autoimmune disease with numerous pedal manifestations. Since pedal manifestations are often its first presentation, it is important that the podiatrist knows how to recognize the disease. This article discusses the manifestations, diagnosis, and treatment of SLE as they relate to podiatry.

Foot Diseases↗
PubMed1987

Biosynthesis of 2'-deoxycoformycin: evidence for ring expansion of the adenine moiety of adenosine to a tetrahydroimidazo[4,5-d][1,3]diazepine system.

2'-Deoxycoformycin (2'-dCF), a nucleoside antitumor agent produced in trace quantities by Streptomyces antibioticus, has been shown in earlier work to originate from the intact carbon-nitrogen framework of adenosine. Additional experiments using 13C and two-dimensional Fourier transform NMR techniques, together with radiolabeling studies, identify the C-1 of D-ribose, and not the tetrahydrofolate "C-1 pool", as the source of the C-7 carbon in the aglycon of 2'-dCF. These results show that the adenine portion of adenosine (or a nucleotide thereof) undergoes a unique ring expansion, by insertion of a -CH2- unit between the N-1 and C-6 of the adenine ring, to furnish the 1,3-diazepine portion of 2'-dCF.

Adenosine↗