DNA mismatch repair status may influence anti-neoplastic effects of butyrate

HNPCC (hereditary non-polyposis colon cancer) is an autosomal-dominant disorder characterized by early-onset CRC (colorectal cancer). HNPCC is most often associated with mutations in the MMR (mismatch repair) genes hMLH1, hMSH2, hMSH6 or hPMS2. The mutator phenotype of a defective MMR system is MSI (microsatellite instability), which also occurs in approx. 15-25% of sporadic CRC cases, where it is associated with the hypermethylation of the promoter region of hMLH1. Dietary factors, including excessive alcohol consumption, ingestion of red meat and low folate intake, may increase the risk of MSI high tumour development. In contrast, aspirin may suppress MSI in MMR-deficient CRC cell lines. Butyrate, a short-chain-fatty-acid end product of carbohydrate fermentation in the colon, shares a number of anti-neoplastic properties with aspirin, including inhibiting proliferation and inducing apoptosis of CRC cells. Recent in vitro studies suggest that physiological concentrations of butyrate (0.5-2 mM) may have more potent anti-neoplastic effects in CRC cell lines deficient in MMR, but mechanisms for such a differential response remain to be established.

Folate and DNA methylation during in utero development and aging

DNA methylation is one of several epigenetic mechanisms that play a regulatory role in genome programming and imprinting during embryogenesis. Aberrant DNA methylation has been implicated in the pathogenesis of a number of diseases associated with aging, including cancer and cardiovascular and neurological diseases. Evidence is accumulating that dietary factors in utero modulate disease risk in later life. Although folic acid is a key component of DNA methylation, the impact of folic acid availability in utero on DNA methylation patterns and disease risk in adulthood is at present poorly characterized. This review describes the relationship between folic acid and DNA methylation, and the association between DNA methylation during in utero development and aging.

Differential distribution of parvalbumin immunoreactive neurons in the striatum of cocaine sensitized rats

Intermittent administration of psychostimulants such as cocaine and amphetamine can result in behavioral sensitization, which is believed to model the onset of drug addiction, as well as possible neural adaptations that lead to addictive behaviors. The dorsal striatum and the nucleus accumbens (NAc) have been shown to play an integral role in this phenomenon. However, these structures comprise a complex neuroanatomical organization, and few studies have correlated anatomical differentiation within these brain regions with functional (i.e. behavioral) outcome, particularly after psychostimulant exposure. Parvalbumin (PV)-containing GABAergic interneurons are a key neuronal cell population that can significantly regulate input-output functions in these brain regions. The present study quantified parvalbumin-immunoreactive cells in subterritories of the striatum and NAc in animals behaviorally sensitized to cocaine. Rats received a sensitization-inducing regimen of cocaine (twice-daily injections of 15 mg/kg i.p. for 5 consecutive days). Two or 14 days following the last injection, rats were given a challenge injection of cocaine (15 mg/kg i.p.), and killed 2 h later. Sections through the striatum (including the NAc) were processed for parvalbumin immunoreactivity, and the number of immunoreactive neurons was quantified. Repeated cocaine administration resulted in robust sensitization that correlated with transient increases in the number of PV immunoreactive neurons in the ventrolateral, dorsolateral and dorsomedial striatum. After a 2-week withdrawal period, sensitized animals showed a significant decrease in the number of PV+ neurons in the ventrolateral shell of the NAc and dorsomedial striatum, and no significant difference in any other area examined. These data suggest a dichotomous role for PV interneurons in different subterritories of the striatum and NAc during the short-term (induction) vs. long-term (expression) phases of cocaine sensitization.

Observation of the parametric two-ion decay instability with thomson scattering

We present the first direct experimental observation of the parametric two-ion decay instability of ion-acoustic waves driven by a high intensity (5 x 10(15) W cm(-2)) laser beam in a laser produced high-Z plasma. Using two separate Thomson scattering diagnostics simultaneously, we directly measure the scattering from thermal ion-acoustic fluctuations, the primary ion waves that are driven to large amplitudes by the high intensity beam, and the two-ion decay products. The decay products are shown to be present only where the interaction takes place and their k spectrum is broad.

Investigation of the onset and development of forward scattering in an underdense plasma

We investigate the distortion of a spatial intensity modulation imposed on a 527 nm f/10 probe beam as it transmits through an underdense plasma characterized with Thomson scattering. Combining the measurements with full wave simulations of beam propagation through the entire plasma show that the key features of the data can be reproduced using the Kaiser thermal transport model.

Observation of saturation of energy transfer between copropagating beams in a flowing plasma

Experiments demonstrate energy and power transfer between copropagating, same frequency, beams crossing at a small angle in a plasma with a Mach 1 flow. The process is interpreted as amplification of the low intensity probe beam by the stimulated scatter of the high intensity pump beam. The observed probe amplification increases slowly with pump intensity and decreases with probe intensity, indicative of saturation limiting the energy and power transfer due to ion-wave nonlinearities and localized pump depletion. The results are consistent with numerical modeling including ion-wave nonlinearities.

Anomalous absorption of high-energy green laser light in high- z plasmas

We observe strong anomalous absorption of green laser light in mm-scale high-temperature gold plasmas. Both the laser light absorption and the resulting increase of the electron temperature, which was measured independently with Thomson scattering, have been successfully modeled by including enhanced collisions due to heat-flux driven ion acoustic fluctuations. Calculations that include only inverse bremsstrahlung significantly underestimate the experimental laser absorption and the electron temperature.

Detection of red reflex asymmetry by pediatric residents using the Brückner reflex versus the MTI photoscreener

OBJECTIVE

To compare the ability of pediatric residents to differentiate an asymmetric from a symmetric red reflex in patients with anisometropia and microstrabismus using the Brückner reflex and the Medical Technology Innovations (MTI) photoscreener.

METHODS

A prospective, masked, case-control study was performed. Twelve pediatric residents evaluated 10 study patients and 6 control subjects in a masked manner in 2 separate sessions, using the Brückner reflex or the MTI photoscreener, evaluating for asymmetric (abnormal) or symmetric (normal) red reflexes between the 2 eyes. Each study patient had asymmetric red reflexes and the amblyogenic risk factor of anisometropia or microstrabismus. Each control subject had symmetric red reflexes.

RESULTS

The pediatric residents had a mean correct score of 82% (69%-100%) using the MTI photoscreener versus a mean correct score of 65% (44%-81%) using the Brückner reflex (McNemar test: alpha < 0.01). The sensitivity of the MTI photoscreener evaluation was 89% in comparison to 61% for the Brückner reflex. The specificities for the MTI photoscreener versus the Brückner reflex were similar at 69% and 71%, respectively.

CONCLUSIONS

Pediatric residents were better at detecting asymmetric red reflexes in patients with anisometropia and microstrabismus when evaluating MTI photoscreener photographs than when evaluating the red reflexes by the Brückner reflex. The MTI photoscreener may be a more sensitive method than the Brückner reflex to screen for the common amblyogenic risk factors of anisometropia and microstrabismus by easier detection of red reflex asymmetry.

Neurons of origin of the neurotensinergic plexus enmeshing the ventral tegmental area in rat: retrograde labeling and in situ hybridization combined

The morphological and physiological substrates that underlie the mutual regulatory interactions of neurotensin and dopamine in the rat mesotelencephalic projections and related structures remain to be fully described. A salient candidate for neurotensinergic effects on the mesotelencephalic dopamine projection is the dense plexus of neurotensin immunoreactive axons that enmeshes the ventral tegmental area and substantia nigra, but the locations of the neurons that give rise to this plexus have not been identified and its systemic context remains obscure. To address this, Fluoro-Gold and the cholera toxin beta subunit, retrogradely transported axonal tracers, were injected into the ventral tegmental area of rats and the brains were processed to demonstrate neurons that contained both retrograde tracer immunoreactivity and a probe against neurotensin/neuromedin N messenger RNA. Substantial numbers of double-labeled neurons were observed in the rostral part of the lateral septum, and in a region centered on the shared boundaries of the bed nucleus of stria terminalis, ventromedial ventral pallidum, diagonal band of Broca, lateral preoptic area and rostral lateral hypothalamus. A few double-labeled neurons were also observed in the dorsal raphe nucleus and adjacent periaqueductal gray. Despite the administration of haloperidol and D-amphetamine to elicit and enhance neurotensin/neuromedin N messenger RNA expression in striatum, including the nucleus accumbens and olfactory tubercle, no double-labeled neurons were observed there. These results identify a novel brain substrate for control of midbrain dopamine levels, which affect reward mechanisms and motivation.

Ventral mesopontine projections of the caudomedial shell of the nucleus accumbens and extended amygdala in the rat: double dissociation by organization and development

The shell of the nucleus accumbens and central division of the extended amygdala are telencephalic structures that influence motor activity and lately have been regarded by some as components of a single functional-anatomic continuum. Each has a highly differentiated internal organization and output system and distinct pharmacologic responses however, and it is thus likely that each subserves distinct contributions to behavior. In this investigation, nucleus accumbens and extended amygdala outputs were compared by using retrograde tracing in adult and postnatal rats. Fluoro-Gold, when injected into the ventral tegmental area, produced substantial retrograde labeling in the adult nucleus accumbens shell, but only trivial amounts in the central division of the extended amygdala. Injection sites in the lateral mesopontine tegmentum produced robust labeling in the central extended amygdala but little in the nucleus accumbens. The projections of extended amygdala were substantially developed by postnatal day 1, whereas those of the caudomedial shell of the nucleus accumbens only reached the ventral tegmental area by approximately postnatal day 6. Few neurons projecting from the caudomedial shell of the accumbens to the ventral tegmental area were observed even at postnatal day 21. In consideration of the reported importance of the nucleus accumbens, particularly the caudomedial shell, in neural processing related to reward and motivation and the central nervous system response to antipsychotic drugs, it may be important to determine whether processes occurring during the protracted postnatal development of the caudomedial shell are vulnerable to destructive circumstances, such as drug intoxication, maternal separation, or social isolation.

Liquid lung ventilation reduces neutrophil sequestration in a neonatal swine model of cardiopulmonary bypass

OBJECTIVE

Liquid lung ventilation has been demonstrated to improve cardiorespiratory function after cardiopulmonary bypass. We hypothesized that liquid lung ventilation (LLV) would decrease the pulmonary inflammatory response after cardiopulmonary bypass (CPB).

DESIGN

Prospective, randomized, experimental, controlled, nonblinded study.

SETTING

Animal research laboratory at a university setting.

SUBJECTS

A total of 24 neonatal piglets.

INTERVENTIONS

After intubation with a cuffed endotracheal tube, swine were conventionally ventilated. After surgical cannulation, each piglet was placed on conventional nonpulsatile CPB and cooled to 18 degrees C (64.4 degrees F). Subsequently, the animals were exposed to 90 mins of low-flow CPB (35 mL/kg/min). Animals were rewarmed to 37 degrees C (98.6 degrees F), removed from CPB, and ventilated for 90 min. Ten animals received conventional gas ventilation only (control), seven received initiation of LLV before CPB (prevention), and seven received initiation of LLV during the rewarming phase of CPB (treatment). After the animals were killed, the lungs were removed en bloc. The left lobe was dissected and formalin-fixed at 20 cm H2O overnight, followed by paraffin embedding. Sections were taken from the paraffin-embedded lungs. Neutrophil accumulation and lung injury were assessed by histochemical staining with leukocyte esterase and morphometrics, respectively. One hundred microscopic images were digitized from each tissue sample for lung morphometrics, and neutrophil counts were obtained from every fifth image.

MEASUREMENTS AND MAIN RESULTS

Lung tissue sections showed a significantly lower number of neutrophils per alveolar area in the prevention and treatment groups than in the control group (control 681 +/- 65, prevention 380 +/- 49, treatment 412 +/- 101 neutrophils per alveolar area [cells/mm2]; p <.05 for both prevention and treatment compared with control). There were no differences in lung injury as assessed with morphometrics or hemodynamic measurements between any of the three groups.

CONCLUSIONS

The data suggest that LLV reduces the CPB-induced neutrophil sequestration in the pulmonary parenchyma independent of its effects on the circulatory physiology or evidence of early lung injury.

Backscatter reduction using combined spatial, temporal, and polarization beam smoothing in a long-scale-length laser plasma

Spatial, temporal, and polarization smoothing schemes are combined for the first time to reduce to a few percent the total stimulated backscatter of a NIF-like probe laser beam (2x10(15) W/cm (2), 351 nm, f/8) in a long-scale-length laser plasma. Combining temporal and polarization smoothing reduces simulated Brillouin scattering and simulated Raman scattering (SRS) up to an order of magnitude although neither smoothing scheme by itself is uniformly effective. The results agree with trends observed in simulations performed with the laser-plasma interaction code F3D simulations [R. L. Berger et al., Phys. Plasma 6, 1043 (1999)].

Thomson scattering measurements of saturated ion waves in laser fusion plasmas

We have measured the characteristics of saturated ion-acoustic waves in inertial confinement fusion plasmas. A 263-nm probe laser has been applied to simultaneous Thomson scatter on both ion-acoustic waves excited by thermal electrostatic fluctuations and by stimulated Brillouin scattering of a kilojoule laser beam of varying intensity. The Thomson scattering spectra show saturated ion-wave amplitudes for intensities above 5x10(14) W cm(-2) consistent with three dimensional nonlinear wave modeling.

On the altered expression of tyrosine hydroxylase and calbindin-D 28kD immunoreactivities and viability of neurons in the ventral tegmental area of Tsai following injections of 6-hydroxydopamine in the medial forebrain bundle in the rat

Calbindin-D 28kD is a calcium binding protein reported to protect neurons from degeneration by buffering intracellular calcium. It is expressed in midbrain dopaminergic neurons reported to be relatively resistant to degeneration in Parkinson's disease and certain of its animal models. Lesions of the nigrostriatal pathway produced in rats following injection of 6-hydroxydopamine result in a neurochemical profile similar to that seen in patients with Parkinson's disease. In the present study, brains were processed to exhibit tyrosine hydroxylase- and calbindin-D 28kD immunoreactivities in sections through the ventral mesencephalon at 3, 7, 10, 14 and 21 days after 6-hydroxydopamine had been injected into the medial forebrain bundle. Numbers of ventral mesencephalic calbindin-D 28kD immunoreactive neurons were significantly reduced ipsilateral to the lesions at 3 days post-lesion and, following slight recovery, remained significantly depleted through post-lesion day 21. The densities of calbindin-D 28kD and tyrosine hydroxylase immunoreactive neurons were different only at the 3 day post-lesion time point, when the apparent loss of calbindin-D 28 kD immunoreactive profiles was significantly greater. A lesion-induced increase in the proportion of neurons exhibiting both calbindin-D 28kD and tyrosine hydroxylase immunoreactivities, expected if calbindin-D 28kD is neuroprotective, was observed in the substantia nigra, pars compacta, but not in the ventral tegmental area. It is concluded that, while the observed losses of tyrosine hydroxylase and calbindin-D 28kD immunoreactivities do not necessarily reflect neuronal degeneration, they are not consistent with CB confering a neuroprotective advantage in the ventral tegmental area following 6-OHDA lesions as administered in this study.

Acute lung injury and acute respiratory distress syndrome after pulmonary resection

BACKGROUND

In this study we investigate the frequency and mortality of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) after pulmonary resection.

METHODS

Patients that underwent pulmonary resection at the Royal Brompton Hospital between 1991 and 1997 were included. The case notes of all patients developing postoperative complications were retrospectively reviewed.

RESULTS

The overall combined frequency of ALI and ARDS was 3.9%. The frequency was higher in patients over 60 years of age, males and those undergoing resection for lung cancer. ALI/ARDS caused 72.5% of the total mortality after resection in this series.

CONCLUSIONS

In our experience ALI and ARDS are major causes of mortality after lung resection.

Lung injury following pulmonary resection in the isolated, blood-perfused rat lung

Lung resection may be complicated by postpneumonectomy pulmonary oedema. Oxidant generation following surgery-induced ischaemia-reperfusion may be responsible. This hypothesis was tested utilizing isolated, in situ, blood perfused rodent lungs subjected to continuous perfusion (control subjects); one lung ventilation followed by pneumonectomy (group 1); or one lung ventilation followed by reinflation of the collapsed lung (group 2). In control subjects, no significant changes in markers of oxidant damage, oxygenation, pulmonary artery pressure or extravascular albumin extravasation were detected. In group 1 lungs, hydroxyl radical-like damage was detected in association with impaired oxygenation (p<0.05), and increased pulmonary artery pressure and extravascular albumin accumulation in both lungs. In group 2, there was evidence of hydroxyl radical-like damage, and a fall in oxygenation (p<0.05) occurred during one lung ventilation. There was a transient rise in pulmonary artery pressure following lung reinflation and extra vascular albumin accumulation was significantly increased in both lungs (right>left, p<0.05). Both changes were attenuated (p<0.05) following treatment with the reactive oxygen species (ROS) scavenger superoxide dismutase (group 2a) and the nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester (group 2b). Hydroxyl radical-like damage was undetectable following nitric oxide synthase inhibition. Oxidant stress may contribute to the pathologies seen in this model of lung injury.

Perforin-dependent nuclear entry of granzyme B precedes apoptosis, and is not a consequence of nuclear membrane dysfunction

Killer lymphocytes utilize the synergy of a membranolytic protein, perforin, and the serine protease granzyme B (grB) to induce target cell apoptosis, however the mechanism of this synergy remains incompletely defined. We have previously shown that perforin specifically induces the redistribution of cytoplasmic grB into the nucleus of dying cells, however a causal role for nuclear targeting of grB in cell death has not been demonstrated. In the present study, we used confocal laser scanning microscopy (CLSM) to determine whether the nuclear accumulation of fluoresceinated (FITC-) grB precedes or is a consequence of apoptosis. Two distinct and mutually exclusive cellular responses were observed in FDC-P1 cells: (i) up to 50% of the cells rapidly accumulated FITC-grB in the nucleus (maximal at 7 min; t1/2 of 2 min) and underwent apoptosis; (ii) the remaining cells took up FITC-grB only into the cytoplasm, and escaped apoptosis. Under these conditions, DNA fragmentation was not observed for at least 13 min, indicating nuclear accumulation of grB preceded the execution phase of apoptosis. Furthermore, nuclear import of grB proceeded through an intact nuclear membrane, as the nuclei of cells whose cytoplasm was pre-loaded with 70 kDa FITC-dextran excluded dextran for up to 90 min while still undergoing apoptosis in response to perforin and grB. These findings indicated that perforin-induced nuclear accumulation of grB precedes apoptosis, and is not a by-product of caspase-induced nuclear membrane degradation. The cell membrane lesions formed by perforin in these experiments were not large enough to permit a 13 kDa protein (yeast cdk p13suc) access into the cytoplasm, but an 8 kDa protein (bacterial azurin) was able to equilibrate between the cytosol and the exterior. Therefore, transmembrane pores large enough to allow passive diffusion of grB (32 kDa) into the cell are not necessary for apoptosis. Rather, a perforin-dependent signal results in a redistribution of grB from the cytoplasm to the nucleus, where it may contribute to the nuclear changes associated with apoptosis.

Postoperative lung injury and oxidative damage in patients undergoing pulmonary resection

Postpneumonectomy pulmonary oedema (PPO) complicates a significant number of thoracic surgical procedures involving lung resection and in its extreme form is indistinguishable from the acute respiratory distress syndrome. This study investigated the possibility that ischaemia-reperfusion (I-R) injury contributes to PPO via the production of damaging reactive oxygen species. In a prospective, observational, comparative study, patients undergoing pneumonectomy, lobectomy, or wedge resection or open lung biopsy were investigated for perioperative changes in lung function indicative of lung injury and changes in plasma indices of oxidative damage. Significant percentage perioperative falls in plasma protein thiol levels (-17.9+/-7.0% for pneumonectomy, -24.3+/-5.5% for two-lobe lobectomy and -10.2+/-2.2% for one-lobe lobectomy, p<0.05) and rises in plasma protein carbonyl levels (26.2+/-10.5% for pneumonectomy, p<0.05, 9.8+/-7.0% for two-lobe lobectomy and 5.0+/-2.7% for one-lobe lobectomy) were identified, but not in patients undergoing biopsy or wedge resection. Plasma myeloperoxidase levels rose in all groups, but not significantly. The carbon monoxide transfer coefficient (K(CO)) fell significantly in patients undergoing lobectomy (p<0.05) but not in those undergoing wedge resection, lung biopsy or pneumonectomy. Changes in markers of oxidative protein damage occurred in patients undergoing lung resection, although the gas transfer coefficient fell significantly only following lobectomy. Oxidative damage occurs during pulmonary resection, although associated effects on gas exchange are seen only after lobectomy.

Sexual coercion, domestic violence, and negotiating condom use among low-income African American women

Coercion to engage in unwanted sex places women at risk for human immunodeficiency virus (HIV) infection. A survey of 125 women living in low-income housing developments in Fulton County, Georgia, showed that 53 (42%) women had engaged in unwanted sex because a male partner threatened to use force or used force to obtain sexual access. Women who had been sexually coerced were more likely to have used marijuana and crack cocaine and to have abused alcohol. Coerced women were more likely to have been physically abused by a domestic partner. These women were also more likely to perceive that requesting male partners to use condoms would create a potentially violent situation. These results suggest that women experience an interactive constellation of social problems that create risks for HIV infection and, therefore, that efforts to prevent HIV infection among women will require multifaceted intervention strategies to reach both men and women at risk.

It's like a regular part of gay life: repeat HIV antibody testing among gay and bisexual men

HIV antibody testing is a critical facet of national AIDS prevention strategies and increasing numbers of persons are tested each year. Research has shown that a significant number of men who have sex with men are repeatedly tested for HIV antibodies, and many are tested regularly every 6 months. This study investigated the prevalence of repeat testing (having been tested three or more time) and regular testing (having been tested three or more times and getting tested every 6 months), and their association to testing attitudes and sexual behaviors. We found that 66% of 253 HIV seronegative gay and bisexual men surveyed at a large gay pride festival had been repeatedly tested, and 47% were tested regularly. Repeat testing was associated with knowing people with HIV or AIDS, whereas regular testing was associated with younger age and not being in an exclusive sexual relationship. Both repeat and regular testers held more positive health-related attitudes about testing than nonrepeat and nonregularly tested men, respectively. Contrary to previous research, repeat testing was not associated with unprotected anal intercourse or unprotected oral sex. However, both repeat and regular testing were positively related to condom use during anal intercourse as well as having multiple protected anal intercourse partners. We therefore conclude that both repeat testing and higher rates of condom use reflect positive health attitudes and that repeat testing may function to meet the needs of some men who have sex with men.

An investigation into the reversibility of the morphological and cytokinetic changes seen in the small intestine of riboflavin deficient rats

BACKGROUND

Impaired iron handling in riboflavin deficiency is thought to be partially a result of significant morphological and cytokinetic changes within the small intestine.

AIMS

The aim of the study was to find out if the responses of the rat small intestine to riboflavin deficiency induced at weaning could be reversed upon repletion.

SUBJECTS

48 female weanling Wistar rats were used for the purpose of the study.

METHODS

Rats were fed a riboflavin deficient diet or a complete control diet for a period of five weeks followed by a repletion period of up to three weeks. Rats were killed on day 0, 2, 7, or 21 of repletion. The duodenum was removed and fixed for subsequent analysis.

RESULTS

Five weeks of riboflavin deficiency significantly changed the morphology and cytokinetics of the duodenum; the changes were not reversed within the 21 day repletion period despite biochemical evidence for a correction of the deficiency.

CONCLUSIONS

The results show that the small intestine cannot readily recover from a period of riboflavin deficiency induced at weaning, supporting the notion that the weaning period is a critical time for gastrointestinal development and highlighting the importance of adequate nutrition during infancy.