The effects of hypergravity on vestibular epithelia and behaviour of the rat

Researchers examined the vestibules of rats and hamsters raised in a centrifuge to determine the histology of the peripheral sensory system, vestibule-induced ocular reflexes, and vestibular-controlled behavior. Actin and tubulin structures were compared in animals raised in hypergravity and normal gravity. Air righting and swimming also were compared.     

Functional morphology of suprachiasmatic nuclei neurons of rat hypothalamus after the combined influence of x-irradiation and light exposure

For estimation of light radiomodification and cellular neuroadaptation of the circadian pacemarker, the morphological changes of suprachiasmatic nuclei (SCN) neurons of rat hypothalamus after 48-hours bright light exposure, the single 5 Gy whole-body X-irradiation and their combination were subjected to analysis. The dynamics of reactive and reparative changes has got a phasic character. Temporary desynchronous changes were developed in the course of the early period. Age morphological changes after X-ray and combined irradiation were discovered in the remote period. The plastic diapason of ventrolateral division (SCNv) is more considerable in comparison with dorsomedial division (SCNd). The synergism of X-irradiation and light exposure was discovered in SCNd.     

The influence of maternal nicotine exposure on the interalveolar septal status of neonatal rat lung.

The aim of this study was to determine the effect of maternal nicotine exposure (1 mg nicotine/kg body mass/day, subcutaneously) on the status of the alveolar septa of the 1 to 21 day old offspring. The data obtained showed swelling of type II and interstitial cell mitochondria. The type I:type II cell ratio decreased as a result of type II cell proliferation. The number of capillaries per unit length of septum was also significantly lower than that of control lung. Ruptured blood-air barriers also occur in the nicotine exposed lungs of rats of all age groups. The results show that maternal nicotine exposure interfered with the morphometric and morphologic characteristics of the septa of lung tissue of the offspring.     

The influence of fixation on the morphology of mitotic chromosomes

It is well known that there is a strong influence of fixation, i.e., acetic methanol versus formaldehyde, on the chromosome morphology at stages of the first meiotic division. In this study the influence of both these types of fixation on the morphology of mitotic chromosomes was examined in human lymphocytes. After methanol-acetic acid (3:1) fixation, the chromosomes show the "classical" condensed shape in which it is not always possible to recognize the two sister chromatids. These chromosomes are accessible to the conventional G-, R-, and C-banding techniques. After formaldehyde fixation at a relatively high pH, the chromosomes are thinner and longer (two to six times) when compared with chromosomes following methanol-acetic acid fixation. They show a scaffold-like morphology, sometimes with a halo of thin material around it. In all cases the two sister chromatids could be recognized. This chromosome structure could be easily stained with silver, Giemsa, 4,6-diamino-2-phenyl-indole (DAPI), and fluorescein isocyanate isomere 1 (FITC). The results obtained following these stainings gave no indication to any specific chemical composition of a probable central scaffold. The scaffold-like structures were not accessible to G-, R-, or C-banding techniques. The only effect observed following these banding techniques was the disappearance of the halo of thin material around the central scaffold-like structure.     

The effect of wave exposure on the morphology of Ecklonia radiata

This study examined the consistency of the effect of wave exposure on the morphology of Ecklonia radiata, a small kelp, across a broad geographic range (>1100 km). Fifteen morphological characters were measured on individuals from sites of low (2.5 ± 0.8 S.E.) and high (12.2 ± 2.0 S.E.) wave exposure (Baardseth's index) within six locations in southwestern Australia. With the exception of lateral width (P = 0.0001), none of the morphological characters were consistently statistically different (P > 0.06) between high and low wave exposure and correlations with wave exposure were generally weak (r < 0.60). While 12 of the 15 characters were statistically different (P < 0.008) between sites of different exposure within at least one location, the direction of difference (significant or not) was opposite between some locations for all but one character (lateral width). ANOSIM was not able to separate thalli from high and low exposure when all locations were pooled (Clarke's R = 0.127), but within each location most sites showed better separation (0.126 < Clarke's R < 0.829). Despite the lack of statistical differences, trends suggested that E. radiata responds to exposure by having drag-reducing (small size, narrow laterals and blades, low spinosity) and strength-increasing (relatively large holdfast, thick stipe and thick blades and lamina) morphological traits, as observed for several other kelps in small-scale studies. We conclude that while wave exposure does have an effect on kelp morphology, the effect is not independent of other location-specific processes.     

The influence of differing connective tissue substrates on the maintenance of adult stratified squamous epithelia

Summary The interaction between adult stratified squamous epithelium and its supporting connective tissue possibly involves both permissive and directive influences. To examine the effect of vitality and specificity of connective tissue on the maintenance of epithelial structure and histo-differentiation, specimens of skin and oral mucosa from various regions of adult mice were separated using either EDTA or trypsin. Prior to transplantation, the epithelium was recombined with either inverted homologous connective tissue or with connective tissue that had been killed either by heating or repeated freeze-thawing. Epithelial sheets were also transplanted onto the graft bed alone or in combination with striated muscle or tendon.Normal patterns of cytodifferentiation were maintained when the epithelium was recombined with inverted or frozen-thawed subepithelial connective tissue but there was a loss of spatial organization on the frozen-thawed connective tissue. In contrast, heat-killed or trypsin-treated frozen-thawed subepithelial connective tissue and non-dermal connective tissue failed to maintain a viable epithelium. These observations suggest that subepithelial connective tissues (dermis, lamina propria) but not deep connective tissues facilitate epithelial proliferation and histodifferentiation.Supported by NIH/NIDR RO1 DEO5190     

铅对小鼠精子形态影响的观察

通过精子畸形试验,观察了醋酸铅对小鼠雄性生殖细胞的影响。结果表明,随着醋酸铅浓度的增大,精子畸形率增加,提示了铅对哺乳动物的雄性生殖细胞具有潜在的诱变能力。     

Morphological effects of the catechol estrogens on rat epididymal epithelia

The 2-hydroxy and 4-hydroxyestradiols (2-/4-OHE₂) caused marked cytotoxic effects, including vacuolation and nuclear changes, in rat epididymal epithelia, after exposure to very low levels (40 ng/rat/week) for 20 weeks. The effects of the 2-/4-OHE₂ metabolites were more pronounced than that of estradiol-17β(E₂).     

Direct effects of airborne PM2.5 exposure on macrophage polarizations

BackgroundExposure of atmospheric particulate matter with an aerodynamic diameter less than 2.5 μm (PM_2.5) is epidemiologically associated with illnesses. Potential effects of air pollutants on innate immunity have raised concerns. As the first defense line, macrophages are able to induce inflammatory response. However, whether PM_2.5 exposure affects macrophage polarizations remains unclear.MethodsWe used freshly isolated macrophages as a model system to demonstrate effects of PM_2.5 on macrophage polarizations. The expressions of cytokines and key molecular markers were detected by real-time PCR, and flow cytometry. The specific inhibitors and gene deletion technologies were used to address the molecular mechanisms.ResultsPM_2.5 increased the expression of pro-inflammatory cytokines granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-6 (IL-6), interleukin-1β (IL-1β), tumor necrosis factor alpha (TNFα). PM_2.5 also enhanced the lipopolysaccharide (LPS)-induced M1 polarization even though there was no evidence in the change of cell viability. However, PM_2.5 significantly decreased the number of mitochondria in a dose dependent manner. Pre-treatment with NAC, a scavenger of reactive oxygen species (ROS), prevented the increase of ROS and rescued the PM_2.5-impacted M1 but not M2 response. However, mTOR deletion partially rescued the effects of PM_2.5 to reduce M2 polarization.ConclusionsPM_2.5 exposure significantly enhanced inflammatory M1 polarization through ROS pathway, whereas PM_2.5 exposure inhibited anti-inflammatory M2 polarization through mTOR-dependent pathway.General significanceThe present studies suggested that short-term exposure of PM_2.5 acts on the balance of inflammatory M1 and anti-inflammatory M2 macrophage polarizations, which may be involved in air pollution-induced immune disorders and diseases. This article is part of a Special Issue entitled Air Pollution, edited by Wenjun Ding, Andrew J. Ghio and Weidong Wu.     

The influence of culture conditions on cell morphology and tyrosine aminotransferase levels in rat liver epithelial cell lines

Experimental conditions known to alter the shape, permeability and organization of cells were used to find out their effects on tyrosine aminotransferase (TAT) in rat liver epithelial cell lines. To produce a more spheroidal morphology for non-malignant cells than that obtainable on plastic, floating collagen and poly(2-hydroxyethylmethacrylate) (poly(HEMA)), were used as substrata. Under these experimental conditions the basal level of TAT activity increased 1.5–2.5-fold. When monolayer cultures were permeabilized by the use of a hypertonic salt solution, the basal activity increased 4–5-fold. TAT activity was also elevated in hepatoma cells cultured in anchorage-independent conditions. The enzyme was not inducible by dexamethasone (DEX) under any of these culture conditions, and the lack of induction was not due to the absence of receptors for this hormone. These studies have shown that the production of TAT, one of the characteristics of adult liver, has persisted in a number of rat epithelial cell lines derived from normal, malignant or regenerating liver and its activity was influenced by the different culture conditions employed.     

The influence of hypoxic cell-free perfusion and ischemia on cell morphology in the proximal tubular S2-segment of the rat kidney

In the present study, in-situ perfused rat kidneys were used as a model to demonstrate the different morphological changes induced by various periods of warm ischemia or of warm hypoxic cell-free perfusion. Light and electron microscopic evaluation revealed no changes in the S2 proximal tubular cells after short exposure times of up to 4 min, whereas longer periods resulted in changes ranging from slight alterations (at 10 min) to severe damage (at 60 min). Warm hypoxic cell-free perfusion induced obvious alterations in the proximal tubular cells somewhat sooner than warm ischemia. The microscopical findings were consistent with the statistics of a detailed morphometrical analysis performed on the mitochondrial diameter. The results were further substantiated by counting intramitochondrial electron-dense condensations ('flocculent densities') as indicators of irreversible cell alteration.     

Somatosensory influence on postural response to galvanic vestibular stimulation

We investigated how postural responses to galvanic vestibular stimulation were affected by standing on a translating support surface and by somatosensory loss due to diabetic neuropathy. We tested the hypothesis that an unstable surface and somatosensory loss can result in an increase of vestibulospinal sensitivity. Bipolar galvanic vestibular stimulation was applied to subjects who were standing on a force platform, either on a hard, stationary surface or during a backward platform translation (9 cm, 4.2 cm/s). The intensity of the galvanic stimulus was varied from 0.25 to 1 mA. The amplitude of the peak body CoP displacement in response to the galvanic stimulus was plotted as a function of stimulus intensity for each individual. A larger increase in CoP displacement to a given increase in galvanic current was interpreted as an increase of vestibulospinal sensitivity. Subjects with somatosensory loss in the feet due to diabetes showed higher vestibulospinal sensitivity than healthy subjects when tested on a stationary support surface. Control subjects and patients with somatosensory loss standing on translating surface also showed increased galvanic response gains compared to stance on a stationary surface. The severity of the somatosensory loss in the feet correlated with the increased postural sensitivity to galvanic vestibular stimulation. These results showed that postural responses to galvanic vestibular stimulus were modified by somatosensory information from the surface. Somatosensory loss due to diabetic neuropathy and alteration of somatosensory input during stance on translating support surface resulted in increased vestibulospinal sensitivity.