Effects of Nonstarch Genetic Modifications on Starch Structure and Properties.

This paper examines if, in maize, starch structure and starch-dependent properties might be altered by pleiotropic effects arising from genetic modifications that are not directly related to starch synthesis. The molecular structure, specifically the starch chain-length distributions (CLDs), of two maize lines transformed with Bar (bialaphos resistance) and Cry1c genes (an artificial gene, encoding proteinaceous insecticidal δ-endotoxins) were compared to those of their control lines. The two transgenes are responsible for herbicidal resistance and insect tolerance, respectively. The starch CLDs were measured by enzymatic debranching and measuring the molecular weight distributions of the resulting linear chains. It was found that although all the lines had similar amylose contents, the CLDs of both amylopectin and amylose for Cry1c were noticeably different from the others, having more short amylopectin and long amylose chains. These CLDs are known to affect functional properties, and indeed it was found that the Cry1c transgenic lines showed a lower gelatinization temperature and faster digestion rate than the control or Bar lines. However, a slower digestion rate is nutritionally desirable. Thus, pleiotropic effects from genetic modifications can indirectly but significantly affect the starch synthesis pathway and thus change functional properties of significance for human health.

Seeing Floaters: A Case Report and Literature Review of Intraventricular Migration of Silicone Oil Tamponade Material for Retinal Detachment.

BACKGROUND: Intraocular injection of silicone oil is commonly performed during vitrectomy to tamponade the retina in place for treatment of retinal detachment. Although rare, this intravitreal silicone can migrate through the optic nerve and chiasm and enter the cerebral ventricles. CASE DESCRIPTION: Here we present a case report of a patient presenting with headache and intraventricular hyperdensities on a computed tomography (CT) scan, raising a concern for intraventricular hemorrhage. However, the intraventricular hyperdensities were in a nondependent location and moved to a new nondependent location when repeat imaging was performed with the patient in the prone position. We provide a literature review of this phenomenon and discuss the relevant CT and magnetic resonance imaging findings. CONCLUSIONS: Intraocular silicone can rarely migrate into the cerebral ventricular system. Careful review of the clinical history and imaging findings can help distinguish this from other, more dangerous intracranial pathologies.

Improving human health through understanding the complex structure of glucose polymers.

Two highly branched glucose polymers with similar structures--starch and glycogen--have important relations to human health. Slowly digestible and resistant starches have desirable health benefits, including the prevention and alleviation of metabolic diseases and prevention of colon cancer. Glycogen is important in regulating the use of glucose in the body, and diabetic subjects have an anomaly in their glycogen structure compared with that in healthy subjects. This paper reviews the biosynthesis-structure-property relations of these polymers, showing that polymer characterization produces knowledge which can be useful in producing healthier foods and new drug targets aimed at improving glucose storage in diabetic patients. Examples include mathematical modeling to design starch with better nutritional values, the effects of amylose fine structures on starch digestibility, the structure of slowly digested starch collected from in vitro and in vivo digestion, and the mechanism of the formation of glycogen α particles from ß particles in healthy subjects. A new method to overcome a current problem in the structural characterization of these polymers using field-flow fractionation is also given, through a technique to calibrate evaporative light scattering detection with starch.