Mitochondrial DNA competition: starving out the mutant genome

High levels of pathogenic mitochondrial DNA (mtDNA) variants lead to severe genetic diseases, and the accumulation of such mutants may also contribute to common disorders. Thus, selecting against these mutants is a major goal in mitochondrial medicine. Although mutant mtDNA can drift randomly, mounting evidence indicates that active forces play a role in the selection for and against mtDNA variants. The underlying mechanisms are beginning to be clarified, and recent studies suggest that metabolic cues, including fuel availability, contribute to shaping mtDNA heteroplasmy. In the context of pathological mtDNAs, remodeling of nutrient metabolism supports mitochondria with deleterious mtDNAs and enables them to outcompete functional variants owing to a replicative advantage. The elevated nutrient requirement represents a mutant Achilles' heel because small molecules that restrict nutrient consumption or interfere with nutrient sensing can purge cells of deleterious mtDNAs and restore mitochondrial respiration. These advances herald the dawn of a new era of small-molecule therapies to counteract pathological mtDNAs.

Two mitochondrial DNA polymorphisms modulate cardiolipin binding and lead to synthetic lethality

Genetic screens have been used extensively to probe interactions between nuclear genes and their impact on phenotypes. Probing interactions between mitochondrial genes and their phenotypic outcome, however, has not been possible due to a lack of tools to map the responsible polymorphisms. Here, using a toolkit we previously established in Drosophila, we isolate over 300 recombinant mitochondrial genomes and map a naturally occurring polymorphism at the cytochrome c oxidase III residue 109 (CoIII109) that fully rescues the lethality and other defects associated with a point mutation in cytochrome c oxidase I (CoIT300I). Through lipidomics profiling, biochemical assays and phenotypic analyses, we show that the CoIII109 polymorphism modulates cardiolipin binding to prevent complex IV instability caused by the CoIT300I mutation. This study demonstrates the feasibility of genetic interaction screens in animal mitochondrial DNA. It unwraps the complex intra-genomic interplays underlying disorders linked to mitochondrial DNA and how they influence disease expression.

Strangulation ileus caused by malposition of the ureter

Ileus is one of the most severe diagnoses of the group of acute abdomen events. Some patients with certain forms of bowel obstruction respond well to conservative therapy. However, the diagnosis of strangulation ileus can be delayed in some situations, resulting in high morbidity and mortality in such cases. Our paper presents the case of an 81-year-old female patient who developed an ileus shortly after ureteral stent placement due to obstructive hydroureteronephrosis. The strangulation of the small intestine was caused by an atypical position of the right ureter in the abdominal cavity.

Rapid identification of pathogens in blood serum via Raman tweezers in combination with advanced processing methods

Pathogenic microbes contribute to several major global diseases that kill millions of people every year. Bloodstream infections caused by these microbes are associated with high morbidity and mortality rates, which are among the most common causes of hospitalizations. The search for the "Holy Grail" in clinical diagnostic microbiology, a reliable, accurate, low cost, real-time, and easy-to-use diagnostic method, is one of the essential issues in clinical practice. These very critical conditions can be met by Raman tweezers in combination with advanced analysis methods. Here, we present a proof-of-concept study based on Raman tweezers combined with spectral mixture analysis that allows for the identification of microbial strains directly from human blood serum without user intervention, thus eliminating the influence of a data analyst.

Synchronization of spin-driven limit cycle oscillators optically levitated in vacuum

We explore, experimentally and theoretically, the emergence of coherent coupled oscillations and synchronization between a pair of non-Hermitian, stochastic, opto-mechanical oscillators, levitated in vacuum. Each oscillator consists of a polystyrene microsphere trapped in a circularly polarized, counter-propagating Gaussian laser beam. Non-conservative, azimuthal forces, deriving from inhomogeneous optical spin, push the micro-particles out of thermodynamic equilibrium. For modest optical powers each particle shows a tendency towards orbital circulation. Initially, their stochastic motion is weakly correlated. As the power is increased, the tendency towards orbital circulation strengthens and the motion of the particles becomes highly correlated. Eventually, centripetal forces overcome optical gradient forces and the oscillators undergo a collective Hopf bifurcation. For laser powers exceeding this threshold, a pair of limit cycles appear, which synchronize due to weak optical and hydrodynamic interactions. In principle, arrays of such Non-Hermitian elements can be arranged, paving the way for opto-mechanical topological materials or, possibly, classical time crystals. In addition, the preparation of synchronized states in levitated optomechanics could lead to new and robust sensors or alternative routes to the entanglement of macroscopic objects.

Rapid Identification of Pathogens Causing Bloodstream Infections by Raman Spectroscopy and Raman Tweezers

The search for the "Holy Grail" in clinical diagnostic microbiology-a reliable, accurate, low-cost, real-time, easy-to-use method-has brought up several methods with the potential to meet these criteria. One is Raman spectroscopy, an optical, nondestructive method based on the inelastic scattering of monochromatic light. The current study focuses on the possible use of Raman spectroscopy for identifying microbes causing severe, often life-threatening bloodstream infections. We included 305 microbial strains of 28 species acting as causative agents of bloodstream infections. Raman spectroscopy identified the strains from grown colonies, with 2.8% and 7% incorrectly identified strains using the support vector machine algorithm based on centered and uncentred principal-component analyses, respectively. We combined Raman spectroscopy with optical tweezers to speed up the process and captured and analyzed microbes directly from spiked human serum. The pilot study suggests that it is possible to capture individual microbial cells from human serum and characterize them by Raman spectroscopy with notable differences among different species. IMPORTANCE Bloodstream infections are among the most common causes of hospitalizations and are often life-threatening. To establish an effective therapy for a patient, the timely identification of the causative agent and characterization of its antimicrobial susceptibility and resistance profiles are essential. Therefore, our multidisciplinary team of microbiologists and physicists presents a method that reliably, rapidly, and inexpensively identifies pathogens causing bloodstream infections-Raman spectroscopy. We believe that it might become a valuable diagnostic tool in the future. Combined with optical trapping, it offers a new approach where the microorganisms are individually trapped in a noncontact way by optical tweezers and investigated by Raman spectroscopy directly in a liquid sample. Together with the automatic processing of measured Raman spectra and comparison with a database of microorganisms, it makes the whole identification process almost real time.

SERS-Tags: Selective Immobilization and Detection of Bacteria by Strain-Specific Antibodies and Surface-Enhanced Raman Scattering

Efficient separation and sensitive identification of pathogenic bacterial strains is essential for a prosperous modern society, with direct applications in medical diagnostics, drug discovery, biodefense, and food safety. We developed a fast and reliable method for antibody-based selective immobilization of bacteria from suspension onto a gold-plated glass surface, followed by detection using strain-specific antibodies linked to gold nanoparticles decorated with a reporter molecule. The reporter molecules are subsequently detected by surface-enhanced Raman spectroscopy (SERS). Such a multi-functionalized nanoparticle is called a SERS-tag. The presented procedure uses widely accessible and cheap materials for manufacturing and functionalization of the nanoparticles and the immobilization surfaces. Here, we exemplify the use of the produced SERS-tags for sensitive single-cell detection of opportunistic pathogen Escherichia coli, and we demonstrate the selectivity of our method using two other bacterial strains, Staphylococcus aureus and Serratia marcescens, as negative controls. We believe that the described approach has a potential to inspire the development of novel medical diagnostic tools for rapid identification of bacterial pathogens.

In Vivo Contrast Imaging of Rat Heart with Carbon Dioxide Foam

Widely used classical angiography with the use of iodine contrast agents is highly problematic, particularly in patients with diabetes mellitus, cardiac and pulmonary diseases, or degree III or IV renal insufficiency. Some patients may be susceptible to allergic reaction to the iodine contrast substance. The intravenous injection of a bolus of CO₂ (negative contrast) is an alternative method, which is, however, currently only used for imaging blood vessels of the lower limbs. The aim of our project was to design and test on an animal model a methodology for injecting the CO₂ foam which would minimize the possibility of embolization of the brain tissue and heart infarction, leading to their damage. This is important research for the further promotion of the use of CO₂, which is increasingly important for endovascular diagnosis and treatment, because carbon-dioxide-related complications are extremely rare. CO₂ foam was prepared by the rapid mixing in a 2:1 ratio of CO₂ and fetal bovine serum (FBS)-enriched Dulbecco's Modified Eagle Medium (DMEM). Freshly prepared CO₂ foam was administered into the catheterized rat tail vein or cannulated rat abdominal aorta and inferior vena cava (IVC). CO₂ foam was compared with commercially available microbubbles (lipid shell/gas core). The rat heart in its parasternal long axis was imaged in B-Mode and Non-linear Contrast Mode before/during and after the contrast administration. Samples of the brain, heart and lungs were collected and subjected to histological examination. The non-linear contrast imaging method enables the imaging of micron-sized gas microbubbles inside a rat heart. The significantly shorter lifetime of the prepared CO₂ foam is a benefit for avoiding the local ischemia of tissues.

Raman spectroscopy-a tool for rapid differentiation among microbes causing urinary tract infections

Urinary tract infections belong to the most common infections in the world. Besides community-acquired infections, nosocomial infections pose a high risk especially for patients having indwelling catheters, undergoing urological surgeries or staying at hospital for prolonged time. They can be often complicated by antimicrobial resistance and/or biofilm formation. Therefore, a rapid diagnostic tool enabling timely identification of a causative agent and its susceptibility to antimicrobials is a need. Raman spectroscopy appears to be a suitable method that allows rapid differentiation among microbes and provides a space for further analyses, such as determination of capability of biofilm formation or antimicrobial susceptibility/resistance in tested strains. Our work here presents a possibility to differ among most common microbes causing urinary tract infections (belonging to 20 species). We tested 254 strains directly from colonies grown on Mueller-Hinton agar plates. The results show that it is possible to distinguish among the tested species using Raman spectroscopy, which proves its great potential for future use in clinical diagnostics. Moreover, we present here a pilot study of a real-time analysis and identification (in less than 10 min) of single microbial cells directly in urine employing optical tweezers combined with Raman spectroscopy.

[Risk Factors for the Development of Distal Tibiofibular Synostosis after Unstable Ankle Fractures]

PURPOSE OF THE STUDY The study analyses a cohort of patients with surgically treated ankle fractures who developed complete distal tibiofibular synostoses. It focuses on their occurrence and association with the extent of tibiotalar dislocation of the ankle joint on the trauma X-ray and its relation to the choice of surgery. MATERIAL AND METHODS The cohort of a total of 824 patients with type B and C fractures according to Weber classification was followed up for 9 years. The cohort consisted of 403 (48.9%) men and 421 (51.1%) women. The exclusion criteria included associated talus fractures, calcaneus fractures and fractures of the other bones of the foot. The studied data were obtained retrospectively from medical documentation and by evaluation of trauma X-rays and X-rays obtained during the postoperative checks. The ankle fractures were classified based on the Weber classification and the basic epidemiologic data (age and gender), type of fracture and extent of tibiotalar dislocation of ankle fractures on the trauma X-ray were evaluated. Posttraumatic ankle dislocation was divided into tibiotalar dislocation > 10 mm, tibiotalar dislocation < 10 mm and the group with regular ankle joint. When evaluating the treatment method, the cohort was divided into three groups: Group 1 with one-stage osteosynthesis, Group 2 with temporary K-wire transfixation or external fixation and subsequent secondary conversion to internal osteosynthesis, and Group 3 with definitive transfixation or external fixation of the ankle. The results were statistically evaluated using the Pearson s chi-square test, or the Fisher s exact test for low frequencies. A multivariant logistic regression model was created to identify statistically significant factors contributing to the development of synostosis. The results with the p-value < 0.05 were considered statistically significant. RESULTS In the whole cohort, the synostosis of distal tibiofibular joint was observed in a total of 131 (15.9%) patients. In men it was in 85 (21.1%) cases and in women in 46 (10.9%) cases, which was statistically significant (p < 0.0001). There was a statistically significant difference (p = 0.0020) between the mean age in the group of patients with synostosis (54.4 years) and the mean age in the group of patients without synostosis (49.1 years). Complete distal tibiofibular synostoses were found in 78 (12.7%) fractures classified as type B according to the Weber classification and in 53 (25.5%) type C fractures. When taking into account the gender, synostoses occurred more frequently in men in both types of fractures classified based on the Weber classification, only in type C fractures no statistical significance was established (p = 0.3026). Various size of posttraumatic tibiotalar dislocation was present in both types of fractures. The group with less severe type B ankle fractures showed a statistically significant dominance of synostosis development in cases with large tibiotalar dislocation of more than 10 mm (p<0.0001). In the group with type C fractures different results were obtained. The highest frequency of cases with synostosis was reported in the group with dislocation smaller than 10 mm (p = 0.0698). In the entire cohort, 615 (74.6%) one-stage osteosyntheses were performed and synostoses developed in 77 (12.5%) cases. In 165 (20.0%) patients, transfixation with K-wires or external fixation with subsequent conversion to secondary osteosynthesis were used and synostoses were identified in 50 (30.3%) cases (p < 0.0001). The open fractures showed an insignificantly smaller number of synostoses than the closed fractures (p = 0.5902). DISCUSSION Posttraumatic distal tibiofibular synostoses have varied morphology. A number of studies confirmed that they do not affect much the functional status of the ankle, even despite their extensive finding in the area of syndesmosis is evident on the Xray. Etiologically, a certain role in their development is reported to be played by posttraumatic hematoma in case of damage to deep soft and bony structures of the ankle. CONCLUSIONS A higher occurrence of synostoses was observed in male population, older age patients and also in type C fractures according to the Weber classification. Larger tibiotalar dislocation showed statistical significance in the development of synostoses in type B fractures according to the Weber classification, whereas in type C fractures it was not the main factor contributing to the development of synostosis. In cases where one-staged osteosynthesis was performed, the occurrence of synostoses was statistically significantly lower than in secondary osteosynthesis after temporary stabilisation. Key words: ankle fracture, distal tibiofibular synostosis, ankle joint dislocation, Weber classification, acute surgery, delayed surgery.

[Comparison of Clinical Outcomes of Displaced Diaphyseal Clavicle Fractures]

PURPOSE OF THE STUDY The aim of this retrospective study was to assess the subjective evaluation of treatment by patients with respect to their return to work and recreational sport following the fracture of clavicle diaphysis with posttraumatic shortening of 1.5 cm, or more, treated non-operatively and surgically. MATERIAL AND METHODS Our group of patients consisted of 51 patients (14 females, 37 males) aged between 18 and 89 years (average age 46 years). We concentrated on the parameters of sex, age, side of injury, extent of posttraumatic shortening, method of treatment, return to work or recreational sport, DASH score at one year post non-operative or surgical treatment. Patients who sustained a pathological fracture, fractures of the clavicle combined with an injury of the acromioclavicular joint or simultaneous fracture of the humerus or the ribs were excluded from the study. Patients with open fractures or re-fractures were excluded as well. The indication for treatment selection was based on pre-operative discussion of the doctor with the patient and the Informed Consent was signed. The patient was informed about different treatment options. A shorter period of fixation of the arm and post-operative physiotherapy was mentioned in connection with surgical treatment as well as potential surgical complications. A statistical analysis comparing the data in both groups was conducted using the Fisher exact test. The p-value of 0.05 or less was considered as statistically significant. RESULTS The right side was affected 26 times, the left side 25 times. The shortening ranged from 1.5 to 3.7 cm. 24 patients (8 females, 16 males) aged 21 to 89 years (average 54 years) were treated non-operatively. 27 patients (6 females, 21 males) aged 18 to 74 years (average 38 years) underwent surgery. The difference in sex distribution in both groups was not statistically significant (p = 0.5311). According to the Robinson classification, there were 17 patients with type 2A2 fractures, of whom 8 underwent surgery and 9 were treated non-operatively, 19 patients with type 2B1 fractures, of whom 9 underwent surgery and 10 were treated non-operatively, and 15 patients with type 2B2, of whom 10 underwent surgery and 5 were treated non-operatively. The surgically treated patients prevailed in type 2B2 only, but this difference was not statistically significant (p = 0.2350). In the non-operatively treated group, 23 out of 24 patients returned to pre-injury activities in 3 months on average. Ten patients (48%) reported reaching the same function as on the other side. In the DASH score evaluation, 11 patients reached the value of 0-3.3, five patients 3.4-10, six patients 10.1-30.0 and two reached the score of more than 30. In the evaluation of capacity to work, 15 out of 24 patients were able to work, 11 of them without any restrictions or difficulties. In the evaluation of the sport and playing musical instrument module, 9 out of 24 patients did not engage in sports activities or do not play any musical instruments. In the surgically treated group, 26 out of 27 patients returned to pre-injury activities within 6 weeks. 19 (70%) patients reported reaching the same function as on the other side. In the DASH score evaluation, 19 patients reached the value of 0-3.3, two patients 3.4-10, 5 patients 10.1-30.0 and one patient with nonunion 72.5. Comparison of the average values of the DASH score demonstrated slightly better results achieved by surgical treatment (9.03 vs 6.77). When assessing the work module, 24 out of 27 patients returned to work, 20 of them without any restrictions or difficulties. Out of 27 patients, 4 patients were no longer able to engage in sports activities or to play a musical instrument. Of the 23 remaining patients, 18 did not have any problems, 5 suffered from minimal problems. The group of patients treated non-operatively included one case of non-union and the same applies to the surgically treated group. In 3 patients the removal of hardware was performed, 3 patients underwent revision of the surgical wound because of infection. DISCUSSION The recommendation of the weight-bearing of the upper extremity was similar in both groups, 12 weeks post injury/surgery on average. It is clear that sooner return to work or sports activities in the surgically treated group was preferred by younger patients who expected quicker recovery. Younger patients were less patient and more eager to return to work and sports, while the older patients, on the other hand, were more cautious about possible complications of surgery. CONCLUSIONS The results of our study did not identify any correlation between the clavicle shortening and the indication for surgical treatment. Surgical treatment was preferred by younger patients, more frequently by males. The rationale was supported by the perspective of sooner return to work and favourite sports activities. Their decision was not affected by the known risks of surgical treatment. Evaluation of the DASH score at one year after injury/surgery showed similar results. A higher incidence of complications in the surgically treated group did not lead to negative evaluation of the selected treatment modality by the highly motivated group of patients either. Key words: fractures of the clavicle diaphysis, non-operative treatment, surgical treatment, return to work, return to sports activities, functional results at 1 year.

New and little known species of moth flies (Diptera: Psychodidae: Psychodinae) from Nicaragua

The male of a new species Arisemus venustus sp. n. from Nicaragua, the Cerro Musun Natural Reserve, is described. A. atrasetus (Rapp, 1945) and Platyplastinx tango Quate et Brown, 2004 (Diptera: Psychodidae: Psychodinae) from Nicaragua are redescribed and illustrated on the basis of male morphological characters.

Optically Transportable Optofluidic Microlasers with Liquid Crystal Cavities Tuned by the Electric Field

Liquid crystal microdroplets with readily adjustable optical properties have attracted considerable attention for building reconfigurable optofluidic microsystems for sensing, imaging, and light routing applications. In this quest, development of active optical microcavities serving as versatile integrated sources of coherent light and ultra-sensitive environmental sensors has played a prominent role. Here, we study transportable optofluidic microlasers reversibly tunable by an external electric field, which are based on fluorophore-doped emulsion droplets of radial nematic liquid crystals manipulated by optical tweezers in microfluidic chips with embedded liquid electrodes. Full transparency of the electrodes formed by a concentrated electrolyte solution allows for applying an electric field to the optically trapped droplets without undesired heating caused by light absorption. Taking advantage of independent, precise control over the electric and thermal stimulation of the lasing liquid crystal droplets, we characterize their spectral tuning response at various optical trapping powers and study their relaxation upon a sudden decrease in the trapping power. Finally, we demonstrate that sufficiently strong applied electric fields can induce fully reversible phase transitions in the trapped droplets even below the bulk melting temperature of the used liquid crystal. Our observations indicate viability of creating electrically tunable, optically transported microlasers that can be prepared on-demand and operated within microfluidic chips to implement integrated microphotonic or sensing systems.

Two new Palaearctic species of moth flies (Diptera, Psychodidae, Psychodinae) from the Caucasus Mts

Psychodid specimens were sorted from samples collected during fieldwork in areas in and around the Caucasus Mountains in 2019. Thornburghiella montana sp. nov. (from Georgia) and Pericoma inopinata sp. nov. (from Azerbaijan and Georgia) are described. Differential diagnoses are given and diagnostic characters illustrated.

Psychodidae (Diptera) of Azerbaijan and Georgia - faunistics with biodiversity notes

Records of 46 Psychodidae (Sycoracinae 1, Trichomyiinae 1, Psychodinae 44) species/subspecies are presented in this paper based on specimens collected by sweep-netting in Azerbaijan and Georgia in 2019. Nine species are recorded for the first time since their original description; 12 species are new for Transcaucasia; 22 species are new for Azerbaijan; and 17 species are new for Georgia. Saraiella ressli montana Ježek, 1990 is proposed as a synonym of S. ressli Wagner, 1983, syn. nov. Knowledge of some aspects of the ecology and biogeography of selected (especially rare) species has been expanded and a clear pattern was found in species richness, rare species, and new records in relation to land use, habitat diversity, and preservation of the environment surrounding the sampling site.

Mitochondrial Superoxide Production Decreases on Glucose-Stimulated Insulin Secretion in Pancreatic β Cells Due to Decreasing Mitochondrial Matrix NADH/NAD+ Ratio

Aims: Glucose-stimulated insulin secretion (GSIS) in pancreatic β cells was expected to enhance mitochondrial superoxide formation. Hence, we elucidated relevant redox equilibria. Results: Unexpectedly, INS-1E cells at transitions from 3 (11 mM; pancreatic islets from 5 mM) to 25 mM glucose decreased matrix superoxide release rates (MitoSOX Red monitoring validated by MitoB) and H2O2 (mitoHyPer, subtracting mitoSypHer emission). Novel double-channel fluorescence lifetime imaging, approximating free mitochondrial matrix NADHF, indicated its ∼20% decrease. Matrix NAD+F increased on GSIS, indicated by the FAD-emission lifetime decrease, reflecting higher quenching of FAD by NAD+F. The participation of pyruvate/malate and pyruvate/citrate redox shuttles, elevating cytosolic NADPHF (iNAP1 fluorescence monitoring) at the expense of matrix NADHF, was indicated, using citrate (2-oxoglutarate) carrier inhibitors and cytosolic malic enzyme silencing: All changes vanished on these manipulations. 13C-incorporation from 13C-L-glutamine into 13C-citrate reflected the pyruvate/isocitrate shuttle. Matrix NADPHF (iNAP3 monitored) decreased. With decreasing glucose, the suppressor of Complex III site Q electron leak (S3QEL) suppressor caused a higher Complex I IF site contribution, but a lower superoxide fraction ascribed to the Complex III site IIIQo. Thus, the diminished matrix NADHF/NAD+F decreased Complex I flavin site IF superoxide formation on GSIS. Innovation: Mutually validated methods showed decreasing superoxide release into the mitochondrial matrix in pancreatic β cells on GSIS, due to the decreasing matrix NADHF/NAD+F (NADPHF/NADP+F) at increasing cytosolic NADPHF levels. The developed innovative methods enable real-time NADH/NAD+ and NADPH/NADP+ monitoring in any distinct cell compartment. Conclusion: The export of reducing equivalents from mitochondria adjusts lower mitochondrial superoxide production on GSIS, but it does not prevent oxidative stress in pancreatic β cells.

Multimode fibre probe calibration

Multimode fibres (MMF) used in endoscopy have advantage of small diameter and flexibility, thus causing less damage to living animals. However, the imaging requires wavefront shaping techniques to obtain a sharp image despite the mode dispersion in the waveguide. We suggest version of transmission matrix calibration which uses internal modes of the waveguide and, thus, lessens requirements on the endoscopy apparatus removing the external reference path.

Horse flies (Diptera: Tabanidae) of three West African countries: A faunistic update, barcoding analysis and trypanosome occurrence

Horse flies (Diptera: Tabanidae) are of medical and veterinary importance since they transmit a range of pathogens. The horse fly fauna of tropical Africa is still poorly known, and in some geographical areas has not been studied for decades. This study summarizes the results of tabanid collections performed in three West African countries where only sparse data were previously available, the Central African Republic (CAR), Gabon and Liberia. Of 1093 collected specimens, 28 morphospecies and 26 genospecies belonging to six genera were identified, including the first findings of eleven morphospecies in the countries where horse flies were collected: Philoliche (Subpangonia) gravoti Surcouf, 1908 and Tabanus ianthinus Surcouf, 1907 are new records for Liberia; Ancala fasciata f. mixta (Surcouf, 1914), Tabanus fraternus Macquart, 1846, and T. triquetrornatus Carter, 1915 for CAR; Chrysops longicornis Macquart, 1838, Haematopota albihirta Karsch, 1887, H. bowdeni Oldroyd, 1952, and H. brucei Austen, 1908 for Gabon; and Tabanus secedens f. regnaulti Surcouf, 1912 and T. thoracinus Palisot de Beauvois, 1807 for Gabon and Liberia. Species identification of all 28 morphospecies based on morphological features was further supplemented by barcoding of cytochrome oxidase I (COI). Based on the COI sequences of 115 specimens representing 74 haplotypes, a phylogenetic tree was constructed to illustrate the relationships among the tabanid species found and to demonstrate their intra- and interspecific divergences. Our study enriches the current number of barcoded tabanids with another 22 genospecies. Based on the analysis of molecular data we question the taxonomic relevance of the morphological forms Ancala fasciata f. mixta and Tabanus secedens f. regnaulti. A parasitological survey based on nested PCR of 18S rRNA revealed a high (˜25%) prevalence of Trypanosoma theileri in the studied horse flies, accompanied by two species of monoxenous trypanosomatids, Crithidia mellificae and Blastocrithidia sp.

Beta-hydroxybutyrate in milk as screening test for subclinical ketosis in dairy cows

Ketosis is a very frequent metabolic disease in dairy cows, resulting in lower milk production, impaired fertility and increased frequency of other diseases. The course of the disease is often subclinical, so early detection is very important. The aim of the study was to investigate the relation between the concentration of beta-hydroxybutyrate in blood and milk and to determine the cut-off value in milk for detection of subclinical ketosis. The study included 94 cows, which were in the first third of lactation. Beta-hydroxybutyrate (BHB) concentrations were measured in blood and milk serum using a biochemical analyser. The average concentration of BHB in the blood serum samples was 1.14 mmol/L while in the milk it was about ten times lower at 0.117 mmol/L. A statistically significant positive correlation between the concentration of BHB in blood and milk (r=0.705, p<0.001) was found. In cows with BHB in blood below 2.0 mmol/L a stronger correlation between blood and milk BHB was established (r=0.658, p<0.001) than in cows with blood BHB above 2.0 mmol/L (r=-0.292, p=0.206). Therefore, BHB in milk is a very suitable indicator in the diagnosis of subclinical ketosis as there is a good correlation between BHB in the blood and milk of cows with subclinical ketosis. The cut-off concentration of BHB in milk set at ≥0.080 mmol/L (AUC=0.91±0.03; p<0.001) is a significant indicator for subclinical ketosis in dairy cows. The sensitivity of the test was 94% and specificity 74%. Beta-hydroxybutyrate in milk is a good indicator of subclinical ketosis in dairy cows and can be measured accurately with a biochemical analyser.

Identification of ability to form biofilm in Candida parapsilosis and Staphylococcus epidermidis by Raman spectroscopy

Aim: Finding rapid, reliable diagnostic methods is a big challenge in clinical microbiology. Raman spectroscopy is an optical method used for multiple applications in scientific fields including microbiology. This work reports its potential in identifying biofilm positive strains of Candida parapsilosis and Staphylococcus epidermidis. Materials & methods: We tested 54 S. epidermidis strains (23 biofilm positive, 31 negative) and 51 C. parapsilosis strains (27 biofilm positive, 24 negative) from colonies on Mueller-Hinton agar plates, using Raman spectroscopy. Results: The accuracy was 98.9% for C. parapsilosis and 96.1% for S. epidermidis. Conclusion: The method showed great potential for identifying biofilm positive bacterial and yeast strains. We suggest that Raman spectroscopy might become a useful aid in clinical diagnostics.

Cyclin C: The Story of a Non-Cycling Cyclin

The class I cyclin family is a well-studied group of structurally conserved proteins that interact with their associated cyclin-dependent kinases (Cdks) to regulate different stages of cell cycle progression depending on their oscillating expression levels. However, the role of class II cyclins, which primarily act as transcription factors and whose expression remains constant throughout the cell cycle, is less well understood. As a classic example of a transcriptional cyclin, cyclin C forms a regulatory sub-complex with its partner kinase Cdk8 and two accessory subunits Med12 and Med13 called the Cdk8-dependent kinase module (CKM). The CKM reversibly associates with the multi-subunit transcriptional coactivator complex, the Mediator, to modulate RNA polymerase II-dependent transcription. Apart from its transcriptional regulatory function, recent research has revealed a novel signaling role for cyclin C at the mitochondria. Upon oxidative stress, cyclin C leaves the nucleus and directly activates the guanosine 5’-triphosphatase (GTPase) Drp1, or Dnm1 in yeast, to induce mitochondrial fragmentation. Importantly, cyclin C-induced mitochondrial fission was found to increase sensitivity of both mammalian and yeast cells to apoptosis. Here, we review and discuss the biology of cyclin C, focusing mainly on its transcriptional and non-transcriptional roles in tumor promotion or suppression.

[Injury of Medial Structures in Ankle Fractures - Epidemiological Aspects and Outcomes of Treatment]

PURPOSE OF THE STUDY Ankle fractures are characterised by a high variability of damage to bone and ligament structures which leads to diverse clinical conditions. This study aims to analyse a group of patients with surgically treated ankle fractures, with a focus on evaluating the outcomes of treatment of ankle joint medial structure injuries (medial malleolar fracture, ligament lesions). MATERIAL AND METHODS The analysed group included 186 patients (102 men and 84 women), in whom an ankle fracture surgery was performed in 2015 and 2016. The outcomes of the treatment were evaluated in 111 patients with type B and type C fractures, who underwent a follow-up examination at one year after the surgery consisting in subjective and objective assessment of the condition and an ankle radiograph. The obtained outcomes were processed using the techniques of descriptive statistics and subsequently evaluated through the Pearson´s chi-square test at 5% significance level, or the Fisher´s exact test for low frequencies. RESULTS The mean age of patients in the group was 48.6 years, while it was lower in men than in women (42.8 years compared to 53.9 years). According to Weber classification, 1 % of fractures were classified as a type A fracture, 68 % as a type B, 27 % as a type C. The group of isolated medial malleolar fractures represented 4 % of cases. The medial side of the ankle joint more frequently suffered a ligament lesion (56 %) than a medial malleolar fracture (44 %). The mean age of the patients with a medial malleolar fracture was 51.9 years, whereas the mean age of the patients with a ligament lesion on the medial side of the ankle was 44.2 years. When evaluating the outcomes using the OMA score at one year postoperatively, a statistically significant difference was found (p = 0.002) between the patients with a medial malleolar fracture (OMA 79.9) and the patients with a ligament lesion at the medial side of the ankle joint (OMA 91.2). DISCUSSION The aim of the study was to add more information on medial structures of ankle joint that are of major importance for ensuring stability of ankle fractures. In agreement with the literature, when managing the ankle fractures with an injury suffered on the medial side there is obviously a more uniform approach in cases with medial malleolar fractures. The situation is different in case of the deltoid ligament lesion, when historically there is a certain level of non-uniformity in indications for revision surgeries and treatment of the injured ligament structures. In our group, in the case of ligament lesion on the medial side of the ankle joint an emphasis is put on the fluoroscopy control of the symmetry of tibiotalar joint space before the beginning of the surgery and also after the fibular fracture stabilisation. The revision surgery was indicated in cases where asymmetry of ankle fork was found. The patients considered the treatment outcome better in cases with a ligament lesion than in cases with a medial malleolar fracture. CONCLUSIONS Proper treatment of medial structures of the ankle joint is important for ensuring the stability of ankle fractures. The patients with type B fractures reported better results at one year postoperatively compared to the patients with type C fracture according to the Weber classification. A statistically significantly better results after the ankle fracture surgery were achieved in patients with the presence of a medial ligament lesion compared to the patients with a medial malleolar fracture. Key words:ankle fracture, injury of medial structures, epidemiology, outcomes of treatment.

[Outcomes and Complications of Surgical Treatment for LSS at 1-Year Follow-up - Prospective Study]

PURPOSE OF THE STUDY Lumbar spinal stenosis (LSS) is a serious and fairly frequent disorder with prevalence increasing with age which often results in a disability. The surgical procedures are often very risky due to the greater age of patients with severe stenosis and their comorbidities. The study aimed to assess the functional outcomes and complications in patients who underwent surgical treatment for LSS at one year postoperatively and to identify the differences in the functional outcomes, if any, in dependence on the number of operated segments. MATERIAL AND METHODS It was a prospective study which included 33 patients who underwent surgery at the authors department from 1 November 2015 to 1 October 2016 for LSS, the mean age of patients was 69.5 (43-83) years. The surgery was indicated based on the clinical examination, radiography and MR imaging and consisted in posterior decompression with or without stabilisation and fusion. Pre- and post-operatively, a neurological examination and evaluation of patient difficulties were performed by: VAS - particularly for low back pain (VAS-LB) and lower limb pain (VAS-LL), Oswestry Disability Index (ODI) and Swiss Spinal Stenosis Questionnaire (SSSQ). The evaluation was done at a half year and one year after the surgery. The authors made comparisons in dependence on the number of treated segments (1-2, 3-5 and Th-S stabilisation). RESULTS A significant improvement of all the followed-up parameters was reported at one year postoperatively. At one year after the surgery, the VAS-LB score showed a decrease by 2.39 (p = 0.001), the VAS-LL by 3.26 (p < 0.001), while a decrease by 2 or more points is considered clinically significant. When evaluating the SSSQ questionnaire, a decrease in subjective difficulties (SSSQ-S) was by 0.89 (p < 0.001), in physical function (SSSQ-F) by 0.87 (p < 0.001). In this questionnaire, the satisfaction rate with the surgery was 2 - i.e. somewhat satisfied. Altogether 76% of patients were very or somewhat satisfied, no one was very dissatisfied. When evaluating the ODI, an improvement by 20.6% (p < 0.001) was reported. The authors identified neither any significant differences in the outcomes at a one-year follow-up in dependence on the length of stabilisation, nor any significant differences between the six-months and one-year follow-up. Intraoperative complications occurred in 18%, early postoperative complications in 6% of patients. The ASD developed in 9% within one year. DISCUSSION The authors confirmed a significant improvement of the followed-up parameters (VAS-LB, VAS-LL, SSSQ, ODI) which corresponds with recent literature. The decrease in VAS and ODI in the authors study is more marked than the outcomes stated in literature. The authors outcomes clearly show that there is no correlation with the length of stabilisation and the number of decompressed segments. Conversely, the rate of complications was higher in this group than the rates stated in literature, but majority of complications had no consequences for the patients. CONCLUSIONS In the group of patients with a one-year follow-up the authors confirmed that surgical procedures will result in reduced subjective difficulties of patients, reduced pain and improvement of physical function. A significant improvement of all the followed-up parameters was reported. The authors did not confirm the correlation between the postoperative improvement and the number of treated segments. Key words:lumbar spinal stenosis, quality of life, post-operative outcomes, complications.

Checklist of known moth flies and sand flies (Diptera, Psychodidae) from Armenia and Azerbaijan

All credible and available published records for 17 species of moth flies known so far from Armenia (Phlebotominae 11 species, Psychodinae 6 species) and Azerbaijan (Phlebotominae 18 species) are summarized. The first records of 18 species of Psychodinae (tribes Mormiini, Paramormiini, Psychodini, Pericomaini) from Armenia and 6 new faunistic records (tribes Psychodini, Pericomaini) for the fauna of Azerbaijan are listed. The checklist of recent moth flies from Armenia includes now 35 species, and from Azerbaijan, 24 species.

Detection of Chloroalkanes by Surface-Enhanced Raman Spectroscopy in Microfluidic Chips

Optofluidics, a research discipline combining optics with microfluidics, currently aspires to revolutionize the analysis of biological and chemical samples, e.g., for medicine, pharmacology, or molecular biology. In order to detect low concentrations of analytes in water, we have developed an optofluidic device containing a nanostructured substrate for surface enhanced Raman spectroscopy (SERS). The geometry of the gold surface allows localized plasmon oscillations to give rise to the SERS effect, in which the Raman spectral lines are intensified by the interaction of the plasmonic field with the electrons in the molecular bonds. The SERS substrate was enclosed in a microfluidic system, which allowed transport and precise mixing of the analyzed fluids, while preventing contamination or abrasion of the highly sensitive substrate. To illustrate its practical use, we employed the device for quantitative detection of persistent environmental pollutant 1,2,3-trichloropropane in water in submillimolar concentrations. The developed sensor allows fast and simple quantification of halogenated compounds and it will contribute towards the environmental monitoring and enzymology experiments with engineered haloalkane dehalogenase enzymes.

Cytoprotective activity of mitochondrial uncoupling protein-2 in lung and spleen

Mitochondrial uncoupling protein‐2 (UCP2) mediates free fatty acid (FA)‐dependent H⁺ translocation across the inner mitochondrial membrane (IMM), which leads to acceleration of respiration and suppression of mitochondrial superoxide formation. Redox‐activated mitochondrial phospholipase A2 (mt‐iPLA2γ) cleaves FAs from the IMM and has been shown to acts in synergy with UCP2. Here, we tested the mechanism of mt‐iPLA2γ‐dependent UCP2‐mediated antioxidant protection using lipopolysaccharide (LPS)‐induced pro‐inflammatory and pro‐oxidative responses and their acute influence on the overall oxidative stress reflected by protein carbonylation in murine lung and spleen mitochondria and tissue homogenates. We provided challenges either by blocking the mt‐iPLA₂γ function by the selective inhibitor R‐bromoenol lactone (R‐BEL) or by removing UCP2 by genetic ablation. We found that the basal levels of protein carbonyls in lung and spleen tissues and isolated mitochondria were higher in UCP2‐knockout mice relative to the wild‐type (wt) controls. The administration of R‐BEL increased protein carbonyl levels in wt but not in UCP2‐knockout (UCP2‐KO) mice. LPS further increased the protein carbonyl levels in UCP2‐KO mice, which correlated with protein carbonyl levels determined in wt mice treated with R‐BEL. These results are consistent with the UCP2/mt‐iPLA₂γ antioxidant mechanisms in these tissues and support the existence of UCP2‐synergic mt‐iPLA₂γ‐dependent cytoprotective mechanism in vivo.

Reactive Oxygen Species and Mitochondrial Dynamics: The Yin and Yang of Mitochondrial Dysfunction and Cancer Progression

Mitochondria are organelles with a highly dynamic ultrastructure maintained by a delicate equilibrium between its fission and fusion rates. Understanding the factors influencing this balance is important as perturbations to mitochondrial dynamics can result in pathological states. As a terminal site of nutrient oxidation for the cell, mitochondrial powerhouses harness energy in the form of ATP in a process driven by the electron transport chain. Contemporaneously, electrons translocated within the electron transport chain undergo spontaneous side reactions with oxygen, giving rise to superoxide and a variety of other downstream reactive oxygen species (ROS). Mitochondrially-derived ROS can mediate redox signaling or, in excess, cause cell injury and even cell death. Recent evidence suggests that mitochondrial ultrastructure is tightly coupled to ROS generation depending on the physiological status of the cell. Yet, the mechanism by which changes in mitochondrial shape modulate mitochondrial function and redox homeostasis is less clear. Aberrant mitochondrial morphology may lead to enhanced ROS formation, which, in turn, may deteriorate mitochondrial health and further exacerbate oxidative stress in a self-perpetuating vicious cycle. Here, we review the latest findings on the intricate relationship between mitochondrial dynamics and ROS production, focusing mainly on its role in malignant disease.

Enhancement of the 'tractor-beam' pulling force on an optically bound structure

Recently, increasing attention has been devoted to mastering a new technique of optical delivery of micro-objects tractor-beam'1, 2, 3, 4, 5, 6, 7, 8, 9. Such beams have uniform intensity profiles along their propagation direction and can exert a negative force that, in contrast to the familiar pushing force associated with radiation pressure, pulls the scatterer toward the light source. It was experimentally observed that under certain circumstances, the pulling force can be significantly enhanced6 if a non-spherical scatterer, for example, a linear chain of optically bound objects10, 11, 12, is optically transported. Here we demonstrate that motion of two optically bound objects in a tractor beam strongly depends on theirs mutual distance and spatial orientation. Such configuration-dependent optical forces add extra flexibility to our ability to control matter with light. Understanding these interactions opens the door to new applications involving the formation, sorting or delivery of colloidal self-organized structures.

Aglycemic HepG2 Cells Switch From Aminotransferase Glutaminolytic Pathway of Pyruvate Utilization to Complete Krebs Cycle at Hypoxia

Human hepatocellular carcinoma HepG2 cells are forced to oxidative phosphorylation (OXPHOS), when cultured in aglycemic conditions at galactose and glutamine. These Oxphos cells represent a prototype of cancer cell bioenergetics with mixed aerobic glycolysis and OXPHOS. We aimed to determine fractions of (i) glutaminolytic pathway involving aminotransferase reaction supplying 2-oxoglutarate (2OG) to the Krebs cycle vs. (ii) active segment of the Krebs cycle with aconitase and isocitrate dehydrogenase-3 (ACO-IDH3), which is typically inactive in cancer cells due to the citrate export from mitochondria. At normoxia, Oxphos cell respiration was decreased down to ~15 and ~10% by the aminotransferase inhibitor aminooxyacetate (AOA) or with AOA plus the glutamate-dehydrogenase inhibitor bithionol, respectively. Phosphorylating to non-phosphorylating respiration ratios dropped from >6.5 to 1.9 with AOA and to zero with AOA plus bithionol. Thus, normoxic Oxphos HepG2 cells rely predominantly on glutaminolysis. Addition of membrane-permeant dimethyl-2-oxoglutarate (dm2OG) to inhibited cells instantly partially restored respiration, evidencing the lack of 2OG-dehydrogenase substrate upon aminotransferase inhibition. Surprisingly, after 72 hr of 5% O₂ hypoxia, the AOA (bithionol) inhibition ceased and respiration was completely restored. Thus in aglycemic HepG2 cells, the hypoxia-induced factor (HIF) upregulation of glycolytic enzymes enabled acceleration of glycolysis pathway, preceded by galactolysis (Leloir pathway), redirecting pyruvate via still incompletely blocked pyruvate dehydrogenase toward the ACO-IDH3. Glycolytic flux upregulation at hypoxia was evidently matched by a higher activity of the Leloir pathway in Oxphos cells. Hypoxic Oxphos cells increased 2-fold the NADPH oxidase activity, whereas hypoxic glycolytic cells decreased it. Oxphos cells and glycolytic cells at 5 mM glucose decreased their reduced glutathione fraction. In contrast to aglycemic cells, glycolytic HepG2 cells decreased their respiration at hypoxia despite the dm2OG presence, i.e., even at unlimited respiratory substrate availability for 72 hr at 5% O₂, exhibiting the canonical HIF-mediated adaptation. Nevertheless, their ATP content was much higher with dm2OG as compared to its absence during hypoxic adaptation. Thus, the metabolic plasticity of cancer cells is illustrated under conditions frequently established for solid tumors in vivo, such as aglycemia plus hypoxia. Consequently, a wide acceptance of the irreversible and exclusive Warburg phenotype in cancer cells is incorrect.

Effects of Infrared Optical Trapping on Saccharomyces cerevisiae in a Microfluidic System

Baker's yeast (Saccharomyces cerevisiae) represents a very popular single-celled eukaryotic model organism which has been studied extensively by various methods and whose genome has been completely sequenced. It was also among the first living organisms that were manipulated by optical tweezers and it is currently a frequent subject of optical micromanipulation experiments. We built a microfluidic system for optical trapping experiments with individual cells and used it for the assessment of cell tolerance to phototoxic stress. Using optical tweezers with the wavelength of 1064 nm, we trapped individual Saccharomyces cerevisiae cells for 15 min and, subsequently, observed their stress response in specially designed microfluidic chambers over time periods of several hours by time-lapse video-microscopy. We determined the time between successive bud formations after the exposure to the trapping light, took account of damaged cells, and calculated the population doubling period and cell areas for increasing trapping power at a constant trapping time. Our approach represents an attractive, versatile microfluidic platform for quantitative optical trapping experiments with living cells. We demonstrate its application potential by assessing the limits for safe, non-invasive optical trapping of Saccharomyces cerevisiae with infrared laser light.

Faunistic and bibliographical inventory of moth flies from Ukraine (Diptera, Psychodidae)

All important published records for 11 moth fly species known so far from Ukraine are reviewed (Phlebotominae 10 species, Psychodinae 1 species). Occurrences of two problematic taxa, Phlebotomus (Adlerius) brevis Theodor & Mesghali, 1964 and P. (Larroussius) major major Annandale, 1910, and some synonymies are discussed. Threticusnegrobovi Vaillant, 1972 must be deleted for Ukraine (misstatement). First records of 34 species of Psychodinae (tribes Mormiini, Paramormiini, Psychodini, Pericomaini) and one of Sycoracinae from Ukraine are also listed.

Differentiation between Staphylococcus aureus and Staphylococcus epidermidis strains using Raman spectroscopy

AIM

Raman spectroscopy is an analytical method with a broad range of applications across multiple scientific fields. We report on a possibility to differentiate between two important Gram-positive species commonly found in clinical material - Staphylococcus aureus and Staphylococcus epidermidis - using this rapid noninvasive technique.

MATERIALS & METHODS

For this, we tested 87 strains, 41 of S. aureus and 46 of S. epidermidis, directly from colonies grown on a Mueller-Hinton agar plate using Raman spectroscopy.

DISCUSSION & CONCLUSION

The method paves a way for separation of these two species even on high number of samples and therefore, it can be potentially used in clinical diagnostics.

Antioxidant mechanism of mitochondria-targeted plastoquinone SkQ1 is suppressed in aglycemic HepG2 cells dependent on oxidative phosphorylation

Previously suggested antioxidant mechanisms for mitochondria-targeted plastoquinone SkQ1 included: i) ion-pairing of cationic SkQ1⁺ with free fatty acid anions resulting in uncoupling; ii) SkQ1H₂ ability to interact with lipoperoxyl radical; iii) interference with electron flow at the inner ubiquinone (Q) binding site of Complex III (Q_i), involving the reduction of SkQ1 to SkQ1H₂ by ubiquinol. We elucidated SkQ1 antioxidant properties by confocal fluorescence semi-quantification of mitochondrial superoxide (J_m) and cytosolic H₂O₂ (J_c) release rates in HepG2 cells. Only in glycolytic cells, SkQ1 prevented the rotenone-induced enhancement of J_m and J_c but not basal releases without rotenone. The effect ceased in glutaminolytic aglycemic cells, in which the redox parameter NAD(P)H/FAD increased after rotenone in contrast to its decrease in glycolytic cells. Autofluorescence decay indicated decreased NADPH/NADH ratios with rotenone in both metabolic modes. SkQ1 did not increase cell respiration and diminished J_m established high by antimycin or myxothiazol but not by stigmatellin. The revealed SkQ1 antioxidant modes reflect its reduction to SkQ1H₂ at Complex I I_Q or Complex III Q_i site. Both reductions diminish electron diversions to oxygen thus attenuating superoxide formation. Resulting SkQ1H₂ oxidizes back to SkQ1at the second (flavin) Complex I site, previously indicated for MitoQ₁₀. Regeneration proceeds only at lower NAD(P)H/FAD in glycolytic cells. In contrast, cyclic SkQ1 reduction/SkQ1H₂ oxidation does not substantiate antioxidant activity in intact cells in the absence of oxidative stress (neither pro-oxidant activity, representing a great advantage). A targeted delivery to oxidative-stressed tissues is suggested for the effective antioxidant therapy based on SkQ1.

Two new species of <i>Jungiella</i> (Diptera: Psychodidae: Psychodinae) from the Palaearctic Region

Two new species of Jungiella Vaillant, 1972 are described: Jungiella janiki sp. nov. from the Bílé Karpaty PLA (Czech Republic) and J. syriaca sp. nov. from the Province Al Lathiqiyeh (Syria). Differential diagnoses for males are included and morphological characters illustrated. A catalogue of 37 species of Jungiella known so far is presented.

Quantitative Raman Spectroscopy Analysis of Polyhydroxyalkanoates Produced by Cupriavidus necator H16

We report herein on the application of Raman spectroscopy to the rapid quantitative analysis of polyhydroxyalkanoates (PHAs), biodegradable polyesters accumulated by various bacteria. This theme was exemplified for quantitative detection of the most common member of PHAs, poly(3-hydroxybutyrate) (PHB) in Cupriavidus necator H16. We have identified the relevant spectral region (800–1800 cm⁻¹) incorporating the Raman emission lines exploited for the calibration of PHB (PHB line at 1736 cm⁻¹) and for the selection of the two internal standards (DNA at 786 cm⁻¹ and Amide I at 1662 cm⁻¹). In order to obtain quantitative data for calibration of intracellular content of PHB in bacterial cells reference samples containing PHB amounts—determined by gas chromatography—from 12% to 90% (w/w) were used. Consequently, analytical results based on this calibration can be used for fast and reliable determination of intracellular PHB content during biotechnological production of PHB since the whole procedure—from bacteria sampling, centrifugation, and sample preparation to Raman analysis—can take about 12 min. In contrast, gas chromatography analysis takes approximately 8 h.

Direct measurement of the temperature profile close to an optically trapped absorbing particle

The surface temperature of an absorbing particle trapped in optical tweezers (OTs) is measured using a mixture of two fluorescent dyes. We analyze the dependence of temperature on both laser power and the radial distance from its surface, and we verify the 1/r decrease of temperature with increasing distance from the particle surface. We detect the variations of spectral profiles as the medium temperature changes. The temperature dependent signal, i.e., the ratio of summed intensities from two distinct spectral regions, is affected by the convolution of temperature profile with transfer function of the spectroscopic system. We analyze this effect and determine the temperature increase on the surface of a core-shell particle trapped by OTs.

Two new species of Sycorax (Diptera: Psychodidae: Sycoracinae) from the Oriental Region

Two new species of Sycorax Haliday in Curtis, 1839 are described from Ulu Temburong National Park in Brunei Darussalam: Sycorax konopiki sp. nov. and S. tomkineana sp. nov. Both species were found resting on two frog species: Ansonia leptopus (Günther, 1872) and A. longidigita Inger, 1960. Differential diagnoses for males are included and morphological characters illustrated. Possible host associations of the new species are briefly discussed. DNA barcode sequence (COI) for Sycorax konopiki sp. nov. is also provided.

H₂O₂-Activated Mitochondrial Phospholipase iPLA₂γ Prevents Lipotoxic Oxidative Stress in Synergy with UCP2, Amplifies Signaling via G-Protein-Coupled Receptor GPR40, and Regulates Insulin Secretion in Pancreatic β-Cells

AIMS

Pancreatic β-cell chronic lipotoxicity evolves from acute free fatty acid (FA)-mediated oxidative stress, unprotected by antioxidant mechanisms. Since mitochondrial uncoupling protein-2 (UCP2) plays antioxidant and insulin-regulating roles in pancreatic β-cells, we tested our hypothesis, that UCP2-mediated uncoupling attenuating mitochondrial superoxide production is initiated by FA release due to a direct H2O2-induced activation of mitochondrial phospholipase iPLA2γ.

RESULTS

Pro-oxidant tert-butylhydroperoxide increased respiration, decreased membrane potential and mitochondrial matrix superoxide release rates of control but not UCP2- or iPLA2γ-silenced INS-1E cells. iPLA2γ/UCP2-mediated uncoupling was alternatively activated by an H2O2 burst, resulting from palmitic acid (PA) β-oxidation, and it was prevented by antioxidants or catalase overexpression. Exclusively, nascent FAs that cleaved off phospholipids by iPLA2γ were capable of activating UCP2, indicating that the previously reported direct redox UCP2 activation is actually indirect. Glucose-stimulated insulin release was not affected by UCP2 or iPLA2γ silencing, unless pro-oxidant activation had taken place. PA augmented insulin secretion via G-protein-coupled receptor 40 (GPR40), stimulated by iPLA2γ-cleaved FAs (absent after GPR40 silencing).

INNOVATION AND CONCLUSION

The iPLA2γ/UCP2 synergy provides a feedback antioxidant mechanism preventing oxidative stress by physiological FA intake in pancreatic β-cells, regulating glucose-, FA-, and redox-stimulated insulin secretion. iPLA2γ is regulated by exogenous FA via β-oxidation causing H2O2 signaling, while FAs are cleaved off phospholipids, subsequently acting as amplifying messengers for GPR40. Hence, iPLA2γ acts in eminent physiological redox signaling, the impairment of which results in the lack of antilipotoxic defense and contributes to chronic lipotoxicity.

Identification of individual biofilm-forming bacterial cells using Raman tweezers

A method for in vitro identification of individual bacterial cells is presented. The method is based on a combination of optical tweezers for spatial trapping of individual bacterial cells and Raman microspectroscopy for acquisition of spectral “Raman fingerprints” obtained from the trapped cell. Here, Raman spectra were taken from the biofilm-forming cells without the influence of an extracellular matrix and were compared with biofilm-negative cells. Results of principal component analyses of Raman spectra enabled us to distinguish between the two strains of Staphylococcus epidermidis. Thus, we propose that Raman tweezers can become the technique of choice for a clearer understanding of the processes involved in bacterial biofilms which constitute a highly privileged way of life for bacteria, protected from the external environment.

Candida parapsilosis biofilm identification by Raman spectroscopy

Colonies of Candida parapsilosis on culture plates were probed directly in situ using Raman spectroscopy for rapid identification of specific strains separated by a given time intervals (up to months apart). To classify the Raman spectra, data analysis was performed using the approach of principal component analysis (PCA). The analysis of the data sets generated during the scans of individual colonies reveals that despite the inhomogeneity of the biological samples unambiguous associations to individual strains (two biofilm-positive and two biofilm-negative) could be made.

Optical manipulation of aerosol droplets using a holographic dual and single beam trap

We present optical trapping and manipulation of pure water and salt water airborne droplets of various sizes ranging from sub-micrometers up to several tens of micrometers in a holographic dual and single beam trap. In the dual beam trap, successful fusion of droplets as well as precise delivery of many droplets and manipulation of multiple droplets are demonstrated. Furthermore, employing the transfer of the orbital angular momentum of light from Laguerre-Gaussian beams, we show that the water droplets orbit around the beam propagation axis and their tangential speed can be controlled by beam waist magnitude. We also demonstrate that sub-micrometer sized pure water droplets can be trapped and manipulated by a single beam trap with a relatively low numerical aperture. In this case, multiple stable trapping positions were observed, both theoretically and experimentally, which were due to the optical intensity oscillations in the focal region of the laser beam.

Following the mechanisms of bacteriostatic versus bactericidal action using Raman spectroscopy

Antibiotics cure infections by influencing bacterial growth or viability. Antibiotics can be divided to two groups on the basis of their effect on microbial cells through two main mechanisms, which are either bactericidal or bacteriostatic. Bactericidal antibiotics kill the bacteria and bacteriostatic antibiotics suppress the growth of bacteria (keep them in the stationary phase of growth). One of many factors to predict a favorable clinical outcome of the potential action of antimicrobial chemicals may be provided using in vitro bactericidal/bacteriostatic data (e.g., minimum inhibitory concentrations—MICs). Consequently, MICs are used in clinical situations mainly to confirm resistance, and to determine the in vitro activities of new antimicrobials. We report on the combination of data obtained from MICs with information on microorganisms’ “fingerprint” (e.g., DNA/RNA, and proteins) provided by Raman spectroscopy. Thus, we could follow mechanisms of the bacteriostatic versus bactericidal action simply by detecting the Raman bands corresponding to DNA. The Raman spectra of Staphylococcus epidermidis treated with clindamycin (a bacteriostatic agent) indeed show little effect on DNA which is in contrast with the action of ciprofloxacin (a bactericidal agent), where the Raman spectra show a decrease in strength of the signal assigned to DNA, suggesting DNA fragmentation.

Spectral tuning of lasing emission from optofluidic droplet microlasers using optical stretching

We introduce tunable optofluidic microlasers based on active optical resonant cavities formed by optically stretched, dye-doped emulsion droplets confined in a dual-beam optical trap. To achieve tunable dye lasing, optically pumped droplets of oil dispersed in water are stretched by light in the dual-beam trap. Subsequently, resonant path lengths of whispering gallery modes (WGMs) propagating in the droplet are modified, leading to shifts in the microlaser emission wavelengths. Using this technique, we present all-optical, almost reversible spectral tuning of the lasing WGMs and show that the direction of tuning depends on the position of the pump beam focus on the droplet. In addition, we study the effects of temperature changes on the spectral position of lasing WGMs and demonstrate that droplet heating leads to red-tuning of the droplet lasing wavelength.

Optical trapping of microalgae at 735-1064 nm: photodamage assessment

Living microalgal cells differ from other cells that are used as objects for optical micromanipulation, in that they have strong light absorption in the visible range, and by the fact that their reaction centers are susceptible to photodamage. We trapped cells of the microalga Trachydiscus minutus using optical tweezers with laser wavelengths in the range from 735 nm to 1064 nm. The exposure to high photon flux density caused photodamage that was strongly wavelength dependent. The photochemical activity before and after exposure was assessed using a pulse amplitude modulation (PAM) technique. The photochemical activity was significantly and irreversibly suppressed by a 30s exposure to incident radiation at 735, 785, and 835 nm at a power of 25 mW. Irradiance at 885, 935 and 1064 nm had negligible effect at the same power. At a wavelength 1064 nm, a trapping power up to 218 mW caused no observable photodamage.

Antioxidant activity by a synergy of redox-sensitive mitochondrial phospholipase A2 and uncoupling protein-2 in lung and spleen

Mitochondrial uncoupling protein-2 (UCP2) has been suggested to participate in the attenuation of the reactive oxygen species production, but the mechanism of action and the physiological significance of UCP2 activity remain controversial. Here we tested the hypothesis that UCP2 provides feedback downregulation of oxidative stress in vivo via synergy with an H2O2-activated mitochondrial calcium-independent phospholipase A2 (mt-iPLA2). Tert-butylhydroperoxide or H2O2 induced free fatty acid release from mitochondrial membranes as detected by gas chromatography/mass spectrometry, which was inhibited by r-bromoenol lactone (r-BEL) but not by its stereoisomer s-BEL, suggesting participation of mt-iPLA2γ isoform. Tert-butylhydroperoxide or H2O2 also induced increase in respiration and decrease in mitochondrial membrane potential in lung and spleen mitochondria from control but not UCP2-knockout mice. These data suggest that mt-iPLA2γ-dependent release of free fatty acids promotes UCP2-dependent uncoupling. Upon such uncoupling, mitochondrial superoxide formation decreased instantly also in the s-BEL presence, but not when mt-iPLA2 was blocked by R-BEL and not in mitochondria from UCP2-knockout mice. Mt-iPLA2γ was alternatively activated by H2O2 produced probably in conjunction with the electron-transferring flavoprotein:ubiquinone oxidoreductase (ETFQOR), acting in fatty acid β-oxidation. Palmitoyl-d,l-carnitine addition to mouse lung mitochondria, respiring with succinate plus rotenone, caused a respiration increase that was sensitive to r-BEL and insensitive to s-BEL. We thus demonstrate for the first time that UCP2, functional due to fatty acids released by redox-activated mt-iPLA2γ, suppresses mitochondrial superoxide production by its uncoupling action. In conclusion, H2O2-activated mt-iPLA2γ and UCP2 act in concert to protect against oxidative stress.