Biomedical subjects

Robert M Harris

Publications and source records attributed to Robert M Harris.

6 recordsLinked to original sources

PubMed2006

Total synthesis of (+)-cis-sylvaticin: double oxidative cyclization reactions catalyzed by osmium.

The double oxidative cyclization of dienes is a viable procedure for making complex natural products containing cis-THF units. A double deprotection/double oxidative cyclization strategy using catalytic osmium tetroxide was used to construct the bisheterocyclic core of cis-sylvaticin and ultimately confirm its structure. The natural product was then prepared by a short sequence of reactions that is exceptionally concise: the final route being just 13 linear steps and 19 chemical operations in total.

Catalysis↗

PubMed2006

New osmium-based reagent for the dihydroxylation of alkenes.

The cis dihydroxylation of alkenes is most efficiently accomplished by reaction with osmium tetroxide. Recently, the expense and toxicity of osmium tetroxide have led to a number of attempts to harness alternative osmium-based reagents, including microencapsulation and solid support techniques. We describe here the development of a new nonvolatile, stable, and recoverable osmium-based reagent devised for the stoichiometric cis dihydroxylation of alkenes. Although attempts to make this new dihydroxylation work with catalytic amounts of this reagent were unsuccessful, we did develop a sensitive test for free osmium tetroxide leached from the reagent in situ: this test may well have uses in probing future applications of derivatized osmium reagents.

Alkenes↗

PubMed2005

A methodology for assessing blast protection in explosive ordnance disposal bomb suits.

To reduce human casualties associated with explosive ordnance disposal, a wide range of protective wear has been designed to shield against the blast effects of improvised explosive devices and munitions. In this study, 4 commercially available bomb suits, representing a range of materials and armor masses, were evaluated against 0.227 and 0.567 kg of spherical C-4 explosives to determine the level of protection offered to the head, neck, and thorax. A Hybrid III dummy, an instrumented human surrogate [1], was tested with and without protection from the 4 commercially available bomb suits. 20 tests with the dummy torso mounted to simulate a kneeling position were performed to confirm repeatability and robustness of the dummies, as well as to evaluate the 4 suits. Correlations between injury risk assessments based on past human or animal injury model data and various parameters such as bomb suit mass, projected area, and dummy coverage area were drawn.

Blast Injuries↗

PubMed2004

Blast injury research: modeling injury effects of landmines, bullets, and bombs.

Terrorist blasts and landmine injuries have become more common in the past several decades generating thousands of casualties. Preventive and prognostic measures are limited by the lack of knowledge of these complex events. Previous blast research has focused on primary blast injuries that involve the lung, despite musculoskeletal injuries being the most common. Through the use of instrumented cadavers, Hybrid III test dummies, and other surrogates, unique models of these events have been created. The investigations studied the effectiveness of antimine footwear, forces and injury mechanisms in temporary shelters subjected to blast, modeling of blast-induced glass fragmentation, and helmet deformation and injury potential under ballistic load. Despite blasts being much higher rate events than those seen in automotive blunt trauma, we were able to measure forces and create injury models. We found that antimine footwear will require additional development to be effective. Guidelines for shelter placement have been altered, and tempered glass seems to offer no protection when compared with annealed glass. Although these models are in their nascent phase, the thorough understanding of the biomechanical nature of these blast injuries will assist in developing strategies to reduce injuries and in the creation of forecasting models.

Biomechanical Phenomena↗

PubMed2003

Environmental endocrine disrupters dysregulate estrogen metabolism and Ca2+ homeostasis in fish and mammals via receptor-independent mechanisms.

Xenoestrogen endocrine disrupters (EDs) in the environment are thought to be responsible for a number of examples of sexual dysfunction that have recently been reported in several species. There is growing concern that these compounds may also cause abnormalities of the male reproductive tract and reduced spermatogenesis in man. Whilst some effects of EDs may be receptor-mediated, there is growing evidence that these compounds can exert potent effects in vivo by directly interacting with cellular enzyme targets. Here we report on, and review, the effects of alkylphenols and other EDs on two such enzymes: (1) sulfotransferases, which convert active estrogenic steroids to inactive steroid sulfates; and (2) Ca(2+)-ATPases, which are responsible for maintaining low, physiological, intracellular Ca(2+) concentrations. These enzymes are potently inhibited by EDs in both fish and mammalian species. The increased concentrations of active estrogens and the likely cytotoxic effects of elevated concentrations of intracellular Ca(2+) arising from these effects may underlie some of the endocrine disrupting potential of these widespread industrial pollutants.

Animals↗

PubMed2002

Imaging body armor.

This study examined the feasibility of performing radiographic studies on patients wearing standard-issue body armor. The Kevlar helmet, fragmentation vest, demining suit sleeve, and armor plate were studied with plain film and computed tomography in a simulated casualty situation. We found that the military helmet contains metal screws and metal clips in the headband, but diagnostic computed tomographic images can be obtained. Kevlar, the principal component of soft armor, has favorable photon attenuation characteristics. Plate armor of composite material also did not limit radiographic studies. Therefore, when medically advantageous, patients can be examined radiographically while wearing standard military body armor. Civilian emergency rooms should be aware of these observations because law enforcement officers wear similar protective armor.

Extremities↗