Protective effect of RibCys following high-dose irradiation of the rectosigmoid

Ribose-cysteine (RibCys) is a prodrug of L-cysteine that stimulates glutathione biosynthesis. Increased glutathione levels have been shown to have a protective effect against radiation-induced injury and oxidative stress. Surface oximetry has previously been used successfully to predict anastomotic leakage. PURPOSE: The following study was done to evaluate the protective effect of RibCys and the predictive value of PtO2 determinations in a swine model. METHODS: Domestic swine were divided into three groups: Group A served as a nonradiated control; Group B received 6,000 to 6,500 rad to the rectosigmoid; and Group C received RibCys (1 g/kg) prior to receiving 6,000 to 6,500 rad. Radiated animals and controls underwent rectosigmoid resection after a three-week rest period. Intraoperative anastomotic PtO2 was checked with a modified Clark electrode. Anastomoses were evaluated radiographically at three and seven days; animals were sacrificed, and bursting strength was recorded at 10 days. RESULTS: Mean bursting pressures were 243.8 +/- 59.4, 199.5 +/- 37.8, and 209.5 +/- 54.9 mmHg (NS) for Groups A, B, and C, respectively. Anastomotic PtO2 ranged from 19 to 98 mmHg and could not be correlated with anastomotic leaks or bursting pressure. There were 11/15 radiation-related deaths and leaks (eight deaths and three leaks) in the radiated group and 4/12 radiation-related deaths and leaks (three deaths and one leak) in the group receiving radiation and RibCys (P < 0.04). CONCLUSIONS: 1) RibCys protected animals against radiation-related deaths and anastomotic leaks following high doses of pelvic irradiation; 2) anastomotic PtO2 levels did not correlate with anastomotic healing in this model.     

Differential effects of nerve impulses on adrenergic storage vesicles in rat heart

The effects of increasing and decreasing activity in sympathetic neurons on light (D420 = 1.05) and heavy (D420 = 1.15) populations of adrenergic vesicles have been determined. Norepinephrine (NE) was used as a marker for the soluble contents of the vesicles, and dopamine beta-hydroxylase was used as a marker for the vesicle membranes. Cold exposure was used to increase activity in the sympathetic nervous system. A 40% decrease in the NE content of the rat heart with no change in the activity of dopamine beta-hydroxylase was observed after 70 minutes at 5 degrees C. The fall in NE content was completely blocked by pretreating the animals with chlorisondamine. Separation of light and heavy populations of vesicles was achieved with linear sucrose density gradients. Cold stress of 70 minutes duration led to a marked decrease in the NE content of the light vesicles. Blocking adrenergic nerve impulses with chlorisondamine resulted in an increase in total NE in the heart but had no effect on dopamine beta-hydroxylase activity. The initial effect of chlorisondamine was to increase the NE content of the light vesicles. The administration of alpha-methyl-p-tyrosine for 6 hours caused an approximately equal loss of NE from both vesicle populations. The decrease in total heart NE was about 25% and could be prevented by pretreating the animals with chlorisondamine. These results suggest that the light vesicle fraction is involved in the rapid or short-term responses to changes in nerve impulse frequency. Changes in the NE content of the heavy vesicles in rat heart were seen only after longer times, suggesting that these particles may function only as auxiliary storage sites for the neurotransmitter.     

Modification of the standard method used in the United Kingdom for counting Escherichia coli in live bivalve molluscs

Surgical fusion of the subtalar, talonavicular, and calcaneocuboid joints historically evolved for the treatment of paralytic deformities of the foot where there was often notable bone deformity. Today most of these procedures are performed in adults for posttraumatic arthritis, rheumatoid arthritis, or end-stage posterior tibial tendon rupture with fixed bone deformity. Triple arthrodesis is a technically demanding procedure that generally involves a prolonged recovery time. When proper alignment is obtained, predictable and significant improvement in symptoms occurs, but the resultant loss of hindfoot motion is not without consequence. Residual discomfort and secondary arthrosis of the ankle and tarsometatarsal joints should be expected. Because of the complications of residual deformity, pseudarthrosis, avascular necrosis of the talus, and ankle and midtarsal arthritis, it has been recommended that it be used only as a salvage operation in older patients who have a painful, fixed deformity or disabling instability refractory to other treatment options. Despite these caveats, most patients who undergo triple arthrodesis for appropriate indications report significant improvement in their symptoms and level of function.     

Foraging on the radial maze: The role of travel time, food accessibility, and the predictability of food location.

Reports on an experiment in which rats foraged in a 4-arm radial maze containing 4 feeders in each arm, with different percentages of baited feeders in each arm (0%, 25%, 50%, or 75%). The effects of three variables were examined: (1) Arm entrances were open or blocked to increase travel time between arms; (2) Feeders were uncovered or covered to decrease accessibility to food; (3) Food locations were randomly changed between sessions or remained fixed. Rats learned to discriminate between the 0% arm and arms containing food when food locations were fixed but not when food locations were random. Rats also learned the locations of baited feeders within arms with fixed food locations, but selectively visited baited feeders only if the feeders were covered. Comparisons of obtained data with computer simulations indicated that rats foraged near optimality. Patterns of foraging were best accounted for by a molecular maximizing model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

GaAs/LB film MISS switching device

MISS switches incorporating Langmuir-Blodgett films as insulating layers are reported for the first time. Devices fabricated using n on p+ GaAs and including a 9 nm-thick ?-tricosenoic acid insulating layer are shown to possess good characteristics. The results indicate that switching occurs due to a `punch-through? mechanism.     

Inflammatory response of the spinal cord to multiple episodes of blood-brain barrier disruption and toxic demyelination in Wistar rats

Multiple episodes of blood-brain barrier disruption were induced by sequential intraspinal injections of ethidium bromide. In addition to the barrier disruption, there was toxic demyelination and exposure of myelin components to the immune system. Twenty-seven 3-month-old Wistar rats received 2, 3 or 4 injections of 1 microliter of either 0.1% ethidium bromide in normal saline (19 rats) or 0.9% saline (8 rats) at different levels of the spinal cord. The time intervals between the injections ranged from 28 to 42 days. Ten days after the last injection, all rats were perfused with 2.5% glutaraldehyde. The spinal sections were evaluated macroscopically and by light and transmission electron microscopy. All the lesions demonstrated a mononuclear phagocytic infiltrate apparently removing myelin. Lymphocytes were not conspicuous and were found in only 34% of the lesions. No perivascular cuffings were detected. In older lesions (38 days and older) they were found only within Virchow-Robin spaces. This result suggests that multiple blood-brain barrier disruptions with demyelination and exposure of myelin components to the immune system were not sufficient to induce an immune-mediated reaction in the central nervous system.     

Synthesis and serotonin receptor affinities of a series of trans-2-(indol-3-yl)cyclopropylamine derivatives

A series of four racemic ring-substituted trans-2-(indol-3-yl)cyclopropylamine derivatives was synthesized and tested for affinity at the 5-HT1A receptor, by competition with [3H]-8-OH-DPAT in rat hippocampal homogenates, and for affinity at the agonist-labeled cloned human 5-HT2A, 5-HT2B, and 5-HT2C receptor subtypes. None of the compounds had high affinity for the 5-HT1A receptor, with the 5-methoxy substitution being most potent (40 nM). At the 5-HT2A and 5-HT2B receptor isoforms, most of the compounds lacked high affinity. At the 5-HT2C receptor, however, affinities were considerably higher. The 5-fluoro-substituted compound was most potent, with a Ki at the 5-HT2C receptor of 1.9 nM. In addition, the 1R,2S-(-) and 1S,2R-(+) enantiomers of the unsubstituted compound were also evaluated at the 5-HT2 isoforms. While the 1R,2S enantiomer had higher affinity at the 5-HT2A and 5-HT2B sites, the 1S,2R isomer had highest affinity at the 5-HT2C receptor. This reversal of stereoselectivity may offer leads to the development of a selective 5-HT2C receptor agonist. The cyclopropylamine moiety therefore appears to be a good strategy for rigidification of the ethylamine side chain only for tryptamines that bind to the 5-HT2C receptor isoform.