HETEROCHROMATIN AND KARYOTYPE REORGANIZATION IN FISH OF THE FAMILY ANOSTOMIDAE (CHARACIFORMES)

Mitotic chromosomes of four fish species of the family Anostomidae, belonging to the genera Leporinus, Leporellus, and Schizodon, were studied. With 2n = 54 meta- and submetacentric chromosomes, this family appears to be characterized by marked karyotypic stability. Although perceptible differences exist, mainly in the amount of constitutive heterochromatin present in the chromosomes of these species, these differences do not affect the structure and/or size of these chromosomes. Chromatin substitutions and/or modifications may have led, in one direction, to an increase in heterochromatin in some species and, in the opposite direction, to heterochromatin reduction in others. Whether these changes are accompanied by changes in the amount of euchromatin in the chromosomes is an open question. The nucleolar organizer regions, which may be located on different chromosomes in the various species, may also be indicators of reorganization of these karyotypes.

Characterization of ZnO-degraded varistors used in high-tension devices

The effects of the degradation process on the structural, microstructural and electrical properties of ZnO-based varistors were analyzed. Rietveld refinement showed that the BiO2-x phase is affected by the degradation process. Besides the changes in the spinel phase, the degradation process also affects the lattice microstrain in the ZnO phase. Scanning electron microscopy analysis showed electrode-melting failure, while wavelength dispersive X-ray spectroscopy qualitative analysis showed deficiency of oxygen species at the grain boundaries in the degraded samples. Atomic force microscopy using electrostatic mode force illustrated a decrease in the charge density at the grain boundaries of the degraded sample. Transmission electron microscopy showed submicrometric spinel grains embedded in a ZnO matrix, but their average grain size is smaller in the degraded sample than in the standard one. Long pulses appeared to be more harmful for the varistors' properties than short ones, causing higher leakage current values. The electrical characteristics of the degraded sample are partially restored after heat treatment in an oxygen-rich atmosphere. (C) 2006 Elsevier Ltd. All rights reserved.

Macro- and microstructure of the superior cervical ganglion in dogs, cats and horses during maturation

The superior cervical ganglion (SCG) provides sympathetic input to the head and neck, its relation with mandible, submandibular glands, eyes (second and third order control) and pineal gland being demonstrated in laboratory animals. In addition, the SCG's role in some neuropathies can be clearly seen in Horner's syndrome. In spite of several studies published involving rats and mice, there is little morphological descriptive and comparative data of SCG from large mammals. Thus, we investigated the SCG's macro- and microstructural organization in medium (dogs and cats) and large animals (horses) during a very specific period of the post-natal development, namely maturation (from young to adults). The SCG of dogs, cats and horses were spindle shaped and located deeply into the bifurcation of the common carotid artery, close to the distal vagus ganglion and more related to the internal carotid artery in dogs and horses, and to the occipital artery in cats. As to macromorphometrical data, that is ganglion length, there was a 23.6% increase from young to adult dogs, a 1.8% increase from young to adult cats and finally a 34% increase from young to adult horses. Histologically, the SCG's microstructure was quite similar between young and adult animals and among the 3 species. The SCG was divided into distinct compartments (ganglion units) by capsular septa of connective tissue. Inside each ganglion unit the most prominent cellular elements were ganglion neurons, glial cells and small intensely fluorescent cells, comprising the ganglion's morphological triad. Given this morphological arrangement, that is a summation of all ganglion units, SCG from dogs, cats and horses are better characterized as a ganglion complex rather than following the classical ganglion concept. During maturation (from young to adults) there was a 32.7% increase in the SCG's connective capsule in dogs, a 25.8% increase in cats and a 33.2% increase in horses. There was an age-related increase in the neuronal profile size in the SCG from young to adult animals, that is a 1.6-fold, 1.9-fold and 1.6-fold increase in dogs, cats and horses, respectively. on the other hand, there was an age-related decrease in the nuclear profile size of SCG neurons from young to adult animals (0.9-fold, 0.7-fold and 0.8-fold in dogs, cats and horses, respectively). Ganglion connective capsule is composed of 2 or 3 layers of collagen fibres in juxtaposition and, as observed in light microscopy and independently of the animal's age, ganglion neurons were organised in ganglionic units containing the same morphological triad seen in light microscopy. Copyright (c) 2007 S. Karger AG, Basel.

In vitro evaluation of acidified toothpastes with low fluoride content

Fluoride toothpastes are a risk factor for the development of dental fluorosis. Products with low fluoride content offer a higher security, but their effectiveness must be proven. The aim of this in vitro study was to compare two acidified toothpastes with low fluoride concentration (412 and 550 mu g F/g) with neutral toothpastes. Bovine enamel blocks were selected by surface microhardness (SMH) and randomized to twelve groups of 13, according to the fluoride concentration in toothpaste (placebo, 275, 412, 550 or 1,100 jig F/g) and pH (7.0 or 5.5). Two commercially available toothpastes were also studied: a 1,100-mu g F/g, pH 7.0 paste (positive control) and a children's paste (500 mu g F/g, pH 7.0). The blocks were subjected to pH cycling for 7 days. The toothpaste treatment was done twice daily. Surface and cross-sectional microhardnesses were assessed to calculate the percentage change of SMH (%SMH) and the mineral loss (Delta Z). The amount of fluoride, calcium and phosphorus in the solutions after the pH cycling was also analyzed. Compared to neutral toothpastes, the acidified toothpastes reduced the %SMH in all F concentrations. Higher F and lower Ca and P concentrations were found in solutions for the acidified toothpastes. Regarding AZ, only the positive control, 1,100-mu g F/g (acidified and neutral) groups were not statistically different. The acidified toothpastes showed a dose-response relationship with all variables. For the low-fluoride toothpastes evaluated, only the 550-mu g F/g acidified paste had the same anticariogenic action as the 1,100-mu g F/g neutral paste.

PHARMACOLOGICAL EVALUATION OF THE INHIBITORY EFFECT OF EXTRACTS FROM ANCHIETIA-SALUTARIS ON THE HISTAMINE-RELEASE INDUCED IN THE RAT AND THE GUINEA-PIG

The tea made with leaves and stems of plant Anchietia salutaris is traditionally used in Brazil to treat allergies. We examined the effects of a crude aqueous extract and of purified fractions of this plant on the histamine release induced in rat and guinea pig tissues. The crude extract (3-10 mu g/ml) inhibits the histamine release induced by compound 48/80 (0.5 mu g/ml) and antigen in rat peritoneal mast cells. The inhibition is significant after 10 s of preincubation and is completed after 3 min. The crude extract dissolved in the perfusion fluid (1-30 mu g/ml) also inhibits the histamine release induced in guinea pig heart by cardiac anaphylaxis and in hearts from pretreated animals (10-100 mg/kg i.p.). In pretreated animals, the effect manifests after 3 h, is maximum after 12 h and disappears after 48 h. The histamine release induced in isolated guinea pig heart by ionophore A23187 is inhibited by similar doses as in antigen-induced histamine release. Extraction with solvents concentrated the active principle (s) in the hexane fractions, as demonstrated by the inhibition of the histamine release induced by antigen in isolated cells from guinea pig heart dispersed with collagenase. In subfractions produced by the fractionation of the hexane fraction, the active principle(s) concentrated in the subfractions obtained by extraction with hexane and ethyl acetate, which shows the low polarity of the compound(s). The same subfractions that inhibit the histamine release induced by antigen in cells from guinea pig heart also inhibit pulmonary cells. Our result show that A. salutaris contains low-polarity compound(s) that inhibit the histamine release induced by three different mechanisms in mast cells from two animal species. These facts suggest that the active principle(s) of A, salutaris could be useful in the treatment of allergies and/or as a tool for the study of mast cell secretions.

Effect of rinsing with water immediately after APF gel application on enamel demineralization in situ

This double-blind crossover in situ study evaluated the effect of rinsing with water immediately after the application of acidulated phosphate fluoride (APF) on enamel demineralization. APF application was followed by: no rinsing or consuming of liquids or solids for the next 30 min; immediately washing with water jet or drinking of a glass of water. All treatments showed a statistically significant decrease in enamel mineral loss compared to the control (p < 0.05), but the differences among treatments were not significant (p > 0.05). The data suggest that the recommendation of asking patients to refrain from drinking water following professional APF application does not seem to have an influence on the anticaries effect of fluoride. Copyright (C) 2005 S. Karger AG, Basel.

Influence of growth rate and length on fluoride detection in human nails

This study aimed to determine the lag time between increased fluoride (F) intake and F detection in human nails, as well as the influence of nails growth rate and length on this. Ten 20- to 35-year-old volunteers received 1.8 mg F daily, for 30 days. Nail growth rate and length were determined for all fingernails and toenails. Nail samples were collected at the beginning of the study and every 2 weeks (15 collections in all) and F concentrations were determined. The growth rate was statistically higher in fingernails than in toenails. No statistically significant differences were observed between right and left sides. Growth rate was significantly greater for big toenails than for the other toenails, but this pattern was not found for fingernails. The estimated mean lag times for F detection in fingernails and toenails were 101 and 123 days, respectively. An apparent increase in fingernail F concentrations was observed 84 days after the beginning of the study, although this was not statistically different from baseline. For toenails, statistically significant increases in F concentration in relation to baseline were observed 112 and 140 days after increased F ingestion. These increases occurred within the 95% confidence intervals for the calculated mean lag time for fluoride detection in nails. Considering the large amount of sample provided by the big toenails, together with their faster growth rate, as well as the fact that toenails are less prone to environmental contamination, our data suggest that big toenails are more suitable biomarkers of fluoride intake.

PRESYNAPTIC AND POSTSYNAPTIC MECHANISMS INVOLVED IN TETANIC FADE INDUCED BY PANCURONIUM IN THE ISOLATED RAT MUSCLE

The mechanisms underlying the fade of the tetanic contraction induced by pancuronium were studied in vitro by means of myographical and electrophysiological techniques in the extensor digitorum longus muscle of the rat. Pancuronium (0.5 mu mol/l) induced a complete fade of the tetanic contraction while leaving the twitch unaffected. At the same concentration it decreased the amplitude and increased the tetanic rundown of trains of endplate potentials (e.p.ps) evoked in the frequency of 50 Hz. The electrophysiological changes induced by pancuronium were due to decreases in both quantal sizes and quantal contents of the e.p.ps. The former effect was the result of a postsynaptic competitive action and the latter of a presynaptic inhibitory action of that compound. The decrease in quantal. content affected the e.p.ps starting from the first in the train and became larger during the generation of the sequence of e.p.ps. This intensified their tetanic rundown. It is concluded that the fade of the tetanic contraction induced by pancuronium is due to a summation of pre- and postsynaptic actions and, therefore, not only to an increase in the tetanic rundown of e.p.ps. Possible explanations for the distinct abilities of neuromuscular blockers in affecting tetani and twitches in a differential manner are also discussed.

Estimation of growth fraction in fine needle aspirates from non-Hodgkin's lymphoma using anti-proliferating cell nuclear antigen - Correlation with the Kiel classification

OBJECTIVE: This study was undertaken to assess whether fine needle aspirates from non-Hodgkins lymphoma (NHL) could be used for growth fraction analysis with proliferating cell nuclear antigen (PCNA) staining and if there was a relationship between the growth fraction and cytomorphologic classification according to the Kiel classification.STUDY DESIGN: the study group consisted of 40 patients with NHL diagnosed by fine needle aspiration (FNA) cytology. The cytologic classification of the lymphomas was made by two cytopathologists on May-Grunwald-Giemsa-stained slides using the Kiel classification. There were 27 cases of low and 13 of high grade lymphoma. The estimation of the growth fraction was made by PCNA immunoreactivity. The PCNA index was quantitated in smears by counting an average of 1,000 cells, and the count teas correlated with the cytomorphologic classification.RESULTS: There was It strong correlation between the PCNA index and lymphoma grading. High grade lymphomas exhibited a mean PCNA positivity of 74.0%, which was significantly higher (P <.001) than that of low grade lymphomas (17.6%).CONCLUSION: Our study showed that PCNA evalua tion is suitable for smears obtained by FNA on NHL, correlates with increasing grades of lymphoma according to the Kiel classification and may offer a method of monitoring treatment of lymphoma.

Clarifications on breakpoints in HSAX and BTAX by comparative mapping of F9, HPRT, and XIST in cattle

The coagulation factor IX gene (179), the hypoxanthine phosphoribosyl transferase 1 gene (HPRT1), and the X-inactive specific transcript gene (XIST) were physically assigned in cattle to analyze chromosomal breakpoints on BTAX recently identified by radiation hybrid (RH) mapping experiments. Whereas the FISH assignment of XIST indicates a similar location on the q-arm of the human and cattle X chromosomes, the locus of HPRT1 supported the assumption of a chromosome rearrangement between the distal half of the q-arm of HSAX and the p-arm of BTAX identified by RH mapping. F9 previously located on the Cl-arm of BTAX was assigned to the p-arm of BTAX using RH mapping and FISH. The suggested new position of F9 close to HPRT I supports the homology between HSAXq and BTAXp. The F9 locus corresponds with the gene order found in the homologous human chromosome segment. XIST was assigned on BTAXq23, HPRT1 and F9 were mapped to BTAXp22, and the verification of the location of F9 in a 5000 rad cattle-hamster whole genome radiation hybrid panel linked the gene to markers URB10 and HPRT1. Copyright (C) 2003 S. Karger AG, Basel.