Quantitative GC determination of sodium triacetoxyborohydride (STAB).

Sodium triacetoxyborohydride (STAB) is a mild, selective, and frequently used reducing agent for reductive amination transformations. STAB has been reported to undergo degradation when exposed to air, often requiring additional sub-stoichiometric reagent charges to drive reactions to completion. We report the development and qualification of a rapid, quantitative GC derivatization method using 3,4-dihydroisoquinoline to enable accurate hydride assay determination of STAB. Assay data generated from this method has been directly compared to a recently published HPLC method using bromosalicaldehyde as the derivatization reagent. The degradation kinetics of STAB have also been further investigated by Raman spectroscopy to demonstrate how exposure of STAB to air can negatively impact the reagent's performance.

[d4U]-spacer-[HI-236] double-drug inhibitors of HIV-1 reverse-transcriptase.

Four double-drug HIV NRTI/NNRTI inhibitors 15a-d of the type [d4U]-spacer-[HI-236] in which the spacer is varied as 1-butynyl (15a), propargyl-1-PEG (15b), propargyl-2-PEG (15c) and propargyl-4-PEG (15d) have been synthesized and biologically evaluated as RT inhibitors against HIV-1. The key step in their synthesis involved a Sonogashira coupling of 5-iodo d4U's benzoate with an alkynylated tethered HI-236 precursor followed by introduction of the HI-236 thiourea functionality. Biological evaluation in both cell-culture (MT-2 cells) as well as using an in vitro RT assay revealed 15a-c to be all more active than d4T. However, overall the results indicate the derivatives are acting as chain-extended NNRTIs in which for 15b-d the nucleoside component is likely situated outside of the pocket but with no evidence for any synergistic double binding between the NRTI and NNRTI sites. This is attributed, in part, to the lack of phosphorylation of the nucleoside component of the double-drug as a result of kinase recognition failure, which is not improved upon with the phosphoramidate of 15d incorporating a 4-PEG spacer.

Design, synthesis, and in vitro testing of alpha-methylacyl-CoA racemase inhibitors.

The enzyme alpha-methylacyl-CoA racemase (AMACR) is overexpressed in prostate, colon, and other cancers and has been partially validated as a potential therapeutic target by siRNA knockdown of the AMACR gene. Analogs of the natural substrate branched chain alpha-methylacyl coenzyme A esters, possessing one or more beta-fluorine atoms, have been synthesized using Wittig, conjugate addition, and asymmetric aldol reactions and found to be reversible competitive inhibitors. Each diastereomer of the previously reported inhibitor ibuprofenoyl-CoA was also tested. The compounds had Ki values of 0.9-20 microM and are the most potent inhibitors yet known. The presence of beta-fluorine on the alpha-methyl group or the acyl chain results in a significant lowering of the Ki value compared with nonfluorinated analogs, and this is attributed to a lowering of the pKa of the alpha-proton, facilitating enolization and binding. Several of the CoA ester inhibitors were formed by incubating the free carboxylic acid precursors with cell free extracts and CoA. alpha-Trifluoromethyltetradecanoic acid, the precursor to the most potent inhibitor, was shown to inhibit growth of cancer cell lines PC3, CWR22 Rv1, and Du145 in a dose-dependent manner and could be related to the expression level of AMACR.

[d4U]-butyne-[HI-236] as a non-cleavable, bifunctional NRTI/NNRTI HIV-1 reverse-transcriptase inhibitor.

The synthesis of bifunctional compound 10 consisting of d4U joined at C-5 to a butynyl spacer attached to HI-236 is reported using a Sonogashira coupling as a key step. As a non-cleavable bifunctional HIV inhibitor incorporating an NRTI with an NNRTI, 10 shows good inhibitory activity (EC(50)=250 nM) against HIV (IIIB) replication in MT-2 cell culture, which is eight times greater than that of d4T and between those of the two component drugs.

Children in side-impact motor vehicle crashes: seating positions and injury mechanisms.

BACKGROUND: This study aimed to describe the injury mechanisms of children involved in side-impact car crashes, particularly as these relate to seating position, and to estimate the danger of the near-side seating position. METHODS: A prospective two-center study of children involved in severe car crashes in Canada was conducted as well as a retrospective cohort study of children involved in crashes reported in the Fatality Analysis Reporting System (FARS) and the National Automotive Sampling System: Crashworthiness Data System (NASS CDS). RESULTS: Children sitting at the side the car was struck (near-side position) sustained severe head, trunk, and limb injuries. Many of these injuries were attributable to direct intrusion, but some occurred without direct damage to the occupant compartment. Center-seat and far-side occupants had severe injuries only when unrestrained. Injury severity scores were higher for children seated on the near side, and this was statistically significant (p = 0.024) The analysis of Fatality Analysis Reporting System data showed that the risk of fatality was higher for children seated in the near-side position than for those in the center-seat position. The fatality risk ratio was 2.53 (95% confidence interval [CI], 2.08-3.07) for restrained children and 1.84 (95% CI, 1.57-2.17) for unrestrained children. Analysis of the NASS-CDS data showed that for restrained children, severe injury (ISS > or = 16) was more common among those on the near side (7 per 1,000 children) than among those in the center seat (2 per 1,000) or on the far-side seat (1 per 1,000) (p < 0.001). CONCLUSIONS: Severe injuries to near-side occupants occurred in both the presence and absence of compartment intrusion. A typical pattern of head, chest, and extremity injury similar to that seen among child pedestrians was observed among near-side child occupants in side-impact crashes. The center seat was statistically safer than the near-side seat, particularly for restrained child occupants. Scene information may be useful to trauma teams for the prediction of injury type and location. Avoiding intrusion and preventing the occupant from striking the vehicle wall are both important to side-impact protection for children. Improvement of the vehicle safety cage may protect against intrusion injuries. Seating two child occupants in inboard seating positions may provide additional protection against intrusion injuries, and also may protect against nonintrusion injuries.