Growth rate regulation of lac operon expression in Escherichia coli is cyclic AMP dependent

AbstractIn contrast to the ribosomal RNA gene expression increasing with growth rate, transcription of the lac operon is downregulated by cell growth rate. In continuous culture, growth rate regulation of lac promoter was independent of carbon substrate used and its location on the chromosome. Since the lac operon is activated by cyclic adenosine monophosphate (cAMP), which decreases with increasing cell growth rate, expression of plac-lacZ reporter fusion was analyzed in cya mutant under various growth conditions. The results demonstrated that expression of plac-lacZ in cya mutant was both lower and growth rate independent. In addition, ppGpp (guanosine tetraphosphate) was not involved in the mechanism of growth rate regulation of the lac promoter. Thus, the results of this study indicate that cAMP mediates the growth rate-dependent regulation of lac operon expression in Escherichia coli

Rheology, force transmission, and shear instabilities in frictional granular media from biaxial numerical tests using the contact dynamics method

International audienceBy means of the contact dynamics discrete element method, we investigate the quasi-static behavior of granular media composed of rigid frictional particles. Eluding specific modeling of the contact rheology, this method is suitable for numerical simulation of the plastic deformations of granular materials. We studied the macroscopic stress-strain and volume-change behavior, as well as force transmission and shear instabilities, in a two-dimensional biaxial geometry for dense samples composed of 5000 rigid disks. The peak and residual strengths and shear bands were analyzed by varying the confining pressure and the coefficient of friction between particles. The results are consistent with well-known features of the plasticity of noncohesive granular media. The mechanical behavior is rigid-plastic governed by a Mohr-Coulomb yield criterion and showing strain hardening and softening. Conjugated shear bands characterize plastic failure. The volumetric strain is globally dilatant with considerable expansion observed along shear bands. The macroscopic coefficient of friction, determined from peak and residual strengths, increases nonlinearly and saturates to a constant value as a function of contact friction. The strong force chains are mostly parallel to the major principal stress axis, yet deviations are observed near the shear bands. These chains are often composed of particles that are larger than the average. The deviatoric stress shows small fluctuations often in the form of rapid falls that are correlated with tiny contractional events. This behavior is interpreted in terms of the propagation of dynamic shear instabilities along the shear bands, in close analogy with stick-slip behavior

Laparoscopic management of a giant adrenal cyst

AbstractAdrenal cysts, a rare entity, are usually nonfunctional and asymptomatic. Here, we report a 32-year-old woman who presented with mild breathlessness and vague abdominal fullness and discomfort that had lasted 6 months. Chest radiography showed elevation of the left side of the diaphragm. Abdominal sonography showed an anechoic lesion of >15cm, without a septum, that was situated over the left abdominal area. Abdominal computed tomography (CT) showed a 20cm suprarenal cyst located between the pancreas, spleen, and left kidney, causing anterior displacement of the pancreas and inferior displacement of the left kidney. Magnetic resonance imaging confirmed the CT and sonographic findings, and revealed that the cystic mass was originating from the left adrenal gland. Fluid analysis of the cystic lesion showed no evidence of infection or malignancy. A laparoscopic adrenalectomy was performed. Histopathologically, the adrenal tissue showed no evidence of adenoma or malignancy, and the cystic component showed a flattened endothelial lining with fibrotic tissue, consistent with an endothelial cyst. The postoperative course was uneventful and the patient had no evidence of recurrence during a 6-year follow-up. We discuss the diagnosis and management of adrenal cysts

Improvement of n-butanol tolerance in Escherichia coli by membrane-targeted tilapia metallothionein

Background: Though n-butanol has been proposed as a potential transportation biofuel, its toxicity oftencauses oxidative stress in the host microorganism and is considered one of the bottlenecks preventing itsefficient mass production.Results: To relieve the oxidative stress in the host cell, metallothioneins (MTs), which are known as scavengersfor reactive oxygen species (ROS), were engineered in E. coli hosts for both cytosolic and outer-membrane-targeted (osmoregulatory membrane protein OmpC fused) expression. Metallothioneins from human (HMT),mouse (MMT), and tilapia fish (TMT) were tested. The host strain expressing membrane-targeted TMT showed thegreatest ability to reduce oxidative stresses induced by n-butanol, ethanol, furfural, hydroxymethylfurfural, andnickel. The same strain also allowed for an increased growth rate of recombinant E. coli under n-butanol stress.Further experiments indicated that the TMT-fused OmpC protein could not only function in ROS scavenging butalso regulate either glycine betaine (GB) or glucose uptake via osmosis, and the dual functional fusion proteincould contribute in an enhancement of the host microorganism’s growth rate.Conclusions: The abilities of scavenging intracellular or extracellular ROS by these engineering E. coli wereexamined, and TMT show the best ability among three MTs. Additionally, the membrane-targeted fusion protein,OmpC-TMT, improved host tolerance up to 1.5% n-butanol above that of TMT which is only 1%. These resultspresented indicate potential novel approaches for engineering stress tolerant microorganism strains

Safety and Efficacy of Tien-Hsien Liquid Practical in Patients with Refractory Metastatic Breast Cancer: A Randomized, Double-Blind, Placebo-Controlled, Parallel-Group, Phase IIa Trial

To evaluate the safety and efficacy of Tien-Hsien Liquid Practical (THL-P), a Chinese herbal mixture, in patients with refractory metastatic breast cancer, we performed a randomized, double-blind, placebo-controlled, parallel-group, phase IIa pilot trial. Patients were randomly assigned to either receive THL-P or matching placebo and followed up every 4 weeks for 24 weeks. The primary endpoint was changes in the global health status/quality of life (GHS/QOL) scale. The secondary endpoints were changes in functional and symptom scales, immunomodulating effects, and adverse events. Sixty-three patients were enrolled between June 2009 and June 2011. The intent-to-treat population included 28 patients in the THL-P group and 11 patients in the placebo group. Compared to the placebo group, the THL-P group had significant improvement from baseline to last visit in GHS/QOL (41.7 versus −33.3; P < 0.05), CD3, CD4/CD8, CD19, CD16+56 positive cells (P < 0.05), and higher levels of physical, role, emotional, and cognitive functioning, as well as decreased fatigue and systemic side effects. Treatment-related adverse events were mild constipation and localized itching, and no serious adverse events were reported. THL-P appears to be a safe alternative adjuvant treatment for patients with refractory metastatic breast cancer, as it effectively improves QOL and palliates cancer-related symptoms

Major Complications and Associated Risk Factors of Transrectal Ultrasound Guided Prostate Needle Biopsy: A Retrospective Study of 1875 Cases in Taiwan

Background/PurposeComplications from transrectal ultrasound (TRUS) guided prostate needle biopsy are occasionally encountered in the daily practice of urologists. We tried to determine the associated risk factors of patients who suffered from major complications that required hospitalization after TRUS guided prostate needle biopsies.MethodsWe did a retrospective review of 1875 TRUS guided prostate biopsies performed between January 2002 and December 2005. We defined major complications as patients with complications that needed hospitalization. We analyzed the association between biopsy complications and suspected factors, including age, prostate volume, patient's underlying disease, selection of prophylactic antibiotics, biopsy core numbers (6, 12, and 15 cores), and antiplatelet/anticoagulant usage.ResultsThere were 124 patients (6.6%) with major complication. These major complications were categorized as acute prostatitis (3.8%), acute urinary retention (2.1%), hematuria (1.9%), rectal bleeding (0.2%), epididymitis (0.2%), sepsis (0.05%), and vasovagal syncope (0.05%). Patients with larger prostate size were noted to have higher risk of developing transient acute prostatitis and acute urinary retention after prostate biopsy. In contrast, age, prophylactic antibiotics (levofloxacin and pipemidic acid), underlying diseases (diabetic mellitus, hypertension, hyperlipidemia, cerebrovascular accident, coronary artery disease), increased biopsy core numbers, and antiplatelet/anticoagulant usage were not associated with major complications after prostate biopsy.ConclusionTRUS guided prostate needle biopsy is a safe diagnostic tool in most elderly males with or without systemic underlying disease

Effect of bis(hydroxymethyl) alkanoate curcuminoid derivative MTH-3 on cell cycle arrest, apoptotic and autophagic pathway in triple-negative breast adenocarcinoma MDA-MB-231 cells: An in vitro study

Curcumin has been shown to exert potential antitumor activity in vitro and in vivo involved in multiple signaling pathways. However, the application of curcumin is still limited because of its poor hydrophilicity and low bio-availability. In the present study, we investigated the therapeutic effects of a novel and water soluble bis(hydroxymethyl) alkanoate curcuminoid derivative, MTH-3, on human breast adenocarcinoma MDA-MB-231 cells. This study investigated the effect of MTH-3 on cell viability, cell cycle and induction of autophagy and apoptosis in MDA-MB-231 cells. After 24-h treatment with MTH-3, a concentration-dependent decrease in MDA-MB-231 cell viability was observed, and the IC50 value was 5.37±1.22 μM. MTH-3 significantly triggered G2/M phase arrest and apoptosis in MDA-MB-231 cells. Within a 24-h treatment, MTH-3 decreased the CDK1 activity by decreasing CDK1 and cyclin B1 protein levels. MTH-3-induced apoptosis was further confirmed by morphological assessment and Annexin V/PI staining assay. Induction of apoptosis caused by MTH-3 was accompanied by an apparent increase of DR3, DR5 and FADD and, as well as a marked decrease of Bcl-2 and Bcl-xL protein expression. MTH-3 also decreased the protein levels of Ero1, PDI, PERK and calnexin, as well as increased the expression of IRE1α, CHOP and Bip that consequently led to ER stress and MDA-MB-231 cell apoptosis. In addition, MTH-3-treated cells were involved in the autophagic process and cleavage of LC3B was observed. MTH-3 enhanced the protein levels of LC3B, Atg5, Atg7, Atg12, p62 and Beclin-1 in MDA-MB-231 cells. Finally, DNA microarray was carried out to investigate the level changes of gene expression modulated by MTH-3 in MDA-MB-231 cells. Taken together, our results suggest that MTH-3 might be a novel therapeutic agent for the treatment of triple-negative breast cancer in the near future

Nitroprusside modulates pulmonary vein arrhythmogenic activity

<p>Abstract</p> <p>Background</p> <p>Pulmonary veins (PVs) are the most important sources of ectopic beats with the initiation of paroxysmal atrial fibrillation, or the foci of ectopic atrial tachycardia and focal atrial fibrillation. Elimination of nitric oxide (NO) enhances cardiac triggered activity, and NO can decrease PV arrhythmogensis through mechano-electrical feedback. However, it is not clear whether NO may have direct electrophysiological effects on PV cardiomyocytes. This study is aimed to study the effects of nitroprusside (NO donor), on the ionic currents and arrhythmogenic activity of single cardiomyocytes from the PVs.</p> <p>Methods</p> <p>Single PV cardiomyocytes were isolated from the canine PVs. The action potential and ionic currents were investigated in isolated single canine PV cardiomyocytes before and after sodium nitroprusside (80 μM,) using the whole-cell patch clamp technique.</p> <p>Results</p> <p>Nitroprusside decreased PV cardiomyocytes spontaneous beating rates from 1.7 ± 0.3 Hz to 0.5 ± 0.4 Hz in 9 cells (P < 0.05); suppressed delayed afterdepolarization in 4 (80%) of 5 PV cardiomyocytes. Nitroprusside inhibited L-type calcium currents, transient outward currents and transient inward current, but increased delayed rectified potassium currents.</p> <p>Conclusion</p> <p>Nitroprusside regulates the electrical activity of PV cardiomyocytes, which suggests that NO may play a role in PV arrhythmogenesis.</p

Design of Dual-Band Microstrip Rat Race Coupler with Circuit Miniaturization

Abstract- Rat race ring coupler with stepped-impedance sections is designed to have a dual-band characteristic. This is realized by attaching open stubs to both ends of each stepped-impedance section to create a phase of 900 at two designated frequencies. Transcendental equations are derived for solving impedance ratio R and lengths of the stepped-impedance sections. Circuit with miniaturized area can be obtained ifR&gt; 1 is chosen. Such microstrip ring hybrids operating at 2.45/5.2 GHz with R = 1 and R = 4 are designed and fabricated. Experiments are performed to confirm the theory