Enhanced phenol degradation by immobilized Acinetobacter sp. strain AQ5NOL 1

A locally isolated Acinetobacter sp. Strain AQ5NOL 1 was encapsulated in gellan gum and its ability to degrade phenol was compared with the free cells. Optimal phenol degradation was achieved at gellan gum concentration of 0.75% (w/v), bead size of 3 mm diameter (estimated surface area of 28.26 mm²) and bead number of 300 per 100 ml medium. At phenol concentration of 100 mg l⁻¹, both free and immobilized bacteria exhibited similar rates of phenol degradation but at higher phenol concentrations, the immobilized bacteria exhibited a higher rate of degradation of phenol. The immobilized cells completely degrade phenol within 108, 216 and 240 h at 1,100, 1,500 and 1,900 mg l⁻¹ phenol, respectively, whereas free cells took 240 h to completely degrade phenol at 1,100 mg l⁻¹. However, the free cells were unable to completely degrade phenol at higher concentrations. Overall, the rates of phenol degradation by both immobilized and free bacteria decreased gradually as the phenol concentration was increased. The immobilized cells showed no loss in phenol degrading activity after being used repeatedly for 45 cycles of 18 h cycle. However, phenol degrading activity of the immobilized bacteria experienced 10 and 38% losses after the 46 and 47th cycles, respectively. The study has shown an increased efficiency of phenol degradation when the cells are encapsulated in gellan gum.     

Enhanced butanol production by optimization of medium parameters using Clostridium acetobutylicum YM1

A new isolate of the solvent-producing Clostridium acetobutylicum YM1 was used to produce butanol in batch culture fermentation. The effects of glucose concentration, butyric acid addition and C/N ratio were studied conventionally (one-factor-at-a-time). Moreover, the interactions between glucose concentration, butyric acid addition and C/N ratio were further investigated to optimize butanol production using response surface methodology (RSM). A central composite design was applied, and a polynomial regression model with a quadratic term was used to analyze the experimental data using analysis of variance (ANOVA). ANOVA revealed that the model was highly significant (p < 0.0001) and the effects of the glucose and butyric acid concentrations on butanol production were significant. The model validation experiment showed 13.82 g/L butanol was produced under optimum conditions. Scale up fermentation in optimized medium resulted in 17 g/L of butanol and 21.71 g/L of ABE. The experimental data of scale up in 5 L bioreactor and flask scale were fitted to kinetic mathematical models published in the literature to estimate the kinetic parameters of the fermentation. The models used gave the best fit for butanol production, biomass and glucose consumption for both flask scale and bioreactor scale up.     

A morphometric study of the protective effect of cryotherapy on oral mucositis in cancer patients treated with 5-fluorouracil

We investigated cytological changes in oral mucosa smears from patients treated with cryotherapy to determine whether cryotherapy prevented mucositis caused by 5-fluorouracil (5-FU) therapy. Patients with gastrointestinal malignancies were divided into four groups; control patients before 5-FU therapy, patients after 5-FU therapy without cryotherapy, patients with cryotherapy before 5-FU therapy and patients with cryotherapy after 5-FU therapy. Oral mucosa samples from all patients were assessed at the beginning and on day 14 of chemotherapy. We used exfoliative cytology to evaluate cellular changes in the oral mucosa that were caused by 5-FU. Smears from each patient were stained using the Papanicolaou method and analyzed using stereology. Smears were taken from each group before and after 5-FU infusion. We found that nuclear volume was decreased significantly in cells of the 5-FU therapy after cryotherapy patients compared to the 5-FU therapy before cryotherapy patients. We also found significantly decreased cytoplasmic volumes in the 5-FU therapy after cryotherapy patients compared to the 5-FU therapy before cryotherapy patients. The results of cytomorphometric estimations revealed that cryotherapy may be used to prevent damage to oral tissue and may decrease the frequency and duration of oral mucositis caused by 5-FU.     

Elevational diversity patterns of small mammals on Mount Kinabalu, Sabah, Malaysia

1 Diversity patterns of small mammals were studied along an elevational transect on Mount Kinabalu, the highest mountain in South‐east Asia, utilizing data from previously existing sources and a new field study. A mark‐and‐release study (conducted during wet and dry seasons between November 1994 and April 1995) resulted in captures of 12 small mammal species, including two species of squirrels, two tree shrews, seven murid rodents and one gymnure. 2 Based on data compiled from this survey, museum specimens, and published and unpublished literature (analysed by locally weighted sums of squares and quadratic polynomial regressions), species richness of small mammals formed a middle elevation bulge, highest at about 1200–1400 m and declining at lower and higher elevations. Trapping during two seasons did not change the assessment of the pattern. 3 A cluster analysis of these data indicated that there are two elevationally associated faunas, one in the highlands and another in the lowlands. The transition between these two assemblages is at 1700–1800 m elevation. The lowland faunal assemblage has the highest number of species, with maximum species richness at about 1300 m for total small mammal species, about 1200 m for arboreal species and about 1400 m for terrestrial species. 4 The areas where much overlapping of species occurs are the elevations where climate and vegetation change rapidly from lowland to montane types. Tree species, gymnosperms, orchids and ferns showed a similar curvilinear pattern along the same elevational gradient, with maximum species richness at about 1400–1500 m. Temperature declined progressively with increasing elevation, but rainfall and humidity reached their highest levels at about 1700 m. 5 Maximum diversity of small mammals thus occurred at the elevation where a highland and a lowland assemblage overlapped, where several types of plants reached their maximum diversity, and where rainfall and humidity reached their maxima. Similar patterns have been documented for small mammals, plants, and climate at sites scattered in Indo‐Australia from Taiwan to New Guinea.     

Lateral wedge with medial only cardiac shielding (LEMONADE) technique in left chest wall adjuvant radiotherapy

BackgroundThis dosimetric study compared lateral wedge with medial only cardiac shielding (LEMONADE) technique, for left chest wall (LCW) irradiation against three other commonly used techniques.Materials and methodsDosimetric parameters of 22 consecutive LBC patients treated using the P1 (LEMONADE technique) were compared with 3 other virtually reconstructed plans : no cardiac shielding with paired wedges; P2 (paired wedges and medial only Y-direction shielding) and P3 (paired wedges and bilateral Y-direction shielding).ResultsP1 showed better target volume (TV) coverage with the mean 90% isodose coverage of 85.59% ± 5.44 compared to 78.90% ± 8.59 and 74.22% ± 9.50 for P2 and P3, respectively. Compared to no cardiac shielding, for a 4.65% drop in TV coverage the V26Gy of heart dropped from 6.68% to a negligible 0.85% for P1. TV receiving < 30Gy is also significantly lesser for P1 compared to P2 and P3 (5.42% vs 10.64% and 15.8%), whilst there is a small difference of 2.75% between no cardiac shielding and P1.ConclusionWith the improvement in BC survival rate, cardiac toxicity associated with adjuvant irradiation for LBC is a major concern. P1 (LEMONADE) technique has a good compromise between cardiac sparing and target coverage and should suffice for most LCW irradiations. Furthermore, the LEMONADE technique is a simple, reproducible and involves fast planning for cardiac sparing, which is ideal for under-resourced departments with heavy workload.     

Antioxidant activities of different parts of Gnetum gnemon L.

Analyses on biological activities of Gnetum gnemon were done to determine the total phenolic and antioxidants of the plant. Four parts of G. gnemon were used in this study, which were leaf, bark, twig, and seeds of the plant. All parts were extracted in methanol, ethanol, hexane, chloroform and hot water using reflux. The total phenolic content of the plant extracts were determined by using Folin-Ciocalteu method. The results demonstrated that the bark from hot water extract showed the highest total phenolic at 10.71?±?0.01 mg GAE/ FDW, while the lowest was chloroform extract of seed at 2.15?±?0.01 mg GAE/ FDW. The antioxidant activity of the plant extracts were determined by using DPPH and FRAP assays, respectively. The DPPH results showed that all plant extracts demonstrated weak free radical scavenging activity tested at the final concentration of 300 μg/ml. In contrast, the methanolic twig extract showed strong reducing power activity (FRAP) at 83.55?±?1.05%, while the hot water seed extract showed the least activity at 41.86?±?4.22% tested at the final concentration of 300 μg/ml. However, there were no correlation between total phenolics and both antioxidant assays tested.     

Distinctive Bacterial Communities in the Rhizoplane of Four Tropical Tree Species

It is known that the microbial community of the rhizosphere is not only influenced by factors such as root exudates, phenology, and nutrient uptake but also by the plant species. However, studies of bacterial communities associated with tropical rainforest tree root surfaces, or rhizoplane, are lacking. Here, we analyzed the bacterial community of root surfaces of four species of native trees, Agathis borneensis, Dipterocarpus kerrii, Dyera costulata, and Gnetum gnemon, and nearby bulk soils, in a rainforest arboretum in Malaysia, using 454 pyrosequencing of the 16S rRNA gene. The rhizoplane bacterial communities for each of the four tree species sampled clustered separately from one another on an ordination, suggesting that these assemblages are linked to chemical and biological characteristics of the host or possibly to the mycorrhizal fungi present. Bacterial communities of the rhizoplane had various similarities to surrounding bulk soils. Acidobacteria, Alphaproteobacteria, and Betaproteobacteria were dominant in rhizoplane communities and in bulk soils from the same depth (0–10?cm). In contrast, the relative abundance of certain bacterial lineages on the rhizoplane was different from that in bulk soils: Bacteroidetes and Betaproteobacteria, which are known as copiotrophs, were much more abundant in the rhizoplane in comparison to bulk soil. At the genus level, Burkholderia, Acidobacterium, Dyella, and Edaphobacter were more abundant in the rhizoplane. Burkholderia, which are known as both pathogens and mutualists of plants, were especially abundant on the rhizoplane of all tree species sampled. The Burkholderia species present included known mutualists of tropical crops and also known N fixers. The host-specific character of tropical tree rhizoplane bacterial communities may have implications for understanding nutrient cycling, recruitment, and structuring of tree species diversity in tropical forests. Such understanding may prove to be useful in both tropical forestry and conservation.     

Sustainable biocatalytic synthesis of L-homophenylalanine as pharmaceutical drug precursor

Over the past decade, L-homophenylalanine is extensively used in the pharmaceutical industry as a precursor for production of angiotensin-converting enzyme (ACE) inhibitor, which possesses significant clinical application in the management of hypertension and congestive heart failure (CHF). A number of chemical methods have been reported thus far for the synthesis of L-homophenylalanine. However, chemical methods generally suffer from process complexity, high cost, and environmental pollution. On the other hand, enantiomerically pure L-homophenylalanine can be obtained elegantly and efficiently by employing biocatalytic methods, where it appears to be the most attractive process in terms of potential industrial applications, green chemistry and sustainability. Herein we review the biocatalytic synthesis of vital L-homophenylalanine as potentially useful intermediate in the production of pharmaceutical drugs in environmentally friendly conditions, using membrane bioreactor for sustainable biotransformation process. One envisages the future prospects of developing an integrated membrane bioreactor system with improved performance for L-homophenylalanine production.     

人HCN4通道的滞后现象:影响窦房结起搏的潜在决定因素(英文)

超极化活化环核苷酸门控(hyperpolarization-activated cyclic-nucleotide-gated,HCN)通道参与调制心脏跳动的节律和速率。与HCN1和HCN2有所不同,慢通道HCN4可能不存在电压依赖的滞后现象。本研究采用单细胞膜片钳方法,在稳定转染hHCN4的HEK293细胞上进行电生理记录,观察hHCN4通道是否存在滞后现象,以及cAMP对其的调制作用;同时采用实时定量RT-PCR方法检测窦房结和心房组织中HCNs的表达。电压钳实验结果显示hHCN4电流(Ih)激活随着保持电位超极化的变化而向去极化方向移动。三角电位变化钳(triangular ramp)和动作电位钳的结果也显示了hHCN4的滞后现象。cAMP增加Ih电流幅度,且使电流激活向去极化方向移动,从而改变内源性hHCN4滞后行为。RT-PCR结果显示,人窦房结组织主要表达HCN4,占75%,HCN1占21%,HCN2占3%,HCN3占0.7%。以上结果提示,人窦房结组织主要表达HCN4亚型,hHCN4的Ih存在电压依赖性的滞后现象,且受cAMP调制。由此推断,hHCN4通道的滞后现象可能在窦房结起搏活动中起到了关键作用。