Loading...
(1/6342) Carcinogenicity of triethanolamine in mice and its mutagenicity after reaction with sodium nitrite in bacteria.

Mice fed a diet containing 0.3 or 0.03% triethanolamine developed malignant tumors. Females showed a high incidence of tumors in lymphoid tissues, while this type was absent in males. Tumors in other tissues were produced at a considerable rate in both sexes, but no hepatoma was found. Triethanolamine was not mutagenic to Bacillus subtilis by itself, but it became mutagenic after reacting with sodium nitrite under acidic conditions or when the mixture was heated. Although N-nitrosodiethanolamine, a known carcinogen and mutagen, was detected in the reaction mixture by thin-layer chromatography, it may not be the main mutagenic product, because the product was a stable and direct mutagen and its mutagenic activity was destroyed by liver enzymes, unlike N-nitrosodiethanolamine. The lethal and mutagenic DNA damages produced by this unidentified product were susceptible to some extent to the repair functions of the bacteria.  (+info)

(2/6342) Involvement of tumor necrosis factor alpha and interleukin-1beta in enhancement of pentylenetetrazole-induced seizures caused by Shigella dysenteriae.

Neurologic manifestations, mainly convulsions, are the most frequent extraintestinal complications of shigellosis. We used an animal model to study the roles of tumor necrosis factor alpha (TNF-alpha) and interleukin-1 beta (IL-1beta) in Shigella-related seizures. Administration of Shigella dysenteriae 60R sonicate enhanced the sensitivity of mice to the proconvulsant pentylenetetrazole (PTZ) within 7 h. This was indicated by a significantly higher mean convulsion score and an increased number of mice responding with clonic-tonic seizures in the Shigella-pretreated group. Preinjection of mice with anti-murine TNF-alpha (anti-mTNF-alpha) or anti-murine IL-1beta (anti-mIL-1beta) 30 min prior to administration of Shigella sonicate abolished their enhanced response to PTZ at 7 h. Mean convulsion scores were reduced by anti-mTNF-alpha from 1.2 to 0.8 (P = 0.017) and by anti-mIL-1beta from 1.3 to 0.7 (P = 0.008). Preinjection of anti-mTNF-alpha also reduced the percentage of mice responding with clonic-tonic seizures, from 48 to 29% (P = 0.002), and preinjection of anti-mIL-1beta reduced it from 53 to 21% (P = 0. 012). Neutralization of TNF-alpha or IL-1beta did not protect the mice from death due to S. dysenteriae 60R. These findings indicate that TNF-alpha and IL-1beta play a role in the very early sensitization of the central nervous system to convulsive activity after S. dysenteriae administration. Similar mechanisms may trigger neurologic disturbances in other infectious diseases.  (+info)

(3/6342) A novel trans-complementation assay suggests full mammalian oocyte activation is coordinately initiated by multiple, submembrane sperm components.

To initiate normal embryonic development, an egg must receive a signal to become activated at fertilization. We here report that the ability of demembranated sperm heads to activate is abolished after incubation over the range 20-44 degreesC and is sensitive to reducing agents. On the basis of this observation, we have developed a microinjection-based, trans-complementation assay in order to dissect the heat-inactivated sperm-borne oocyte-activating factor(s) (SOAF). We demonstrate that the failure of heat-inactivated sperm heads to activate an egg is rescued by coinjection with dithiothreitol-solubilized SOAF from demembranated sperm heads. The solubilized SOAF (SOAFs) is trypsin sensitive and is liberated from demembranated heads in a temperature-dependent manner that inversely correlates with the ability of sperm heads to activate. This argues that SOAFs is a proteinaceous molecular species required to initiate activation. Injection of oocytes with mouse or hamster sperm cytosolic factors, but not SOAFs alone, induced resumption of meiosis, further suggesting that these cytosolic factors and SOAF are distinct. Collectively, these data strongly suggest that full mammalian oocyte activation is initiated by the coordinated action of one or more heat-sensitive protein constituents of the perinuclear matrix and at least one heat-stable submembrane component.  (+info)

(4/6342) Obstructive uropathy and hydronephrosis in male KK-Ay mice: a report of cases.

Uropathy associated with hydronephrosis was observed frequently in our male KK-Ay mouse colony during a long-term study of diabetes. The lesion occurred in 24 of the 31 KK-Ay male mice and accounted for the greatest number of spontaneous deaths among them. It was observed after 4 months of age and involved about hard plugs of altered seminal material resembling the seminal vesicle secretion. The plugs became impacted in the urethral bulb and the bladder. The penile anatomy, with its flexure, pressure on the urethra from the bulbocavernosus muscle, and the characteristic ability of the seminal fluid to easily coagulate to form the vaginal plug may have contributed to the lesion. Correlation between development of the uropathy and diabetes has not been established.  (+info)

(5/6342) Spinal antinociceptive synergism between morphine and clonidine persists in mice made acutely or chronically tolerant to morphine.

Morphine (Mor) tolerance has been attributed to a reduction of opioid-adrenergic antinociceptive synergy at the spinal level. The present experiments tested the interaction of intrathecally (i.t.) administered Mor-clonidine (Clon) combinations in mice made acutely or chronically tolerant to Mor. ICR mice were pretreated with Mor either acutely (40 nmol i.t., 8 h; 100 mg/kg s.c., 4 h) or chronically (3 mg/kg s.c. every 6 h days 1 and 2; 5 mg/kg s.c. every 6 h days 3 and 4). Antinociception was detected via the hot water (52.5 degrees C) tail-flick test. After the tail-flick latencies returned to baseline levels, dose-response curves were generated to Mor, Clon, and Mor-Clon combinations in tolerant and control mice. Development of tolerance was confirmed by significant rightward shifts of the Mor dose-response curves in tolerant mice compared with controls. Isobolographic analysis was conducted; the experimental combined ED50 values were compared statistically against their respective theoretical additive ED50 values. In all Mor-pretreated groups, the combination of Mor and Clon resulted in significant leftward shifts in the dose-response curves compared with those of each agonist administered separately. In all tolerant and control groups, the combination of Mor and Clon produced an ED50 value significantly less than the corresponding theoretical additive ED50 value. Mor and Clon synergized in Mor-tolerant as well as in control mice. Spinally administered adrenergic/opioid synergistic combinations may be effective therapeutic strategies to manage pain in patients apparently tolerant to the analgesic effects of Mor.  (+info)

(6/6342) Comparison of local anesthetic activities between optical isomers of cis-1-benzoyloxy-2-dimethylamino-1,2,3,4-tetrahydronaphthalene.

The optical isomers of cis-1-benzoyloxy-2-dimethylamino-1,2,3,4-tetrahydronaphthalene (YAU-17) were compared for their local anesthetic activity, acute toxicity, spasmolytic activity, and partition coefficient between chloroform and phosphate buffer. 1-YAU-17 was more active than d-YAU-17 in blocking the conduction of action potentials in isolated frog sciatic nerves. The difference in local anesthetic activities between the optical isomers was further substantiated by in vivo tests for corneal anesthesia, intracutaneous anesthesia and sciatic nerve block in quinea-pigs. Similarly, the i.v. injection to mice revealed a higher toxicity for 1-YAU-17 as compared to its d-isomer. In these tests, the potency ratios of the enantiomers ranged from 2 to 4, and the racemate had an intermediate potency. On the contrary, no difference among the compounds was found in their liposolubility, partition coefficient, and spasmolytic activity examined with isolated guinea-pig ileum. These results indicate that the steric factors play an important role in the production of different local anesthetic activities between the optical isomers of YAU-17, and their local anesthetic potency tends to be correlated to their intravenous acute toxicity but not to their spasmolytic activity.  (+info)

(7/6342) Diperamycin, a new antimicrobial antibiotic produced by Streptomyces griseoaurantiacus MK393-AF2. I. Taxonomy, fermentation, isolation, physico-chemical properties and biological activities.

Antibacterial antibiotics, diperamycin (1) was produced in the culture broth of Streptomyces griseoaurantiacus MK393-AF2. Various spectroscopic analyses of 1 suggested that 1 belonged to a member of cyclic hexadepsipeptide antibiotic. Antibiotic 1 had potent inhibitory activity against various Gram-positive bacteria including Enterococcus seriolicida and methicillin-resistant Staphylococcus aureus.  (+info)

(8/6342) Uncoupling of in vivo torque production from EMG in mouse muscles injured by eccentric contractions.

1. The main objective of this study was to determine whether eccentric contraction-induced muscle injury causes impaired plasmalemmal action potential conduction, which could explain the injury-induced excitation-contraction coupling failure. Mice were chronically implanted with stimulating electrodes on the left common peroneal nerve and with electromyographic (EMG) electrodes on the left tibialis anterior (TA) muscle. The left anterior crural muscles of anaesthetized mice were stimulated to perform 150 eccentric (ECC) (n = 12 mice) or 150 concentric (CON) (n = 11 mice) contractions. Isometric torque, EMG root mean square (RMS) and M-wave mean and median frequencies were measured before, immediately after, and at 1, 3, 5 and 14 days after the protocols. In parallel experiments, nicotinic acetylcholine receptor (AChR) concentration was measured in TA muscles to determine whether the excitation failure elicited a denervation-like response. 2. Immediately after the ECC protocol, torque was reduced by 47-89 %, while RMS was reduced by 9-21 %; the RMS decrement was not different from that observed for the CON protocol, which did not elicit large torque deficits. One day later, both ECC and CON RMS had returned to baseline values and did not change over the next 2 weeks. However, torque production by the ECC group showed a slow recovery over that time and was still depressed by 12-30 % after 2 weeks. M-wave mean and median frequencies were not affected by performance of either protocol. 3. AChR concentration was elevated by 79 and 368 % at 3 and 5 days, respectively, after the ECC protocol; AChR concentration had returned to control levels 2 weeks after the protocol. At the time of peak AChR concentration in the ECC protocol muscles (i.e. 5 days), AChR concentration in CON protocol muscles was not different from the control level. 4. In conclusion, these data demonstrate no major role for impaired plasmalemmal action potential conduction in the excitation-contraction coupling failure induced by eccentric contractions. Additionally, a muscle injured by eccentric contractions shows a response in AChR concentration similar to a transiently denervated muscle.  (+info)