Increased transversions in a novel mutator colon cancer cell line

We describe a novel mutator phenotype in the Vaco411 colon cancer cell line which increases the spontaneous mutation rate 10-100-fold over background. This mutator results primarily in transversion base substitutions which are found infrequently in repair competent cells. Of the four possible types of transversions, only three were principally recovered. Spontaneous mutations recovered also included transitions and large deletions, but very few frameshifts were recovered. When compared to known mismatch repair defective colon cancer mutators, the distribution of mutations in Vaco411 is significantly different. Consistent with this difference, Vaco411 extracts are proficient in assays of mismatch repair. The Vaco411 mutator appears to be novel, and is not an obvious human homologue of any of the previously characterized bacterial or yeast transversion phenotypes. Several hypotheses by which this mutator may produce transversions are presented.     

Benign solitary fibrous tumour of the pre-sacral space: MRI findings

Benign solitary fibrous tumour, a rare mesenchymal tumour of adults, usually arises from the pleura. Only a few cases have been reported in the retroperitoneum and, to our knowledge, there has been no report of its imaging features. We describe the MRI features of benign solitary fibrous tumour arising from the pre-sacral space.     

Confirmation of the human-pathogenic microsporidia Enterocytozoon bieneusi, Encephalitozoon intestinalis, and Vittaforma corneae in water

Microsporidia, as a group, cause a wide range of infections, though two species of microsporidia in particular, Enterocytozoon bieneusi and Encephalitozoon intestinalis, are associated with gastrointestinal disease in humans. To date, the mode of transmission and environmental occurrence of microsporidia have not been elucidated due to lack of sensitive and specific screening methods. The present study was undertaken with recently developed methods to screen several significant water sources. Water concentrates were subjected to community DNA extraction followed by microsporidium-specific PCR amplification, PCR sequencing, and database homology comparison. A total of 14 water concentrates were screened; 7 of these contained human-pathogenic microsporidia. The presence of Encephalitozoon intestinalis was confirmed in tertiary sewage effluent, surface water, and groundwater; the presence of Enterocytozoon bieneusi was confirmed in surface water; and the presence of Vittaforma corneae was confirmed in tertiary effluent. Thus, this study represents the first confirmation, to the species level, of human-pathogenic microsporidia in water, indicating that these human-pathogenic microsporidia may be waterborne pathogens.     

The role of enterocytes in gut dysfunction

Stem cells in the intestinal epithelium give rise to enterocytes, goblet cells, enteroendocrine cells, and Paneth cells. Each of these cell lines plays a role in cytoprotection of the intestinal mucosa. In particular, it has been demonstrated that mature enterocytes can act as antigen presenting cells. Parenteral and enteral nutrition are used to nourish critically ill patients. However, these regimens are unfortunately associated with gut atrophy. Glutamine, the preferred intestinal nutrient, reverses this gut atrophy and plays a key role in maintaining the barrier function of the gut. Specific nutrients (putrescine, spermidine, spermine) have been used to modulate intestinal adaption. In addition, ornithine has been shown to act as a regulator of intestinal adaption. In this review, we discuss the relationship between the biology of enterocytes and failure of the gut barrier.     

Comparison of wound culture and bronchial lavage in the severely burned child: implications for antimicrobial therapy

BACKGROUND: The relationship of the burn wound flora to microbial pathogens in the tracheobronchial tree has important implications for antimicrobial therapy in the severely burned patient. Management of septic complications is bolstered by surveillance quantitative wound cultures (QWC) and bronchial lavage fluid (BLF) cultures. OBJECTIVES: To compare the organisms present in BLF with those found in QWC and to determine if QWC can predict BLF results. DESIGN: Results of BLF cultures from all patients who underwent bronchial lavage from January 1, 1996, to December 31, 1996, at our institution were compared with QWC data from the same date. Criteria for a positive match included an identical antibiotic susceptibility pattern and biotype. Match rates were calculated qualitatively and quantitatively. RESULTS: In 30 (48%) of the 62 BLF cultures, there was a match between the organism identified in the BLF and the QWC. When strict quantitative criteria were applied, the match rate was only 9 (14%) of 62. Burn size and inhalation injury had no significant effect on match rate. CONCLUSIONS: Whereas the microbial pathogens were similar in the QWC and BLF, linear regression showed no value of QWC in predicting BLF culture results. The difference between qualitative and quantitative match rates suggests cross-colonization between the burn wound and tracheobronchial tree, but little to no cross-infection. The QWC and BLF cultures must be performed independently in determining antimicrobial specificity in the burned patient.     

Surface structure of human mucin using X-ray photoelectron spectroscopy

The stimulating effect of antiparkinsonian drugs, talipexole and bromocriptine, on the striatal postsynaptic dopamine receptors were studied by measuring contralateral rotational behavior in rats. The nigro-striatal dopamine system of rats was degenerated by unilateral injection of 6-hydroxydopamine (6-OHDA, 8 micrograms/rat) into substantia nigra. By subcutaneous administration, talipexole at 0.16 mg/kg and bromocriptine at 10.24 mg/kg induced significantly increased rotational behavior to the contralateral direction to the lesioned side. The onset of the effect was 30 min for talipexole and 90 min for bromocriptine. By intragastric administration, talipexole at 0.4 mg/kg and bromocriptine at 20.48 mg/kg significantly increased the rotational behavior, and the onset of the effect was 60 min for talipexole and 180 min for bromocriptine. Rotational behavior induced by talipexole was suppressed by a D2 antagonist, sulpiride (40 mg/kg, s.c.), but not by a D1 antagonist, SCH23390 (1 mg/kg, s.c.). In contrast, rotational behavior induced by bromocriptine was suppressed by both sulpiride and SCH23390. These results indicated that when the nigrostriatal dopaminergic functions are disrupted, talipexole stimulates the striatal postsynaptic dopamine receptors at much lower doses than bromocriptine. Also it was indicated that the stimulating effect of talipexole is solely mediated by dopamine D2 receptors, whereas the effect of bromocriptine is mediated by both D1 and D2 receptors.     

The role of IL-4, IL-10, and TNF-alpha in the immune suppression induced by ultraviolet radiation

The two main catalytic residues Cys25 and His159 of the monomeric cysteine protease papain are located on different walls of a cleft formed by two domains. This topology suggests a possible relationship between relative domain organization and catalytic mechanism. The effect on enzymatic parameters of structural modifications at various locations of the two-domain interface of papain was examined by individual or double replacements by Ala of pairs of interacting residues. Most modifications had no effect on enzyme activity. However, the enzyme's substrate turnover (kcat) decreased following simultaneous alteration of the two most conserved residues, forming an apolar contact located 15 A away from the active site. The pH activity profile of the double mutant was unchanged, indicating a conserved ionization state of the active site thiolate-imidazolium ion pair. This state is strongly dependent on the distance separating the two residues, thus suggesting that the active site geometry has not been significantly altered. Efficient enzymatic activity in papain requires more than a correct active site geometry and is influenced by domain packing properties in a region remote from the active site.     

Hematocrit values in weight-selected and relaxed lines of White Rock chickens

Hematocrits (PCV) were measured at 29 and 106 d of age (PCV1 and PCV2, respectively) in male and female White Plymouth Rocks. Four lines were used, two of which had undergone 40 generations of divergent selection for 8-wk BW (HWS, LWS), and two respective sublines (HWR, LWR), in which selection had been relaxed for five generations. At both ages, males and females did not differ for PCV in lines HWR, LWR, and LWS. For line HWS there was an age by sex interaction that resulted from an age effect for males but not for females, and from a sex effect at each age. At both ages, PCV was higher for the HW than the LW lines. Initially, there was no difference between the selected and their respective relaxed lines, but by 106 d, HWR chickens had a higher PCV than HWS chickens. In lines HWR and LWR, PCV increased with age. There was a negative correlation in HWS males for PCV1 with 28 and 56 d BW. The HWR males also had a negative correlation for PCV1 with BW at 28 d, but not between PCV2 and BW. The correlation for PCV1 with PCV2 was high and positive for HWR males and females.     

A PC-based software test for measuring alcohol and drug effects in human subjects

A new software-based visual search and divided-attention test of cognitive performance was developed and evaluated in an alcohol dose-response study with 24 human subjects aged 21-62 years. The test used language-free, color, graphic displays to represent the visuospatial demands of driving. Cognitive demands were increased over previous hardware-based tests, and the motor skills required for the test involved minimal eye movements and eye-hand coordination. Repeated performance on the test was evaluated with a latin-square design by using a placebo and two alcohol doses, low (0.48 g/kg/LBM) and moderate (0.72 g/kg/LBM). The data on 7 females and 17 males yielded significant falling and rising impairment effects coincident with moderate rising and falling breath alcohol levels (mean peak BrALs = 0.045 g/dl and 0.079 g/dl). None of the subjects reported eye-strain or psychomotor fatigue as compared with previous tests. The high sensitivity/variance relative to use in basic and applied research, and worksite fitness-for-duty testing, was discussed. The most distinct advantage of a software-based test that operates on readily available PCs is that it can be widely distributed to researchers with a common reference to compare a variety of alcohol and drug effects.