Collision-induced 1st overtone infrared absorption band of deuterium.

The collision-induced 1st overtone infrared absorption band of deuterium was observed at room temperature. The band was studied in the pure gas and in binary mixtures with argon and nitrogen at a path length of 194.3 cm at pressures up to 800 atm. The observed absorption profiles of the band do not show any splitting of the Q branch and this indicates that the contribution of the short-range overlap forces to the intensity of the band is negligible. The enhancement absorption profiles of D₂-AR mixtures show only single-transition quadrupolar lines. But the enhancement profiles of D₂-N₂ mixtures, in addition, show the double transitions Q₂(J) of D₂ + S₀(J) of N₂, and double vibrational transitions Q₁(J) of D₂ + Q₁(J) of N₂ which occur on the low frequency side of the pure overtone band. Major contribution to the intensity of the absorption profiles of pure deuterium comes from the double transitions Q₂(J) + S₀(J) and Q₁(J) + Q₁(J) in the colliding pairs of D₂ molecules. Integrated absorption coefficients were measured and binary and ternary absorption coefficients were derived. -- The observed enhancement absorption profiles of D₂-Ar and D₂-N₂ were analyzed by a computational procedure into their component lines to yield values of the half widths δs. The analysis of the profiles of D₂-Ar confirmed the fact that the contribution of the overlap forces to the intensity of the band is negligible. From the analysis of the pure overtone profiles of D₂-N₂, the contribution of the double transitions, Q₂(J) of D₂ + S₀(J) of N₂, to the intensity of the band was estimated. The quadrupole moment of the nitrogen molecule was obtained as 1.14 ea²₀ from the ratio of the binary absorption coefficients of the band due to single and double transitions

Mixture of American ginseng extract, ginkgo biloba extract and St. John's wort extract enhances the survival of axotomized retinal ganglion cells

American ginseng (AG) saponins and Ginkgo biloba (GB) extract were shown to exhibit neuroprotective effect against ischemic injury. St. John’s wort (SJW) extract has also been shown recently to have free radical scavenging ability. GB, AG and SJW could therefore offer neuroprotection in a model of optic nerve (ON) transection, where recent evidence implicates the involvement of free radicals in the delayed death of axotomized retinal ganglion cells (RGCs). Transection of the ON 1.5mm from the optic disc was performed on adult hamsters. Starting on the day of operation, the animals received daily oral administration for 7 days of: (1) vehicle (0.01M PBS), (2) GB extract (2, 6 or 12 mg), (3) AG extract (10, 20 or 30mg), (4) SJW extract (10, 20 or 30mg), (5) 30mg of AD-FX, a mixture consisted of 80% AG and 20% GB extracts by weight or (6) 30mg of Menta-FX, a mixture composed of 30.8% AG, 7.7% GB and 61.5% SJW extracts by weight. AD-FX and Menta-FX were purchased from CV Technologies, Canada. RGCs survival 7 days post axotomy was quantified by applying 6% FluoroGold to the transected ON to retrogradely label the surviving RGCs 2 days before the animals were killed. The retinae were dissected and the number of fluorescent labeled RGCs was counted. We found that only treatment with Menta-FX can significantly augment the number of surviving RGCs 7 days after axotomy (p<0.01, one way ANOVA). We therefore showed for the first time that a mixture of GB, AG and SJW extracts, but not each of the extracts alone, can significantly enhance axotomized RGCs survival 7 days after ON transection. Supported by Research Grants from the University of Hong Kon

Regeneration of axotomized retinal ganglion cells is promoted by a mixture of american ginseng extract, ginkgo biloba extract and St. John's wort extract

It has been shown that attachment of a peripheral nerve (PN) graft to the transected optic nerve (ON) stump can markedly increase both the number of surviving and regenerating retinal ganglion cells (RGCs). We recently observed that a mixture of American ginseng (AG), ginkgo biloba (GB) and St. John’s wort (SJW) extracts, can increase viability of axotomized RGCs. We therefore examined the effects of different mixtures of AG, GB and SJW extracts on long distance regeneration of RGCs into a PN graft. ON was transected at 0.5 mm from the optic disc. A 1-cm segment of an autologous sciatic nerve was sutured onto the proximal ocular stump. Animals then received daily oral administration of: (1) vehicle (0.01M PBS); (2) 30mg of AG extract; (3) 30mg of AD-FX, a mixture of 80% AG and 20% GB extracts by weight or (4) 30mg of Menta-FX, a mixture of 30.8% AG, 7.7% GB and 61.5% SJW extracts by weight, for 21 days starting on the day of operation. Standardized batches of AD-FX and Menta-FX were purchased from CV Technologies, Canada. The number of regenerating RGCs 21 days after grafting was determined by injecting 6% FluoroGold into the PN graft 3 days before the animals were killed. The retinae were dissected and the number of fluorescent labeled RGCs was counted. We found that only treatment with Menta-FX significantly promoted regeneration of axotomized RGCs, inducing an 87% increase in the number of regenerating RGCs (p<0.05, one way ANOVA). We therefore showed for the first time that a mixture of AG, GB and SJW extracts can significantly augment regeneration of axotomized RGCs. Supported by Research grants from the University of Hong Kon

Endogenous Anti-apoptotic Mechanism in Axotomized Retinal Ganglion Cells: the Involvement of Elevated Akt Phosphorylation

Purpose:We have previously shown that axotomy induced an early release of cytochrome c in axotomized retinal ganglion cells (RGCs) at 1 day post-axotomy (dpa). Interestingly, activation of caspase-9, caspase-3 and nuclear fragmentation were not observed in axotomized RGCs until 3 dpa. We hypothesize that endogenous neuroprotective pathways exist to temporarily halt the progress of apoptosis at a site downstream of cytochrome c release. Methods:Unilateral optic nerve transection 1.5 mm from the optic disc was performed on adult hamster. Operated animals were sacrificed at various time-points after axotomy to investigate the levels of phospho-Akt (Ser 473) in axotomized retinas using western blotting. Alternatively, the operated eyes were injected intravitreally with wortmannin, an inhibitor of PI3K, at 0 and 1 dpa. Animals were sacrificed at 2 dpa to examine the effect of wortmannin injections on phospho-Akt levels, caspase-3 and -9 activation and nuclear fragmentation in axotomized retinas. Results:We found that axotomy induced a rapid but transient increase in Akt phosphorylation in axotomized retinas. Akt activation markedly increased as early as 3 hours post-axotomy and returned to control level at 3 dpa, coinciding with the onset of caspase activation and RGC loss. In addition, attenuating the increase in Akt phosphorylation following axotomy by intravitreal injections of wortmannin induced the presence of activated caspase-3 and -9-positive apoptotic cells in the ganglion cell layer. Conclusion:Our data suggest that axotomy resulted in an increase in Akt phosphorylation, which delayed the onset of apoptotic machinery downstream of cytochrome c release by inhibiting the activation of caspase-9 or -3. Akt may hence serve as an endogenous neuroprotective pathway to limit RGC death following axotomy

Effects of heat-moisture and alkali treatment on the enzymatic hydrolysis of porous sago (Metroxylon sagu) starch

Pretreatment(s) of heat-moisture treatment (HMT) and alkali treatment was tested for the enzymatic hydrolysis of sago (Metroxylon sagu) starch. HMT was undergone by autoclaving the sago starch at 120°C for 60 min. While sodium hydroxide pellets (0.60% [w/w starch dry basis (d.b.)] to 50 g of sago starch) were applied as the alkali treatment. Dual pretreatments were also evaluated. The dextrose equivalent values of porous starch with alkali pretreatment (31%), HMT (37%), and dual pretreatments (42%) were significantly higher than those of non-pretreated porous sago starch (21%). Greater porosity of pretreated starch granules (0.91–5.19 µm) was also obtained. The thermal properties (gelatinization temperature) of porous starch with pretreatments were improved compared to the non-pretreated porous sago starch. In addition, the pretreatment(s) also improved the oil adsorption capacity of the porous starch. Dual pretreatments were an efficient way to facilitate enzymatic hydrolysis in preparing porous sago starch