ATP stimulates chemically sensitive and sensitizes mechanically sensitive afferents

We examined whether ATP stimulation of P2X purinoceptors would raise blood pressure in decerebrate cats. Femoral arterial injection of the P2X receptor agonist alpha,beta-methylene ATP into the blood supply of the triceps surae muscle induced a dose-dependent increase in arterial blood pressure. The maximal increase in mean arterial pressure (MAP) evoked by 0.1, 0.2, and 0.5 mM alpha,beta-methylene ATP (0.5 ml/min injection rate) was 6.2 +/- 2.5, 22.5 +/- 4.4, and 35.2 +/- 3.9 mmHg, respectively. The P2X receptor antagonist pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid (2 mM ia) attenuated the increase in MAP elicited by intra-arterial alpha,beta-methylene ATP (0.5 mM), whereas the P2Y receptor antagonist reactive blue 2 (2 mM ia) did not affect the MAP response to alpha,beta-methylene ATP. In a second group of experiments, we tested the hypothesis that ATP acting through P2X receptors would sensitize muscle afferents and, thereby, augment the blood pressure response to muscle stretch. Two kilograms of muscle stretch evoked a 26.5 +/- 4.3 mmHg increase in MAP. This MAP response was enhanced when 2 mM ATP or 0.1 mM alpha,beta-methylene ATP (0.5 ml/min) was arterially infused 10 min before muscle stretch. Furthermore, this effect of ATP on the pressor response to stretch was attenuated by 2 mM pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid (P < 0.05) but not by the P1 purinoceptor antagonist 8-(p-sulfophenyl)-theophylline (2 mM). These data indicate that activation of ATP-sensitive P2X receptors evokes a skeletal muscle afferent-mediated pressor response and that ATP at relatively low doses enhances the muscle pressor response to stretch via engagement of P2X receptors.     

Ultrasound sensitive enzyme-membrane

Summary Glucose oxidase (GOD) was immobilized on an acetylcellulose membrane filter (pore size: 0.45 m) with dipalmitoyl phosphatidyl-choline (DPPC). The activity of the GOD-DPPC membrane appeared during ultrasonic irradiation while the GOD activity disappeared when the irradiation was stopped. The apparent GOD activity (the value of the output current decrease of an oxygen electrode in the reaction mixture) gradually increased with increasing ultrasonic power below 3 W. On the other hand, it decreased with the increase in ultrasonic power over 4 W because dissolved oxygen in the reaction mixture in creased as ultrasonic cavitation was generated. The response of the membrane decreased with increasing ultrasonic frequency and the response of the membrane to ultrasound waves (20 KHz, 3 W) was reproducible. The membrane was stable for at least 2 months at 5°C. We conclude that the GOD-DPPC membrane can be regarded as a ultrasound sensitive membrane.     

Genetic analysis of radiation sensitive and chemical-mutagen sensitive mutants of Pseudomonas aeruginosa.

Thirty-five mutants of Pseudomonas aeruginosa sensitive to methyl methanesulfonate (MMS) have been genetically characterized. They constitute ten separable groups as defined by transduction and conjugation. Three of the groups have been shown to be cotransducible with auxotrophic markers.     

Antimicrobial sensitive of Morganella morganii

The aim of this study was the evaluation of the antimicrobial sensitive of Morganella morganii rods isolated from clinical samples. This study included 50 of M. morganii strains isolated in the Clinical Microbiology Department of dr. A. Jurasz University Hospital in 2008-2009. All of strains were sensitive to carbapenems (imipenem, meropenem, ertapenem, doripenem) and piperacillin/tazobactam and most of them to beta-lactam antibiotics, aminoglycosides and fluorochinolons. Resistance to tetracyclines demonstrated 38,0% strains and to doxycycline - 40,0%. One out of 6 strains isolated from urine samples were sensitive to nitrofurantoin. Extended Spectrum Beta-Lactamases were produced by 5 (10,0%) strains.     

Genetic analysis of an osmotic sensitive

Summary The genetic analysis of VY1160 sorbitol dependent, osmotic sensitive yeast mutant led to the identification of three different nuclear recessive mutations. Two of them, designated sorb^- and ts1 are closely linked to one another. The mutation sorb^- determines the lysis, while the mutation tsl increases the ability for lysis of the sorbitol dependent cells. The third mutation ts2 segregates independently from the other two and confers the sensitivity of VY1160 mutant cells towards rifampicin.     

Phytochrome-mediated germination of very sensitive oospores

The light receptor and its mode of operation were studied in photosensitive oospores of Nitella furcata subsp. megacarpa (Allen emend. Wood). Brief pulses of light activated maximal germination of post-secondary dormant oospores removed from lake sediments. Fluence response data at 12 wavelengths were used to construct an action spectrum for germination. The shape of the action spectrum with its maximum at 669 nm provides evidence for the involvement of phytochrome. Germination was induced with photon fluences that established as little as 0.01% of the phytochrome in the far red-absorbing form, which suggests that phytochrome was operating in the very low-fluence response mode. The functioning of phytochrome in the very low-fluence response mode in Nitella is similar to that in higher plants.     

A sensitive microassay of nucleic acids

A simple procedure is described for fluorometric assay of small quantities of DNA and RNA. It is highly reproducible, and sensitive to less than 10⁻⁸ g of native DNA.     

Temperature sensitive phosphoproteins in rat cells transformed by a temperature sensitive mutant of rous sarcoma virus

The localization of the src-encoded protein kinase was examined by fractionating cellular extracts from rat cells transformed by a wild type and a temperature-sensitive mutant of Rous sarcoma virus (SR-A 3Y1 and ts68 3Y1 cells). It was found to be specifically localized in the post-microsomal supernatant (PMS) fraction. Furthermore, it was noticed that a protein with a molecular weight of 16,000 (16K-protein) in the PMS fraction was phosphorylated in vitro when the PMS fraction from ts68 3Y1 cells was preincubated at 33 degrees C, but not at 42 degrees C. This protein was phosphorylated when the fraction from SR-A 3Y1 cells was preincubated at 33 degrees C and at 42 degrees C. Similar temperature-sensitive phosphorylation of 16K-protein was also observed in the PMS fraction from ts68 3Y1 cells labeled in vivo with [32P]orthophosphate at 33 degrees C. These results suggest that this 16K-protein might be a candidate for the endogenous acceptor for the src-encoded protein kinase.     

Stress sensitive glucose oxidase-nylon membrane

Summary Glucose oxidase (GOD) was immobilized on a nylon membrane. No activity of the GOD-nylon membrane was observed under normal conditions but it appeared when the membrane was mechanically stretched. A linear relationship was observed between the stress strength and the GOD activity of the membrane. The appearance of the GOD activity of the membrane with stress was reproducible and the membrane could be stored for at least 2 months. Therefore, the GOD-nylon membrane can be called a stress sensitive membrane.     

Nitroalkylation--a redox sensitive signaling pathway

Redox-sensitive posttranslational modification emerged as important signaling mechanisms. Besides other posttranslational modifications nitroalkylation by nitrated fatty acids mediate favorable anti-inflammatory effects. This review gives an overview of the generation and the reactivity of nitrated fatty acids. Additionally, it provides insights into the so far described pathways regulated by nitrated fatty acids. This article is part of a Special Issue entitled Regulation of Cellular Processes by S-nitrosylation.