Development of Natural Multifunctional Cosmetic Ingredients Using a Biotechnological Approach

Carbohydrates have a major role in the cosmetic industry due to their thickening properties and water holding capacity. Various carbohydrates like dextran, xanthan gum, carrageen and levan are presently being used in the preparation of cosmetics. Among these, levan also proved to have some immunobeneficiary properties. Carbohydrates with multi-functionality would help create ‘healthy’ cosmetics. Polysaccharides from higher basidiomycetes are attracting the attention of researchers due to their immunomodulatory properties. This project aims to develop multifunctional polysaccharides from Grifola frondosa for use in cosmetic formulations

Causes of Abnormal Ca2+ Transients in Guinea Pig Pathophysiological Ventricular Muscle Revealed by Ca2+ and Action Potential Imaging at Cellular Level

BACKGROUND: Abnormal Ca(2+) transients are often observed in heart muscles under a variety of pathophysiological conditions including ventricular tachycardia. To clarify whether these abnormal Ca(2+) transients can be attributed to abnormal action potential generation or abnormal Ca(2+) handling/excitation-contraction (EC) coupling, we developed a procedure to determine Ca(2+) and action potential signals at the cellular level in isolated heart tissues. METHODOLOGY/PRINCIPAL FINDINGS: After loading ventricular papillary muscle with rhod-2 and di-4-ANEPPS, mono-wavelength fluorescence images from rhod-2 and ratiometric images of two wavelengths of emission from di-4-ANEPPS were sequentially obtained. To mimic the ventricular tachycardia, the ventricular muscles were field-stimulated in non-flowing Krebs solution which elicited abnormal Ca(2+) transients. For the failed and alternating Ca(2+) transient generation, there were two types of causes, i.e., failed or abnormal action potential generation and abnormal EC coupling. In cells showing delayed initiation of Ca(2+) transients with field stimulation, action potential onset was delayed and the rate of rise was slower than in healthy cells. Similar delayed onset was also observed in the presence of heptanol, an inhibitor of gap junction channels but having a non-specific channel blocking effect. A Na(+) channel blocker, on the other hand, reduced the rate of rise of the action potentials but did not result in desynchronization of the action potentials. The delayed onset of action potentials can be explained primarily by impaired gap junctions and partly by Na(+) channel inactivation. CONCLUSIONS/SIGNIFICANCE: Our results indicate that there are multiple patterns for the causes of abnormal Ca(2+) signals and that our methods are useful for investigating the physiology and pathophysiology of heart muscle

Optical imaging of arrhythmias in the cardiomyocyte monolayer.

In recent years, cultured cardiac cell monolayers have become a contemporary experimental preparation for the study of fundamental mechanisms that underlie normal and pathologic electrophysiology at the tissue level. Ion channels and gap junctions in the cardiomyocyte monolayer may be modulated using drugs that suppress or enhance certain channels/junctions, or by genetic silencing or overexpression. The cardiomyocyte monolayer is particularly well suited for studies of functional electrophysiologic properties of mixtures of cardiac and noncardiac cells (eg, myofibroblasts), which otherwise would be difficult to investigate. Optical mapping of monolayers has provided insight into mechanisms that can set the stage for arrhythmias, such as unidirectional conduction block, gap junction uncoupling, ischemia, alternans, and anisotropy, and continues to enhance our understanding of basic electrophysiologic mechanisms

Contrasting effects of ischemia on the kinetics of membrane voltage and intracellular calcium transient underlie electrical alternans.

Repolarization alternans has been considered a strong marker of electrical instability. The objective of this study was to investigate the hypothesis that ischemia-induced contrasting effects on the kinetics of membrane voltage and intracellular calcium transient (Ca(i)T) can explain the vulnerability of the ischemic heart to repolarization alternans. Ischemia-induced changes in action potential (AP) and Ca(i)T resulting in alternans were investigated in perfused Langendorff guinea pig hearts subjected to 10-15 min of global no-flow ischemia followed by 10-15 min of reperfusion. The heart was stained with 100 microl of rhod-2 AM and 25 microl of RH-237, and AP and Ca(i)T were simultaneously recorded with an optical mapping system of two 16 x 16 photodiode arrays. Ischemia was associated with shortening of AP duration (D) but delayed upstroke, broadening of peak, and slowed decay of Ca(i)T resulting in a significant increase of Ca(i)T-D. The changes in APD were spatially heterogeneous in contrast to a more spatially homogeneous lengthening of Ca(i)T-D. Ca(i)T alternans could be consistently induced with the introduction of a shorter cycle when the upstroke of the AP occurred before complete relaxation of the previous Ca(i)T and generated a reduced Ca(i)T. However, alternans of Ca(i)T was not necessarily associated with alternans of APD, and this was correlated with the degree of spatially heterogeneous shortening of APD. Sites with less shortening of APD developed alternans of both Ca(i)T and APD, whereas sites with greater shortening of APD could develop a similar degree of Ca(i)T alternans but slight or no APD alternans. This resulted in significant spatial dispersion of APD. The study shows that the contrasting effects of ischemia on the duration of AP and Ca(i)T and, in particular, on their spatial distribution explain the vulnerability of ischemic heart to alternans and the increased dispersion of repolarization during alternans

The kinetics of spontaneous calcium oscillations and arrhythmogenesis in the in vivo heart during ischemia/reperfusion.

BACKGROUND: The correlation between spontaneous calcium oscillations (S-CaOs) and arrhythmogenesis has been investigated in a number of theoretical and experimental in vitro models. There is an obvious lack of studies that directly investigate how the kinetics of S-CaOs correlates with a specific arrhythmia in the in vivo heart. OBJECTIVES: The purpose of the study is to investigate the correlation between the kinetics of S-CaOs and arrhythmogenesis in the intact heart using an experimental model of ischemia/reperfusion (I/R). METHODS: Perfused Langendorff guinea pig (GP) hearts were subjected to global I/R (10-15 minutes/10-15 minutes). The heart was stained with a voltage-sensitive dye (RH237) and loaded with a Ca2+ indicator (Rhod-2 AM). Membrane voltage (Vm) and intracellular calcium transient (Ca(i)T) were simultaneously recorded with an optical mapping system of two 16 x 16 photodiode arrays. S-CaOs were considered to arise from a localized focal site within the mapped surface when these preceded the associated membrane depolarizations by 2-15 ms. RESULTS: In 135 episodes of ventricular arrhythmias from 28 different GP experiments, 23 were linked to S-CaOs that were considered to arise from or close to the mapped epicardial window. Self-limited or sustained S-CaOs had a cycle length of 130-430 ms and could trigger propagated ventricular depolarizations. Self-limited S-CaOs that followed the basic beat action potential (AP)/Ca(i)T closely resembled phase 3 early afterdepolarizations. Fast S-CaOs could remain confined to a localized site (concealed) or exhibit varying conduction patterns. This could manifest as (1) an isolated premature beat (PB), bigeminal, or trigeminal rhythm; (2) ventricular tachycardia (VT) when a regular 2:1 conduction from the focal site develops; or (3) ventricular fibrillation (VF) when a complex conduction pattern results in wave break and reentrant excitation. CONCLUSIONS: The study examined, for the first time in the intact heart, the correlation between the kinetics of focal S-CaOs during I/R and arrhythmogenesis. S-CaOs may remain concealed or manifest as PBs, VT, or VF. A "benign looking" PB during I/R may represent "the tip of the iceberg" of an underlying potentially serious arrhythmic mechanism