Mycolytic effect of extracellular enzymes of antagonistic microbes to Colletotrichum falcatum,red rot pathogen of sugarcane

Strains of selected bacteria and Trichoderma harzianum isolated from sugarcane rhizosphere and endosphere regions were tested for the production of chitinolytic enzymes and their involvement in the suppression of Colletotrichum falcatum, red rot pathogen of sugarcane. Among several strains tested for chitinolytic activity, 12 strains showed a clearing zone on chitin-amended agar medium. Among these, bacterial strains AFG2, AFG 4, AFG 10, FP7 and VPT4 and all the tested T. harzianum strains produced clearing zones of a size larger than 10 mm. The antifungal activity of these strains increased when chitin was incorporated into the medium. Trichoderma harzianum strain T5 showed increased levels of activity of N-acetylglucosaminidase and -1,3-glucanase when grown on minimal medium containing chitin or cell wall of the pathogen. Lytic enzymes of bacterial strains AFG2, AFG4, VPT4 and FP7 and T. harzianum T5 inhibited conidial germination and mycelial growth of the pathogen. Enzymes from T. harzianum T5 were found to be the most effective in inhibiting the fungus. When mycelial discs of the pathogen were treated with the enzymes, electrolytes were released from fungal mycelia. The results indicated that antagonistic T. harzianum T5 caused a higher level of lysis of the pathogen mycelium, and the inhibitory effect was more pronounced when the lytic enzymes were produced using chitin or cell wall of the pathogen as carbon source.     

Decomposition patterns of unprocessed and processed lignocellulosics in a freshwater fish pond

In an attempt to recycle the lignocellulosic wastes like Eichhornia crassipes, Salvinia cucullata and rice (Oryza sativa) straw as manurial inputs in freshwater fish pond ecosystem, a decomposition experiment was carried out in litter bags in an oligotrophic freshwater fish pond environment, with the above mentioned three substrates in unprocessed and microbially processed forms. The loss rates, associated microbial groups, oxygen consumption patterns and other related parameters like carbon, nitrogen, phosphorus, cellulose, hemicellulose and lignin were analysed. The mean daily dry matter loss rates (unprocessed: 10.44>6.97>1.97 and processed: 11.03>8.21>3.67) and oxygen uptake rate (unprocessed: 0.675>0.571>0.568 mg O₂ g^–1 h^–1 and processed: 0.592>0.424>0.407 mg O₂ g^–1 h^–1) in raw and processed substrates were in the sequence Eichhornia > rice straw > Salvinia. The oxygen consumption pattern almost covariated with variations in temperature of pond water, daily dry matter loss rates and fungal counts on substrates. During the decay, the percentage of N and P increased whereas that of C decreased, resulting in lowering of C/N and C/P ratios of the substrates. The structural polymeric fractions like cellulose and hemicellulose decreased along with dry matter whereas the lignin content increased after an initial decrease due to loss of other structural carbohydrates resulting in apparent per cent gain of lignin. A higher number of different heterotrophic bacterial groups was observed in the processed substrates as compared to their raw counterparts. However, cellulolytic bacterial numbers were found to fluctuate through the study period. The fungal load was found to be decreasing gradually as the decay progressed. In this study, bacteria were found to be the prominent microbial group responsible for the decay. The nitrogen-fixing, phosphatase-producing and phosphorus-solubilising bacterial groups were observed to play an important role in lowering the C/N and C/P ratios of the decomposing substrates during decay.     

Rest-inserted loading rapidly amplifies the response of bone to small increases in strain and load cycles.

We hypothesized that a 10-s rest interval (at zero load) inserted between each load cycle would increase the osteogenic effects of mechanical loading near previously identified thresholds for strain magnitude and cycle numbers. We tested our hypothesis by subjecting the right tibiae of female C57BL/6J mice (16 wk, n = 70) to exogenous mechanical loading within a peri-threshold physiological range of strain magnitudes and load cycle numbers using a noninvasive murine tibia loading device. Bone responses to mechanical loading were determined via dynamic histomorphometry. More specifically, we contrasted bone formation induced by cyclic vs. rest-inserted loading (10-s rest at zero load inserted between each load cycle) by first varying peak strains (1,000, 1,250, or 1,600 micro epsilon) at fixed cycle numbers (50 cycles/day, 3 days/wk for 3 wk) and then varying cycle numbers (10, 50, or 250 cycles/day) at a fixed strain magnitude (1,250 micro epsilon). Within the range of strain magnitudes tested, the slope of periosteal bone formation rate (p.BFR/BS) with increasing strain magnitudes was significantly increased by rest-inserted compared with cyclical loading. Within the range of load cycles tested, the slope of p.BFR/BS with increasing load cycles of rest-inserted loading was also significantly increased by rest-inserted compared with cyclical loading. In sum, the data of this study indicate that inserting a 10-s rest interval between each load cycle amplifies bone's response to mechanical loading, even within a peri-threshold range of strain magnitudes and cycle numbers.     

Diagnostic Yield of Universal Urine Toxicology Screening in an Unselected Cohort of Stroke Patients

Background

Illicit drug use increases the risk of cerebrovascular events by a variety of mechanisms. A recent report suggested that universal urine toxicology (UTox) screening of patients with stroke may be warranted. We aimed to evaluate the diagnostic yield of urine drug screening among unselected patients admitted with acute stroke or transient ischemic attack (TIA).

Methods

Using a single-center prospective study design, we evaluated consecutive patients with acute ischemic stroke, TIA, intracerebral hemorrhage (ICH), or subarachnoid hemorrhage (SAH) over one year. Urine samples were collected within 48 hours of admission and analyzed for common classes of abused drugs. Prevalence of positive UTox screening was determined. We evaluated whether baseline demographics and clinical factors were associated with UTox results.

Results

Of 483 eligible patients (acute ischemic stroke 66.4%; TIA 18.8%; ICH 7.7%; SAH 7.0%), 414 (85.7%) completed UTox screening. The mean (standard deviation) age was 65.1 (15.6) years, 52.7% were male, and 64.3% were Caucasian. Twenty-two (4.6%) patients had positive screening—cannabinoids were detected in 13 cases (3.1%), cocaine in 5 cases (1.2%), amphetamines in 1 case, and phencyclidine in 1 case. The highest yield (14.1%) was observed in patients < 60 years old with history of tobacco use while it was < 5% in the remaining subgroups (p<0.01).

Conclusions

Consistent with current guidelines, a selective approach to UTox screening should be pursued in acute stroke evaluation. The highest diagnostic yield is likely to be for cannabinoids and cocaine testing in younger patients with a history of concurrent tobacco use.     

Atomic force microscopy (AFM) imaging suggests that stromal interaction molecule 1 (STIM1) binds to Orai1 with sixfold symmetry

Depletion of Ca²⁺ from the endoplasmic reticulum (ER) lumen triggers the opening of Ca²⁺ release-activated Ca²⁺ (CRAC) channels at the plasma membrane. CRAC channels are activated by stromal interaction molecule 1 (STIM1), an ER resident protein that senses Ca²⁺ store depletion and interacts with Orai1, the pore-forming subunit of the channel. The subunit stoichiometry of the CRAC channel is controversial. Here we provide evidence, using atomic force microscopy (AFM) imaging, that Orai1 assembles as a hexamer, and that STIM1 binds to Orai1 with sixfold symmetry. STIM1 associates with Orai1 in the form of monomers, dimers, and multimeric string-like structures that form links between the Orai1 hexamers. Our results provide new insights into the nature of the interactions between STIM1 and Orai1.     

Structure of Smad1 MH1/DNA complex reveals distinctive rearrangements of BMP and TGF-β effectors

Smad1 is a downstream effector of the BMP signaling pathway that binds regulatory DNA to execute gene expression programs leading to, for example, the maintenance of pluripotency in mice. On the contrary, the TGF-β-activated Smad3 triggers strikingly different programs such as mesodermal differentiation in early development. Because Smad1 and Smad3 contain identical amino acids at the DNA contact interface it is unclear how they elicit distinctive bioactivities. Here, we report the crystal structure of the MH1 domain of Smad1 bound to a palindromic Smad binding element. Surprisingly, the DNA contact interface of Smad1 is drastically rearranged when compared to Smad3. The N-terminal helix 1 of Smad1 is dislodged from its intramolecular binding site and adopts a domain swapped arrangement with a symmetry-related molecule. As a consequence, helix 2 kinks away from the double helix disabling several key phosphate backbone interactions. Thermal melting analysis corroborates a decompacted conformation of Smad1 and DNA binding assays indicate a lower overall affinity of Smad1 to DNA but increased cooperativity when binding to palindromic DNA motifs. These findings suggest that Smad1 and Smad3 evolved differential qualities to assemble on composite DNA elements and to engage in co-factor interactions by remodeling their N-termini.     

Surgical removal of duct occluder device under mild hypothermia without cardiopulmonary bypass

Because the use of percutaneous intervention is increasing for the closure of the patent ductus arteriosus, the procedure-related complications are also on rise, with migration of the device being most common. The routine practice is to remove the migrated duct occluder device under cardiopulmonary bypass. Amplatzer duct occluder used in a 4-month-old infant dislodged into the descending thoracic aorta. It was removed by the posterolateral thoracotomy under mild hypothermia through juxtaductal aortotomy between the aortic cross-clamps. The use of cardiopulmonary bypass is thus avoided.     

<Emphasis Type="Italic">Trigonella foenum-graecum</Emphasis> (Fenugreek) Protects Against Selenite-Induced Oxidative Stress in Experimental Cataractogenesis

Cataract is the opacification in eye lens and leads to 50% of blindness worldwide. The present study was undertaken to evaluate the anticataract potential of Trigonella foenum-graecum Linn seeds (fenugreek) in selenite-induced in vitro and in vivo cataract. In vitro enucleated rat lenses were maintained in organ culture containing Dulbecco’s modified Eagles medium (DMEM) alone or in addition with 100 μM selenite and served as the normal and control groups, respectively. For the test group, the medium was supplemented with selenite and T. foenum-graecum aqueous extract. The lenses were incubated for 24 h at 37°C. After incubation, the lenses were processed for the estimation of reduced glutathione (GSH), lipid peroxidation product (malondialdehyde), and the antioxidant enzymes. In vivo selenite cataract was induced in 9-day-old rats by subcutaneous injection of sodium selenite (25 μmol/kg body weight). Animals in the test group were injected with different doses of aqueous extract of T. foenum-graecum 4 h before the selenite challenge. A fall in GSH and a rise in malondialdehyde levels were observed in control as compared to normal lenses. T. foenum-graecum significantly (P < 0.01) restored glutathione and decreased malondialdehyde levels. A significant restoration in the activities of antioxidant enzymes such as superoxide dismutase (P < 0.01), catalase, (P < 0.01), glutathione peroxidase (P < 0.01), and glutathione-S-transferase (P < 0.01) was observed in the T. foenum-graecum supplemented group as compared to control. In vivo, none of the eyes was found with nuclear cataract in treated group as opposed to 72.5% in the control group. T. foenum-graecum protects against experimental cataract by virtue of its antioxidant properties. Further studies are warranted to explore its role in human cataract.