EPISOME-MEDIATED TRANSFER OF DRUG RESISTANCE IN ENTEROBACTERIACEAE I. : Transfer of Resistance Factors by Conjugation

We have reported in the preceding paper (Watanabe and Fukasawa, 1961) that multiple drug resistance (to streptomycin (Sm), chlor-amphenicol (Cm), tetracycline (Tc), and sul-fonamides (Su)) of Shigellae can be transferred to Escherichia coli, Salmonella typhimurium, and Salmonella enteritidis by conjugation. The respon-sible resistance factors were found to be trans-ferred together and to replicate autonomously in the cytoplasm. Ephrussi, Hottinguer, and Chimenenes (1949) found that cytoplasmic factors of yeast can be eliminated by acriflavine, converting the cells to "petite colonie " mutants. Hirota and lijima (1957) reported that acriflavine converts F+ cells of E. coli strain K-12 to F- by eliminating the F factor. Hirota (1960) further found that the F factor in the integrated state (Hfr) cannot be eliminated by acridines. If our resistance factors are of cytoplasmic nature, it might be possible to eliminate them with acridines and to convert resistant to sensi-tive cells. This possibility was examined in the present paper

Simple simultaneous determination of soluble and insoluble trace metal components in sea salts by a combined coprecipitation/X-ray fluorescence method

An X-ray fluorescence method using the coprecipitation-preconcentration technique has been developed for simple determination of both acid-soluble and insoluble trace metal components, such as manganese, iron, nickel, copper and zinc in sea salts. A salt sample is dissolved in a nitric acid solution, and the residue is filtered off onto a membrane filter. After the pH is adjusted to 7-8, the filtrate is boiled, followed by addition of aluminum carrier, oxine and thionalide solutions. The solution is re-adjusted to pH 9, and kept at 80-85°C for 60 min. The precipitates are filtered off onto another membrane filter. X-Ray fluorescence intensities from two filters loaded with the residue and precipitates are measured and the concentrations of the elements are determined simultaneously using the calibration curves. Detection limits were 0.01 μg g-1 for manganese and copper. 0.04 μg g-1 for nickel and zinc, and 0.05 μg g-1 for iron, regardless of the soluble and the insoluble components. The present method was successfully applied to the analysis of sea salt samples

Effect of interfacial serum proteins on melanoma cell adhesion to biodegradable poly(L-lactic acid) microspheres coated with hydroxyapatite.

We have measured the interaction forces between a murine melanoma cell and a poly(L-lactic acid) (PLLA) microsphere coated with/without hydroxyapatite (HAp) nanoparticles (i.e., an HAp/PLLA or a bare PLLA microsphere) in a serum-free culture medium, using atomic force microscopy (AFM) with colloid probe technique, in order to investigate how the HAp-nanoparticle coating as well as interfacial serum proteins influence the cell-microsphere adhesion. The cell adhesion force of the HAp/PLLA microspheres was 1.4-fold stronger than that of the bare PLLA microspheres. When the microspheres were pretreated with a culture medium supplemented with 10% fetal bovine serum, the cell adhesion force of the HAp/PLLA microspheres was increased by a factor of 2.1; in contrast, no change was observed in the cell adhesion force of the bare PLLA microspheres before/after the pretreatment. Indeed, the cell adhesion force of the HAp/PLLA was 2.8-fold larger than that of the bare PLLA after the pretreatment. Additionally, we have investigated the effect of interfacial serum proteins on the zeta potentials of these microspheres. On the basis of the obtained results, possible mechanism of cell adhesion to the HAp/PLLA and bare PLLA microspheres in the presence/absence of the interfacial serum proteins is discussed

Evaluating staging laparoscopy indications for pancreatic cancer based on resectability classification and treatment strategies for patients with positive peritoneal washing cytology

Abstract Introduction The prognosis of pancreatic ductal adenocarcinoma (PDAC) in patients with positive peritoneal washing cytology (CY1) is poor. We aimed to evaluate the results of staging laparoscopy (SL) and treatment efficacy in CY1 patients based on a resectability classification. Methods We retrospectively reviewed 250 patients with PDAC who underwent SL before the initial treatment between 2017 and 2023 at the University of Toyama. Results The breakdown of cases by resectability classification was resectable (R):borderline resectable (BR):unresectable locally advanced (UR‐LA) = 131:48:71 cases. The frequency of CY1 increased in proportion to the degree of local progression (R:BR:UR‐LA = 20:23:34%), but the frequencies of liver metastasis or peritoneal dissemination were comparable (R:BR:UR‐LA = 6.9:6.3:8.5%). Most CY1 patients received gemcitabine along with nab‐paclitaxel therapy. The CY‐negative conversion rates (R:BR:UR‐LA = 70:64:52%) and conversion surgery rates (R:BR:UR‐LA = 40:27:9%) were inversely proportional to the degree of local progression. Comparing H0P0CY1 factors for each classification, patients with H0P0CY1 had significantly more pancreatic body or tail carcinoma and tumor size ≥32 mm in R patients, whereas in BR patients, duke pancreatic monoclonal antigen type 2 (DUPAN‐2) ≥ 230 U/mL was a significant factor. In contrast, no significant factors were observed in UR‐LA patients. Conclusion The CY1 rates, CY‐negative conversion rates, and conversion surgery rates varied according to local progression. In the case of R and BR, SL could be considered in patients with pancreatic body or tail carcinoma, large tumor size, or high DUPAN‐2 level. In UR‐LA, SL might be considered for all patients

Data from: Mixed mating system are regulated by fecundity in Shorea curtisii (Dipterocarpaceae) as revealed by comparison under different pollen limited conditions

The maintenance of mixed mating was studied in Shorea curtisii, a dominant and widely distributed dipterocarp species in Southeast Asia. Paternity and hierarchical Bayesian analyses were used to estimate the parameters of pollen dispersal kernel, male fecundity and self-pollen affinity. We hypothesized that partial self incompatibility and/or inbreeding depression reduce the number of selfed seeds if the mother trees receive sufficient pollen, whereas reproductive assurance increases the numbers of selfed seeds under low amounts of pollen. Comparison of estimated parameters of self-pollen affinity between high density undisturbed and low density selectively logged forests indicated that self-pollen was selectively excluded from mating in the former, probably due to partial self incompatibility or inbreeding depression until seed maturation. By estimating the self-pollen affinity of each mother tree in both forests, mother trees with higher amount of self-pollen indicated significance of self-pollen affinity with negative estimated value. The exclusion of self-fertilization and/or inbreeding depression during seed maturation occurred in the mother trees with large female fecundity, whereas reproductive assurance increased self-fertilization in the mother trees with lower female fecundity