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Context: Pancreatic neuroendocrine tumors (PNETs) exhibit a wide range of behavior from localized disease to aggressive metastasis. A comprehensive transcriptomic profile capable of differentiating between these phenotypes remains elusive., Objective: Use machine learning to develop predictive models of PNET metastatic potential dependent upon transcriptomic signature., Methods: RNA-sequencing data were analyzed from 95 surgically-resected primary PNETs in an international cohort. Two cohorts were generated with equally balanced metastatic PNET composition. Machine learning was used to create predictive models distinguishing between localized and metastatic tumors. Models were validated on an independent cohort of 29 formalin-fixed, paraffin-embedded samples using NanoString nCounter®, a clinically-available mRNA quantification platform., Results: Gene expression analysis identified concordant differentially expressed genes between the two cohorts. Gene set enrichment analysis identified additional genes that contributed to enriched biologic pathways in metastatic PNETs. Expression values for these genes were combined with an additional 7 genes known to contribute to PNET oncogenesis and prognosis, including ARX and PDX1. Eight specific genes (AURKA, CDCA8, CPB2, MYT1L, NDC80, PAPPA2, SFMBT1, ZPLD1) were identified as sufficient to classify the metastatic status with high sensitivity (87.5% - 93.8%) and specificity (78.1% - 96.9%). These models remained predictive of the metastatic phenotype using NanoString nCounter® on the independent validation cohort, achieving a median AUROC of 0.886., Conclusions: We identified and validated an eight-gene panel predictive of the metastatic phenotype in PNETs, which can be detected using the clinically-available NanoString nCounter® system. This panel should be studied prospectively to determine its utility in guiding operative versus non-operative management., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com. See the journal About page for additional terms.)

Nonsteady-state behaviors are not expected in electric circuits that lack significant capacitance, inductivity, and/or active feedback. Here, we report that electrophoresis on paper─used, e.g., to electrophoretically driven lateral-flow immunoassays (LFIA)─can create a nonsteady-state electric circuit. We studied electrophoresis on 50 × 4 mm nitrocellulose membrane strips utilized in LFIA. The voltage was applied to strip termini immersed in reservoirs with a running buffer. If the electric power of this circuit exceeded approximately 0.5 W, neither the electric current nor the temperature map reached their steady states on a multiminute time scale. The current grew slowly to its maximum and then slowly decreased. The temperature map evolved slowly, with one or more hot spots appearing and disappearing gradually in different positions on the strip. The slow evolution of a temperature map led to the occurrence of a terminal hot spot in which the strip burned. No chaotic behavior was observed, i.e., time dependences of both the current and temperature map were reproducible. We analyzed major processes involved in paper-based electrophoresis and explained the nonsteady-state behavior. Unlike ordinary electric circuits with metal conductors, paper-based electrophoresis involves two slow processes: (i) intense buffer evaporation from hot spots and (ii) buffer supply from the reservoirs by an interplay of the capillary penetration and the electroosmotic flow. These processes affect heat generation and/or dissipation on the strip and, accordingly, the resistivity profile. The slow evolution of the resistivity profile is responsible for the nonsteady-state behavior. The results of our computer modeling support this explanation. The hot spots may have a destructive effect on electrophoretically driven LFIA. To avoid denaturation of immunoreagents, experimentalists should empirically confirm that spatiotemporal temperature maps are compatible with the developed assay.

Serological assays detect the presence of specific antibodies in blood. There are urgent and important applications for serological point-of-care (POC) assays. However, available detection methods are either insufficiently sensitive or too complex for POC settings. Here, we demonstrate that lateral flow immunoassay (LFIA), which is arguably the simplest universal molecular detection approach, can serve as a methodological platform for highly sensitive serological POC assays if combined with a simple, fast, and inexpensive electrophoretic step. In this work, we compared such electrophoretically driven LFIA (eLFIA) with conventional LFIA for the detection of immunoglobulins G against hepatitis B and C in serum. The limit of detection of eLFIA was proven to be 1000 times lower than that of conventional LFIA and sufficiently low to support clinical serological tests. eLFIA takes less than 10 min, requires only a minor accessory powered by a small 9 V battery, and can be performed by an untrained person in the POC environment using a 3 μL specimen of finger-prick capillary blood.

Lateral flow immunoassay (LFIA) is a rapid, simple, and inexpensive point-of-need method. A major limitation of LFIA is a high limit of detection (LOD), which impacts its diagnostic sensitivity. To overcome this limitation, we introduce a signal-enhancement procedure that is performed after completing LFIA and involves controllably moving biotin- and streptavidin-functionalized gold nanoparticles by electrophoresis. The nanoparticles link to immunocomplexes forming multilayer aggregates on the test strip, thus, enhancing the signal. Here, we demonstrate lowering the LOD of hepatitis B surface antigen from approximately 8 to 0.12 ng mL -1 , making it clinically acceptable. Testing 118 clinical samples for hepatitis B showed that signal enhancement increased the diagnostic sensitivity of LFIA from 73 % to 98 % while not affecting its 95 % specificity. Electrophoresis-driven enhancement of LFIA is universal (antigen-independent), takes two minutes, and can be performed by an untrained person., (© 2022 Wiley-VCH GmbH.)

Objective: To improve early treatment outcomes in patients with gastrointestinal polyps using a new device designed for prevention of bleeding during endoscopic minimally invasive polypectomy., Material and Methods: A prospective trial included 35 patients with 36 colonic polyps (stalk diameter >5 mm). Polyp ligation procedure was performed using a novel device providing delivery and tightening the knot before polypectomy., Results: All polyps were successfully removed without any technical difficulties and exposed to histological examination. Mean age of patients was 64 years (52-81), mean dimension of polyps - 15.6 mm (10-40), mean thickness of stalk - 8 mm (5-12). There were no intraoperative and early postoperative complications. All patients were discharged after 2 postoperative days., Conclusion: The proposed method for prevention of bleeding during polypectomy is simple, effective and safe for clinical practice.

Objective: To optimize endoscopic prevention of bleeding during resection of mucous membrane neoplasms of hollow organs of gastrointestinal tract and minimize the risk of intra- and postoperative complications., Material and Methods. A S: Ystematic review and meta-analysis were made in accordance with the PRISMA recommendations. Statistical analysis was performed in Cohrane Review Manager ver. 5.4., Results. There Are 3: Methods of endoscopic prevention of bleeding during polypectomy, i.e. 0.01% adrenaline injection, endoscopic clip placement and endoscopic polyp band ligation. Endoscopic polyp band ligation is characterized by minimum complication rate., Conclusion: Endoscopic polyp band ligation is preferable due to minimum complication rate. If ligation is impossible, prophylactic clip placement may be performed. Adrenaline injection is the least effective method and may be used only if two above-mentioned methods are ineffective.

Large molecules can be generically separated from small ones, though partially and temporarily, in a pressure-driven flow inside a capillary. This transient incomplete separation has been only applied to species with diffusion coefficients different by at least an order of magnitude. Here, we demonstrate, for the first time, the analytical utility of transient incomplete separation for species with close diffusion coefficients. First, we prove in silico that even a small difference in diffusivity can lead to detectable transient incomplete separation of species. Second, we use computer simulation to prove that such a separation can be used for the reliable determination of equilibrium dissociation constant ( K d ) of complexes composed of similar-sized molecules. Finally, we demonstrate experimentally the use of this separation for the accurate determination of K d value for a protein-aptamer complex. We conclude that "accurate constant via transient incomplete separation" (ACTIS) can serve as a reference method for affinity characterization of protein-aptamer binding in solution.

Introduction: Sex-based differences in survival have emerged among patients with pancreatic neuroendocrine tumors (PNETs). Mechanisms driving these differences remain poorly understood. We aimed to further characterize sex-based clinicopathologic and survival differences among patients with PNETs and correlate divergent mutational signatures in these patients., Methods: The National Cancer Database (NCDB) was queried for PNET patients diagnosed 2004-2017 who underwent surgery. Clinicopathologic features were analyzed by sex. The overall survival (OS) of men and women by disease stage was compared using the Kaplan-Meier method. Differences in PNET mutational signatures were analyzed by querying the American Association for Cancer Research Genomics Evidence Neoplasia Information (AACR-GENIE) Cohort v11.0-public. Frequencies of mutational signatures were compared by Fischer's exact (FE) test, adjusting for multiple testing via the Benjamini-Hochberg correction., Results: About 15,202 patients met inclusion criteria from the NCDB; 51.9% were men and 48.1% were women. Men more frequently had tumors > 2 cm than women and more commonly had poorly or undifferentiated tumors. Despite this, lymph node positivity and distant metastases were similar. Differences in OS were only seen among those with early stage rather than stage 3 or 4 disease. MEN1 and DAXX mutations were more frequent among men with PNETs, whereas TP53 mutations were more frequent among women when assessed by FE test. However, neither of these mutational differences maintained statistical significance when adjusted for multiple testing., Conclusion: Compared to women, men have larger tumors but similar rates of distant metastases at time of surgery. OS differences appear to be driven by patients with early-stage disease without clearly identifiable differences in mutational signatures between the sexes., (© 2022. The Society for Surgery of the Alimentary Tract.)

Molecular stream separation (MSS) is a promising complement for continuous-flow synthesis. MSS is driven by forces exerted on molecules by a field applied at an angle to the stream-carrying flow. MSS has only been performed with a 90° field-to-flow angle because of a rectangular geometry of canonic MSS; the second-order rotational symmetry of a rectangle prevents any other angle. Here, we propose a noncanonic circular geometry for MSS, which better aligns with the polar nature of MSS and allows changing the field-to-flow. We conducted in silico and experimental studies of circular geometry for continuous-flow electrophoresis (CFE, an MSS method). We proved two advantages of circular CFE over its rectangular counterpart. First, circular CFE can support better flow and electric-field uniformity than rectangular CFE. Second, the nonorthogonal field-to-flow orientation, achievable in circular CFE, can result in a higher stream resolution than the orthogonal one. Considering that circular CFE devices are not more complex in fabrication than rectangular ones, we foresee that circular CFE will serve as a new standard and a testbed for the investigation and creation of new CFE modalities.

Background: Disparities exist in access to high-volume surgeons, who have better outcomes after thyroidectomy. The association of the Affordable Care Act's Medicaid expansion with access to high-volume thyroid cancer surgery centers remains unclear., Methods: The National Cancer Database was queried for all adult thyroid cancer patients diagnosed from 2010 to 2016. Hospital quartiles (Q1-4) defined by operative volume were generated. Clinicodemographics and adjusted odds ratios for treatment per quartile were analyzed by insurance status. An adjusted difference-in-differences analysis examined the association between implementation of the Affordable Care Act and changes in payer mix by hospital quartile., Results: In total, 241,448 patients were included. Medicaid patients were most commonly treated at Q3-Q4 hospitals (Q3 odds ratios 1.05, P = .020, Q4 1.11, P < .001), whereas uninsured patients were most often treated at Q2-Q4 hospitals (Q2 odds ratios 2.82, Q3 2.34, Q4 2.07, P < .001). After expansion, Medicaid patients had lower odds of surgery at Q3-Q4 compared with Q1 hospitals (odds ratios Q3 0.82, P < .001 Q4 0.85, P = .002) in expansion states, but higher odds of treatment at Q3-Q4 hospitals in nonexpansion states (odds ratios Q3 2.23, Q4 1.86, P < .001). Affordable Care Act implementation was associated with increased proportions of Medicaid patients within each quartile in expansion compared with nonexpansion states (Q1 adjusted difference-in-differences 5.36%, Q2 5.29%, Q3 3.68%, Q4 3.26%, P < .001), and a decrease in uninsured patients treated at Q4 hospitals (adjusted difference-in-differences -1.06%, P = .001)., Conclusions: Medicaid expansion was associated with an increased proportion of Medicaid patients undergoing thyroidectomy for thyroid cancer in all quartiles, with increased Medicaid access to high-volume centers in expansion compared with nonexpansion states., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Recently, the capture of carbon dioxide, the primary greenhouse gas, has attracted particular interest from researchers worldwide. In the present work, several theoretical methods have been used to study adsorption of CO 2 molecules on Li + -decorated coronene (Li + @coronene). It has been established that Li + can be strongly anchored on coronene, and then a physical adsorption of CO 2 will occur in the vicinity of this cation. Moreover, such a decoration has substantially improved interaction energy (E int ) between CO 2 molecules and the adsorbent. One to twelve CO 2 molecules per one Li + have been considered, and their E int values are in the range from -5.55 to -16.87 kcal/mol. Symmetry-adapted perturbation theory (SAPT0) calculations have shown that, depending on the quantity of adsorbed CO 2 molecules, different energy components act as the main reason for attraction. AIMD simulations allow estimating gravimetric densities (GD, wt.%) at various temperatures, and the maximal GDs have been calculated to be 9.3, 6.0, and 4.9% at T = 77, 300, and 400 K, respectively. Besides this, AIMD calculations validate stability of Li + @coronene complexes during simulation time at the maximum CO 2 loading. Bader's atoms-in-molecules (QTAIM) and independent gradient model (IGM) techniques have been implemented to unveil the features of interactions between CO 2 and Li + @coronene. These methods have proved that there exists a non-covalent bonding between the cation center and CO 2 . We suppose that findings, derived in this theoretical work, may also benefit the design of novel nanosystems for gas storage and delivery.

Accurate Constant via Transient Incomplete Separation (ACTIS) is a new method for finding the equilibrium dissociation constant K d of a protein-small molecule complex based on transient incomplete separation of the complex from the unbound small molecule in a capillary. This separation is caused by differential transverse diffusion of the complex and the small molecule in a pressure-driven flow. The advection-diffusion processes underlying ACTIS can be described by a system of partial differential equations allowing for a virtual ACTIS instrument to be built and ACTIS to be studied in silico. The previous in silico studies show that large variations in the fluidic system geometry do not affect the accuracy of K d determination, thus, proving that ACTIS is conceptually accurate. The conceptual accuracy does not preclude, however, instrumental inaccuracy caused by run-to-run signal drifts. Here we report on assembling a physical ACTIS instrument with a fluidic system that mimics the virtual one and proving the absence of signal drifts. Furthermore, we confirmed method ruggedness by assembling a second ACTIS instrument and comparing the results of experiments performed with both instruments in parallel. Despite some unintentional differences between the instruments (caused by tolerances in sizes, positions, etc.) and noticeable differences in their respective separagrams, we found that the K d values determined for identical samples with these instruments were equal. Conclusively, the fluidic system presented here can serve as a template for reliable ACTIS instrumentation.

In molecular-stream separation (MSS), a stream of a multicomponent mixture is separated into multiple streams of individual components. Quantitative evaluation of MSS data has been a bottleneck in MSS for decades as there was no conventional way to present the data in a reproducible and uniform fashion. The roots of the problem were in the multidimensional nature of MSS data; even in the ideal case of steady-state separation, the data is three-dimensional: intensity and two spatial coordinates. We recently found a way to reduce the dimensionality via presenting the MSS data in a polar coordinate system and convoluting the data via integration of intensity along the radius axis. The result of this convolution is an angulagram, a simple 2D plot presenting integrated intensity vs angle. Not only does an angulagram simplify the visual assessment, but it also allows the determination of three quantitative parameters characterizing the quality of MSS: stream width, stream linearity, and stream deflection. Reliably converting an MSS image into an angulagram and accurately determining the stream parameters requires an advanced and user-friendly software tool. In this technical note, we introduce such a tool: the open-source software Topino available at https://github.com/Schallaven/topino. Topino is a stand-alone program with a modern graphical user interface that allows processing an MSS image in a fast (<2 min) and straightforward way. The robustness and ruggedness of Topino were confirmed by comparing the results obtained by three users. Topino removes the analytical bottleneck in MSS and will be an indispensable tool for MSS users with varying levels of experience.

In less than nine months, the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) killed over a million people, including >25,000 in New York City (NYC) alone. The COVID-19 pandemic caused by SARS-CoV-2 highlights clinical needs to detect infection, track strain evolution, and identify biomarkers of disease course. To address these challenges, we designed a fast (30-minute) colorimetric test (LAMP) for SARS-CoV-2 infection from naso/oropharyngeal swabs and a large-scale shotgun metatranscriptomics platform (total-RNA-seq) for host, viral, and microbial profiling. We applied these methods to clinical specimens gathered from 669 patients in New York City during the first two months of the outbreak, yielding a broad molecular portrait of the emerging COVID-19 disease. We find significant enrichment of a NYC-distinctive clade of the virus (20C), as well as host responses in interferon, ACE, hematological, and olfaction pathways. In addition, we use 50,821 patient records to find that renin-angiotensin-aldosterone system inhibitors have a protective effect for severe COVID-19 outcomes, unlike similar drugs. Finally, spatial transcriptomic data from COVID-19 patient autopsy tissues reveal distinct ACE2 expression loci, with macrophage and neutrophil infiltration in the lungs. These findings can inform public health and may help develop and drive SARS-CoV-2 diagnostic, prevention, and treatment strategies.

Continuous-flow electrophoresis (CFE) separates a stream of a multicomponent mixture into multiple streams of individual components inside a thin rectangular chamber. CFE will be able to benefit flow chemistry when it is both compatible with nonaqueous solvents utilized in organic synthesis and capable of generically detecting streams of small organic molecules. While stable nonaqueous CFE has been demonstrated, generically detecting molecular streams has not been achieved yet. Here we propose a general approach for molecular stream visualization in CFE via analyte-caused obstruction of excitation of a fluorescent layer underneath the separation chamber-fluorescent sublayer-based visualization (FSV). The concept of FSC-based visualization has been adapted from visualization of small organic molecules on fluorescent plates in thin-layer chromatography. We designed and fabricated a CFE device with one side made of quartz and another side made of UV-absorbing visibly fluorescent, chemically inert, machinable plastic. This device was demonstrated to support nonaqueous CFE of small organic molecules and quantitative detection of their streams in real-time with a limit of detection below 100 μM. Thus, CFE may satisfy conditions required for its seamless integration with continuous flow organic synthesis in flow chemistry.

Background: DNA methylation (DNAm) is a critical regulator of both development and cellular identity and shows unique patterns in neurons. To better characterize maturational changes in DNAm patterns in these cells, we profile the DNAm landscape at single-base resolution across the first two decades of human neocortical development in NeuN+ neurons using whole-genome bisulfite sequencing and compare them to non-neurons (primarily glia) and prenatal homogenate cortex., Results: We show that DNAm changes more dramatically during the first 5 years of postnatal life than during the entire remaining period. We further refine global patterns of increasingly divergent neuronal CpG and CpH methylation (mCpG and mCpH) into six developmental trajectories and find that in contrast to genome-wide patterns, neighboring mCpG and mCpH levels within these regions are highly correlated. We integrate paired RNA-seq data and identify putative regulation of hundreds of transcripts and their splicing events exclusively by mCpH levels, independently from mCpG levels, across this period. We finally explore the relationship between DNAm patterns and development of brain-related phenotypes and find enriched heritability for many phenotypes within identified DNAm features., Conclusions: By profiling DNAm changes in NeuN-sorted neurons over the span of human cortical development, we identify novel, dynamic regions of DNAm that would be masked in homogenate DNAm data; expand on the relationship between CpG methylation, CpH methylation, and gene expression; and find enrichment particularly for neuropsychiatric diseases in genomic regions with cell type-specific, developmentally dynamic DNAm patterns.

We introduce non-aqueous continuous-flow electrophoresis (NACFE) in which the electrolyte is a solution of an organic salt in an aprotic organic solvent. NACFE can maintain steady-state separation of multiple hydrophobic organic species into individual molecular streams. It is a potential separation complement for continuous-flow organic synthesis. This proof-of-concept work will serve as a justification for efforts towards making NACFE a practical tool in flow chemistry.

Over the past two decades, robotic and minimally invasive cardiac surgery has been continuously refined and is currently an alternative to traditional open-heart surgery for some patients. The parallel evolution of imaging modalities has made robotic surgery safer and more efficient. Here, we review the pre- and post-operative use of computed tomography (CT) in minimally invasive and robotic cardiac procedures., Competing Interests: Conflicts of Interest: The authors have no conflicts of interest to declare.

Differentiating pluripotent cells from fibroblast progenitors is a potentially transformative tool in personalized medicine. We previously identified relatively greater success culturing dura-derived fibroblasts than scalp-derived fibroblasts from postmortem tissue. We hypothesized that these differences in culture success were related to epigenetic differences between the cultured fibroblasts by sampling location, and therefore generated genome-wide DNA methylation and transcriptome data on 11 intrinsically matched pairs of dural and scalp fibroblasts from donors across the lifespan (infant to 85 years). While these cultured fibroblasts were several generations removed from the primary tissue and morphologically indistinguishable, we found widespread epigenetic differences by sampling location at the single CpG (N = 101,989), region (N = 697), "block" (N = 243), and global spatial scales suggesting a strong epigenetic memory of original fibroblast location. Furthermore, many of these epigenetic differences manifested in the transcriptome, particularly at the region-level. We further identified 7,265 CpGs and 11 regions showing significant epigenetic memory related to the age of the donor, as well as an overall increased epigenetic variability, preferentially in scalp-derived fibroblasts-83% of loci were more variable in scalp, hypothesized to result from cumulative exposure to environmental stimuli in the primary tissue. By integrating publicly available DNA methylation datasets on individual cell populations in blood and brain, we identified significantly increased inter-individual variability in our scalp- and other skin-derived fibroblasts on a similar scale as epigenetic differences between different lineages of blood cells. Lastly, these epigenetic differences did not appear to be driven by somatic mutation--while we identified 64 probable de-novo variants across the 11 subjects, there was no association between mutation burden and age of the donor (p = 0.71). These results depict a strong component of epigenetic memory in cell culture from primary tissue, even after several generations of daughter cells, related to cell state and donor age.

Laser-induced changes in the intervertebral discs were studied by the method of atomic force microscopy. Alteration of the proximal caudal intervertebral discs was modeled in rats: puncture and exposure to diode laser (2, 3, or 5 W) in constant or pulse regimens or only puncture (control). Nanostructure of disc surface was estimated by surface skewness, root mean square and average roughness, and coefficient of kurtosis. Maximum positive effect and signs of regenerative changes in the surface microstructure of the intervertebral discs were found after exposure to laser (2-3 W) in constant or pulse regimens.

Retrospective analysis of efficacy of complex treatment, including surgical intervention, radioiodine therapy (RITH), suppressive hormonotherapy of differentiated forms of the thyroid gland cancer (DFTHGC) was done in 281 patients with positive effect of postoperative distant radiation therapy (PDRTH) application as a component of the treatment. Positive effect of therapy was estimated basing on the dynamic scintigraphy data with 131I and determination of thyroglobulin level in blood serum. The PDRTH conduction does not improve prognosis of the disease, does not lower the tumor metastasizing frequency to regional lymph nodes and remote organs and does not replace RITH. To achieve positive result in 12.8% of patients with PDRTH more than two courses of RITH were performed, enhancing so the total radiation dosage on the organism. To provide protracted nonrecurrent survival of patients with DFTHGC the radical approach is necessary, envisaging performance of thyroidectomy, the timely conduction of RITH with subsequent suppressive therapy using L-thyroxin.

There were examined 200 patients aged from 19 to 77 years with differentiated cancer of the thyroid gland (TG). The combined treatment, which included performance of operation, radioiodine therapy and hormonotherapy, was conducted to all the patients. Total and maximum subtotal TG resection was performed in 90% patients, nonradical operation--in 10%, 23% patients were reoperated. Postoperative monitoring according to chart was done with application of dynamic scintigraphy and determination of the thyroglobuline level in the blood serum. The TG residual tissue (RT) was revealed in 61% patients and in 39%--the cancer metastases in the lymphatic nodes. RT of TG was eliminated in 86.8% patients after the first radioiodine therapy course conduction in middle remedial activity (2.79 +/- 0.11) GBq, the metastases devitalization--in 67.9% in middle remedial activity (4.07 +/- 0.12) GBq.

Radioimmunoassay was employed to determine basal levels of LH, FSH, prolactin, total testosterone and 17 beta-estradiol in plasma from 52 pre- or postmenopausal women with prosopalgia consequent to cervical osteochondrosis. The measurements were made before and after laser treatment. Different from the control, basal levels of the hormones and the trends in their changes due to laser therapy depended on the patients' age and the disease stage.

The data on antibiotic sensitivity of 38 strains of S. pneumoniae isolated from children and 46 strains isolated from carriers are presented. The isolates from the carriers had significantly higher sensitivity to benzylpenicillin, ampicillin, methicillin, oxacillin, cefazolin, erythromycin, oleandomycin and lincomycin. Resistance to gentamicin was more frequent in the strains isolated from the carriers. Among the strains of S. pneumoniae isolated from the patients and carriers representatives of serovar K19 were more frequent. There were no statistically reliable difference in them by sensitivity to benzylpenicillin, ampicillin, cefazolin, lincomycin and rifampicin. Still, the isolates from the carriers were much more sensitive to methicillin, oxacillin, oleandomycin and erythromycin.

Staphylococcus epidermidis strain No. 17 containing the bacteriocinogenicity plasmid and incapable of the spontaneous loss of this plasmid was studied. When the contact between the dividing cells was broken by shaking, the cells without the plasmid were shown to appear in the population starting from the 30th minute of cultivation. In all cases the loss of the plasmid due to the action of acridine orange at 37 degrees C and 44 degrees C, as well as in cultivation at 44 degrees C, occurred more frequently when the growing population was shaken than in the absence of shaking. This suggests the possibility of transferring the plasmid controlling bacteriocinogenicity in the process of the growth of staphylococcal population.

Genetic nature of the bacteriogenicity factor of the Staphylococcus epidermidis No. 259 strain was studied by acting upon the strain with ultraviolet irradiation, acridine orange at a temperature of 37 and 44 degrees C, and cultivation of the strain at a temperature of 44 degrees C for 24 and 96 hours. The most effective elimination of the bacteriocinogenicity factor was reached with the action of acridine orange at 44 degrees C and the strain passage at 44 degrees C for 96 hours. A study of 212 subcultures which lost the bacteriocinogenicity factor under the effect of various factors demonstrated that they failed to differ by properties from the initial strain and retained the bacteriocin resistance of the initial strain. A conclusion was drawn that the bacteriocinogenicity factor was an extrachomosomic agent, and was not associated with any other strain properties.

Staphylococcus aureus No. 580 strain contains simultaneously two plasmids: bacteriocinogenicity plasmid and penicillinase plasmid. Both plasmids are lost spontaneously with a high frequency, and also under the effect of acridine orange at temperatures of 37 degrees C and 44 degrees C, and in cultivation at a temperature of 44 degrees C for 5 days. Loss of one of the plasmids failed to lead to stabilization of another plasmid, and it was eliminated spontaneously with the same frequency as in the population of the initial strain. Plasmid loss did not lead to the changes in biochemical and pathogenic properties and also of the phagovar and bacteriogenovar. At the same time in elimination of one or both plasmids lag-phase diminished from 220 to 120 min.

The authors have examined the regularities of the staphylococcal culture filtration through nuclear membranes with pore diameters of up to 0.6 microns, as well as the possibility of sterilization and multiple use of these filters. S. aureus strain No. S. 593 isolated from pathological material has been used as the test bacterium. Routine milk-yolk salt agar and meat-peptone salt broth with 10% NaCl have been employed for the cultivation of the test strain. The filters could be fairly well sterilized with Nikiforov's mixture; then they were dried under a UV bactericidal lamp. The studies have demonstrated that staphylococci can pass through nuclear membranes with pores 0.6 microns in diameter. For sterilization of biologic media membranes with pore diameters of 0.1-0.3 microns are preferable.

The capacity of the bactericinogenicity plasmid in S. epidermidis strain NI 17 to be transferred to nonbactericinogenic staphylococcal strains in mixed populations was studied. 3 out of 22 studied S. aureus strains and 3 out of 24 studied S. epidermidis strains were found to be capable of receiving the plasmid. No recombinants could be obtained with these recipients, which was seemingly due to the presence of the restriction and modification systems in plasmid DNA. The experiments, where the variants of S. epidermidis strain NI 17, having no plasmid, but resistant to antibiotics as the result of mutation, were used as recipients, revealed that the initial strain contained at least 2 plasmids, one of them controlling resistance to cadmium ions and the other responsible for the synthesis of bactericin.

The studies on the genetic structure of Staphylococcus epidermidis, strain 17 showed that this strain possessed a factor of bactericinogenicity of the one type, which was an extrachromosomal element not bound with penicillinase activity. The loss of the bacteriocinogenicity factor spontaneously or under the effect of acridine orange at a temperature of 37 degrees C was not observed. Passages of the strain at a temperature of 44 degrees C for 5 days and acridine orange proved to be the most effective eliminating factors. The loss of the bacteriocinogenicity plasmid did not result in changing any biochemical properties of the strain but was accompanied by a loss of the immunity to bacteriocin of the initial strain. The study of the growth regularities of the initial strain and its variant deprived of the bacteriocinogenicity plasmid showed that multiplication of the cells in the presence of the plasmid practically started without the latent period.

Crude lysates from staphylococcal strains, containing DNA, were capable of transforming Bacillus subtilis at a rate of 1.68 X 10(-10) - 20.6 X 10(-10) depending on the marker according to which the transformers were selected. In a new host, plasmids showed the same behavior pattern as in the staphylococcus but their spontaneous loss was in all the cases recorded significantly more often.

B. subtilis strain 168 was transformed by means of staphylococcal plasmids responsible for resistance to penicillins and levomycetin, as well as for resistance to cadmium ions and for bacteriocinogenicity linked with resistance to cadmium ions. In the new host these plasmids affected the duration of the lag phase and the time of generation. The production of staphylococcal bacteriocin in B. subtilis was accompanied by the lysis of the cells.