The role of specific DNA adducts in the induction of micronuclei by N-hydroxy-2-acetylaminofluorene in rat liver in vivo

N-Hydroxy-Z-acetylaminofluorene (N-OH-AAF) was administeredi.p. to male Wistar rats 17 h after partial hepatectomy. Hepatocyteswere analyzed for the presence of micronuclei 7 h, 1, 2, 3 and4 days after injection. N-OH-AAF treatment resulted in a highfrequency of micronucleated hepatocytes at days 3 and 4 (19.5and 19.6 respectively). The frequency of micronucleated hepatocyteswas not increased above control values when hepatocytes wereisolated as early as 7 h, 1 or 2 days after injection. Pretreatmentwith the sulfotransferase inhibitor pentachlorophenol (PCP)45 min before injection of N-OH-AAF almost completely preventedthe formation of micronuclei by N-OH-AAF. Parallel biochemicalstudies indicated that inhibition of sulfation of N-OH-AAF byPCP pretreatment prevented the formation of the N-acetylatedDNA adducts iV-deoxyguanosin-8-yl-AAF and 3-deoxyguanosin-N²-yl-AAFby {small tilde}85%. Total adduct formation to DNA was, however,not lowered because of an increase in the formation of the deacetylatedadduct, N-deoxy-guanosin-8-yl-AAF. The lower frequency of micronucleatedhepatocytes observed in the group pretreated with PCP, did notresult from less proliferative activity in this group as comparedto the group treated with N-OH-AAF alone. Therefore, the decreasein the formation of micronuclei indicates that PCP preventsthe clastogenic damage caused by N-OH-AAF. It is concluded thatthe clastogenicity of N-OH-AAF in rat liver is related to theformation of N-acetylated DNA adducts (i.e. N-deoxyguanosin-8-yl-AAFand/or 3-deoxy-guanosin-N²-yl-AAF) and is not related to theformation of the deacetylated DNA adduct N-deoxyguanosin-8-yl-AF.     

High prevalence of human papillomavirus infections in urine samples from human immunodeficiency virus-infected men

Infection with human immunodeficiency virus (HIV) and the resulting immunosuppression are associated with an increased risk for human papillomavirus (HPV) persistence and related malignancies. In the present study we investigated the prevalence of HPV in urine samples from 104 HIV-infected men with low CD4+ cell counts (<100 per mm(3)) and 115 urine samples from HIV-negative men. A high prevalence of HPV DNA (39.4%) was found in the HIV patients. Most of the HPV types were high risk (81.4%), with HPV 52 as the most prevalent type (12.5%), followed by HPV 18 (6.7%), HPV 35 (5.8%), and HPV 70 (4.8%). Multiple HPV genotypes were observed in 17 (41%) of the 41 HPV- and HIV-positive men. In contrast, only 11 (9.6%) HPV DNA-positive cases were observed among the 115 HIV-uninfected men, and 3 (27.3%) contained multiple genotypes. Quantitative analyses indicated that the HPV viral load, as measured in urine samples, is significantly higher in HIV-positive men compared to HIV-negative men. In the present study we show that urine samples are useful for detecting HPV DNA, there is a high prevalence of HPV in HIV-positive men, and the HPV viral load is substantially higher in HIV-positive than in HIV-negative men. More studies are needed to evaluate the risk and natural development of HPV-related malignancies in HIV-positive men.     

Attention to Color: An Analysis of Selection, Controlled Search, and Motor Activation, Using Event-Related Potentials

In this study the organization of information processing in a selective search task was examined by analyzing event-related potentials. This task consisted of searching for target letters in a relevant (attended) color. The ERPs revealed two different effects of attention: an early occipital negativity (+/- 150 ms) reflecting feature-specific attention, and a later, central N2b component (+/- 240 ms) reflecting covert orienting of attention. A later, prolonged negativity (search-related negativity) (+/- 300 ms), maximal at Cz, was related to controlled search to letters in the attended color. Detection of relevant targets resulted in a parietal P3b component. Depending on stimulus presentation conditions an earlier response to both attended and unattended targets was found: an N2 component (+/- 250 ms). In these same conditions, C'3-C'4 asymmetries (Corrected Motor Asymmetries--CMA) suggested motor activation at +/- 300 ms, in the same time range as search-related negativity. It was argued that N2 and CMA suggest the existence of a preattentive target detection system, operating in parallel with a slower serial attentive system, as reflected by N2b and search negativity.     

Characterization of monocyte maturation in adherent and suspension cultures and its application to study monocyte differentiation in Hodgkin's disease.

Monocytes purified with cell scatter monitored counterflow centrifugation were cultured in plastic (adherent) and in teflon culture bags (suspension). Sequential changes were monitored during 15 days by measuring intracellular activity of three enzymes of intermediary metabolism: glucose-6-phosphate dehydrogenase (G-6-PDH), phosphohexose isomerase (PHI) and isocitrate dehydrogenase (ICDH), and the two acid hydrolases: acid phosphatase (ACP) and N-acetyl-beta-glucosaminidase (NAG). In teflon grown macrophages a significantly lower G-6-PDH activity was seen after 15 days in comparison to plastic adherent macrophages (P less than 0.0002). For the other enzymes similar values for both culture modalities were found. The significantly, cycloheximide insensitive, higher values for G-6-PDH, PHI and ICDH in 2 h plastic adherent monocytes in comparison with plastic non-adherent monocytes, suggest a relationship between adherent capacity and the level of intermediary metabolism. The overall yield of plastic adherent macrophages after 15 days was 35% in contrast with 89% for the in suspension cultured macrophages. This corroborates the existence of adherent and non-adherent monocytes, both capable of differentiation in vitro. In 14 patients with advanced Hodgkin's disease (HD) and 14 normal controls, monocyte differentiation was studied applying both culture modalities. The enzyme levels, reflecting growth and intermediary metabolism, were similar for both groups. The adherent capacity and yield, both in teflon and in plastic, after 15 days was comparable for both groups. It was concluded that in vitro monocyte differentiation in the presence of autologous serum was qualitatively and quantitatively normal in advanced HD; this is in favour of an intrinsically normal function of monocytes in HD.     

Mental fatigue and task control: planning and preparation

The effects of mental fatigue on planning and preparation for future actions were examined, using a task switching paradigm. Fatigue was induced by "time on task," with subjects performing a switch task continuously for 2 hr. Subjects had to alternate between tasks on every second trial, so that a new task set was required on every second trial. Manipulations of response-stimulus intervals (RSIs) were used to examine whether subjects prepared themselves for the task change. Behavioral measurements, event-related potentials (ERPs), and mood questionnaires were used to assess the effects of mental fatigue. Reaction times (RTs) were faster on trials in which no change in task set was required in comparison with switch trials, requiring a new task set. Long RSIs were used efficiently to prepare for the processing of subsequent stimuli. With increasing mental fatigue, preparation processes seemed to become less adequate and the number of errors increased. A clear poststimulus parietal negativity was observed on repetition trials, which reduced with time on task. This attention-related component was less pronounced in switch trials; instead, ERPs elicited in switch trials showed a clear frontal negativity. This negativity was also diminished by time on task. ERP differences between repetition and switch trials became smaller with increasing time on task.     

GATA6 mutations: Characterization of two novel patients and a comprehensive overview of the GATA6 genotypic and phenotypic spectrum

The first human mutations in GATA6 were described in a cohort of patients with persistent truncus arteriosus, and the phenotypic spectrum has expanded since then. This study underscores the broad phenotypic spectrum by presenting two patients with de novo GATA6 mutations, both exhibiting complex cardiac defects, pancreatic, and other abnormalities. Furthermore, we provided a detailed overview of all published human genetic variation in/near GATA6 published to date and the associated phenotypes (n = 78). We conclude that the most common phenotypes associated with a mutation in GATA6 were structural cardiac and pancreatic abnormalities, with a penetrance of 87 and 60%, respectively. Other common malformations were gallbladder agenesis, congenital diaphragmatic hernia, and neurocognitive abnormalities, mostly developmental delay. Fifty‐eight percent of the mutations were de novo, and these patients more often had an anomaly of intracardiac connections, an anomaly of the great arteries, and hypothyroidism, compared with those with inherited mutations. Functional studies mostly support loss‐of‐function as the pathophysiological mechanism. In conclusion, GATA6 mutations give a wide range of phenotypic defects, most frequently malformations of the heart and pancreas. This highlights the importance of detailed clinical evaluation of identified carriers to evaluate their full phenotypic spectrum.     

Reversed diurnal variation in depression: associations with a differential antidepressant response, tryptophan: large neutral amino acid ratio and serotonin transporter polymorphisms

BACKGROUND: Although diurnal variation of mood is a widely recognized symptom of depression, the clinical, neurobiological and psychopharmacological significance of this symptom has not previously been reported. METHOD: A total of 195 depressed out-patients underwent a detailed clinical and neurobiological assessment, and were then randomized to treatment with either fluoxetine or nortriptyline. RESULTS: Of the 195 depressed patients, 62 had a pattern of reversed diurnal variation (i.e. worse in the evening). Those with reversed diurnal variation had a poorer response to a serotonergic anti-depressant, were less likely to have bipolar II disorder, had a higher tryptophan: large neutral amino acid ratio and had different allele frequencies of the polymorphisms in the promoter region of the serotonin transporter. CONCLUSIONS: These findings raise the possibility of serotonergic influence on diurnal variation, and that the symptom of reversed diurnal variation is of relevance to antidepressant prescribing.     

Interleukin-2 activated NK cells do not use the CD95L- and TRAIL-pathways in the rapid induction of apoptosis of rat colon carcinoma CC531s cells

Natural Killer (NK) cells can induce apoptosis in target cells in at least four ways: by secretion of granzyme B/perforin (GrB/P) and via the CD95L, TRAIL and TNF-α pathways. In this study we examined the pathways used by interleukin-2 activated rat NK (A-NK) cells to induce apoptosis in the rat colon carcinoma cell line CC531s. Co-incubation of A-NK cells with CC531s cells for three hours resulted in 70% apoptosis in the latter. Addition of the GrB/P pathway-inhibitor concanamycin A reduced the number of apoptotic cells to 54%. Blockade of the CD95L, TRAIL and TNF-α pathways by specific antibodies hardly had an additional effect. However, co-incubation with transfected MEC cells that expressed CD95L or 2PK3-cells that expressed TRAIL did induce apoptosis in CC531s cells. Furthermore the A-NK cells contained CD95L and TRAIL. However, comparison of non- and permeabilized cells revealed that the majority of TRAIL was present in the cytosol of A-NK cells and was not available for induction of apoptosis. The presence of elevated levels of bcl-2 in CC531 cells reduced the sensitivity towards induction of apoptosis both by A-NK cells as well as the CD95L and TRAIL expressing cell lines. Using the caspase-inhibitors ac-IEPD-CHO, ac-DEVD-CHO and zVAD-fmk, it was shown that inhibition of the effector caspase-3 prevented A-NK cell induced apoptosis in CC531-bcl-2 cells, but not in CC531s cells. In conclusion, A-NK cells kill by secretion of GrB/P and not by the CD95L, TRAIL or TNF pathways albeit both CD95L and TRAIL are produced by the A-NK cells.