Ablastin: Control of Trypanosoma musculi infections in mice

Trypanosoma musculi infections in CBA mice consist of a phase of increasing parasitemia during which dividing forms of the parasite are present in the blood, followed by a period when only nondividing trypomastigotes are seen. A second crisis terminates the blood infection and leaves the host immune, but small numbers of trypanosomes, including multiplicative forms, persist in the kidneys for many months. Studies were made involving infections in T-lymphocyte deprived mice, the effects of passive transfer of serum and cells, measurement of DNA synthesis by the parasite, serological responses, and in vitro effects of serum on the trypanosomes. These indicated that the initial check on the increase in blood parasitemia is due in part to two humoral factors. One of these has a trypanocidal effect (this is thought to be an IgM antibody) while the other, which may be an IgG antibody, is the ablastin that inhibits further reproduction by the parasite. Both trypanocidal and ablastic effects were demonstrable in the serum of immune mice yet the parasite was still able to survive and multiply in the kidneys.     

Renal physiology of two southern African Mastomys species (Rodentia: Muridae): a salt-loading experiment to assess concentrating ability

Aspects of renal physiology were examined to test the hypothesis that two cryptic species of the genus Mastomys (Mastomys natalensis and Mastomys coucha) are geographically separated by differences in aridity tolerance. Laboratory-bred females of each species were subjected to different levels of salinity in their water source (distilled water, 0.9% NaCl, and 1.5% NaCl; 10 conspecifics in each group) from weaning until sexual maturity. Individuals of the two species exhibited similar rates of water consumption and urine production. The salinity treatments caused sodium diuresis in both species, evident in increased urine volume, decreased osmolality and increased osmotic output. Urine concentration, kidney mass and kidney relative medullary area (RMA) did not differ between species. The results of our study do not support the hypothesis that differences in osmoregulatory ability separate these two cryptic species. Nor do they support the use of salt loading to elicit maximum urine concentrations in mammals.     

Reduced plasma angiotensin II levels are reversed by hydroxyurea treatment in mice with sickle cell disease

Aims

Sickle cell disease (SCD) pathogenesis leads to recurrent vaso-occlusive and hemolytic processes, causing numerous clinical complications including renal damage. As vasoconstrictive mechanisms may be enhanced in SCD, due to endothelial dysfunction and vasoactive protein production, we aimed to determine whether the expression of proteins of the renin–angiotensin system (RAS) may be altered in an animal model of SCD.

Main methods

Plasma angiotensin II (Ang II) was measured in C57BL/6 (WT) mice and mice with SCD by ELISA, while quantitative PCR was used to compare the expressions of the genes encoding the angiotensin-II-receptors 1 and 2 (AT1R and AT2R) and the angiotensin-converting enzymes (ACE1 and ACE2) in the kidneys, hearts, livers and brains of mice. The effects of hydroxyurea (HU; 50–75 mg/kg/day, 4 weeks) treatment on these parameters were also determined.

Key findings

Plasma Ang II was significantly diminished in SCD mice, compared with WT mice, in association with decreased AT1R and ACE1 expressions in SCD mice kidneys. Treatment of SCD mice with HU reduced leukocyte and platelet counts and increased plasma Ang II to levels similar to those of WT mice. HU also increased AT1R and ACE2 gene expression in the kidney and heart.

Significance

Results indicate an imbalanced RAS in an SCD mouse model; HU therapy may be able to restore some RAS parameters in these mice. Further investigations regarding Ang II production and the RAS in human SCD may be warranted, as such changes may reflect or contribute to renal damage and alterations in blood pressure.     

Schistosoma japonicum: Immunopathology of nephritis in Macaca fascicularis

Macaca monkeys experimentally infected with Schistosoma japonicum developed a chronic progressive kidney lesion characterized by an increase of mesangial matrix, local glomerular hypercellularity, and local thickening of glomerular basement membrane. Immunofluorescence studies revealed the localization of IgG, IgM, IgA, and IgE immunoglobulins mostly in the mesangial area of the glomeruli accompanied by the deposition of Schistosoma antigens. By electron microscopy, in addition to the local thickening of the glomerular basement membrane, dense homogeneous deposits and those with moth-eaten appearance were detected in the mesangial matrix. These findings suggest that worms in the bloodstream continuously release antigenic materials that stimulate host's antibody response belonging to various immunoglobulin classes including IgE. The produced antibodies and antigens would form immune complexes that deposited in the glomeruli. The increased vascular permeability caused by antigen-IgE antibody interaction may play an important role in the deposition of immune complexes and in the rapid development of kidney injury.     

Attenuation of cellular antioxidant defense mechanisms in kidney of rats intoxicated with carbofuran

Carbofuran, an anticholinestrase carbamate, is commonly used as an insecticide. Its toxic effect on kidney is less established. The present study was designed to investigate the effect of carbofuran on kidneys and to understand the mechanism involved in its nephrotoxicity. Male Wistar rats were divided into two groups of eight animals each; control animals received sunflower oil (vehicle) and carbofuran exposed animals were treated with carbofuran (1 mg/kg body weight) orally for 28 days. At the end of the treatment, significant increase was observed in urea and creatinine levels in serum along with the inhibition of acetylcholinesterase, suggesting nephrotoxicity. The antioxidant defense system of animals treated with carbofuran was altered in terms of increased lipid peroxidation, reduced glutathione, and total thiols and decreased activity of antioxidant enzymes (superoxide dismutase and catalase). The results indicate that carbofuran is nephrotoxic and increased oxidative stress appears to be involved in its nephrotoxic effects. © 2012 Wiley Periodicals, Inc. J Biochem Mol Toxicol 26:393–398, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/jbt.21433     

Effect of circadian on the activities of ion transport ATPases and histological structure of kidneys in mice

The impacts of unnatural every day cycles (circadian) for 60 days on the histological structure of kidneys and ATPase activities in MF1 mice were studied. The exposure times were 16 h dark, 16 h light, 24 h dark, and 24 h light, and control exposure times were 12 h dark followed by 12 h light. Our results showed an increase in the total ATPase activity of mice in all groups. Additionally, the activity of the enzyme Na⁺/K⁺-ATPase was increased after 24 h darkness, 24 h light, and 16 h light exposures compared to control. The enzyme Mg⁺²-ATPase activities of the groups were higher when exposed to 16 h light, 24 h light, 24 h darkness and 16 h darkness. The activities of total ATPase, Na⁺/K⁺-ATPase and Mg⁺²-ATPase in kidneys were increased in all groups after 24 h light, 24 h darkness, 16 h darkness and 16 h light exposures. Interestingly, the activity of V-type ATPase was reduced after 16 h darkness, 24 h darkness and 16 h light. Taking everything into account, changes in the day by day cycle prompt neurotic changes, enzymatic and histological changes in the kidneys of mice. More studies should be directed to explore the impacts of light and darkness that can prompt these progressions.     

Proliferating cell nuclear antigen (PCNA) as a proliferative marker during embryonic and adult zebrafish hematopoiesis

We investigated the expression of proliferative cell nuclear antigen (PCNA) in zebrafish to delineate the proliferative hematopoietic component during adult and embryonic hematopoiesis. Immunostaining for PCNA and enhanced green fluorescence protein (eGFP) was performed in wild-type and fli1-eGFP (endothelial marker) and gata1-eGFP (erythroid cell marker) transgenic fish. Expression of PCNA mRNA was examined in wild-type and chordin morphant embryos. In adult zebrafish kidney, the renal tubules are surrounded by endothelial cells and it is separated into hematopoietic and excretory compartments. PCNA was expressed in hematopoietic progenitor cells but not in mature neutrophils, eosinophils or erythroid cells. Some PCNA+ cells are scattered in the hematopoietic compartment of the kidney while others are closely associated with renal tubular cells. PCNA was also expressed in spermatogonial stem cells and intestine crypts, consistent with its role in cell proliferation and DNA synthesis. In embryos, PCNA is expressed in the brain, spinal cord and intermediate cell mass (ICM) at 24 h-post fertilization. In chordin morphants, PCNA is significantly upregulated in the expanded ICM. Therefore, PCNA can be used to mark cell proliferation in zebrafish hematopoietic tissues and to identify a population of progenitor cells whose significance would have to be further investigated.     

Cardiac,skeletal muscle and serum irisin responses to with or without water exercise in young and old male rats: Cardiac muscle produces more irisin than skeletal muscle

Irisin converts white adipose tissue (WAT) into brown adipose tissue (BAT), as regulated by energy expenditure. The relationship between irisin concentrations after exercise in rats compared humans after exercise remains controversial. We therefore: (1) measured irisin expression in cardiac and skeletal muscle, liver, kidney, peripheral nerve sheath and skin tissues, as also serum irisin level in 10 week-old rats without exercise, and (2) measured tissue supernatant irisin levels in cardiac and skeletal muscle, and in response to exercise in young and old rats to establishing which tissues produced most irisin. Young (12 months) and old rats (24 months) with or without 10 min exercise (water floating) and healthy 10 week-old Sprague-Dawley rats without exercise were used. Irisin was absent from sections of skeletal muscle of unexercised rats, the only part being stained being the perimysium. In contrast, cardiac muscle tissue, peripheral myelin sheath, liver, kidneys, and skin dermis and hypodermis were strongly immunoreactivity. No irisin was seen in skeletal muscle of unexercised young and old rats, but a slight amount was detected after exercise. Strong immunoreactivity occurred in cardiac muscle of young and old rats with or without exercise, notably in pericardial connective tissue. Serum irisin increased after exercise, being higher in younger than older rats. Irisin in tissue supernatants (cardiac and skeletal muscle) was high with or without exercise. High supernatant irisin could come from connective tissues around skeletal muscle, especially nerve sheaths located within it. Skeletal muscle is probably not a main irisin source.     

Water use and the thermoregulatory behaviour of kangaroos in arid regions: insights into the colonisation of arid rangelands in Australia by the Eastern Grey Kangaroo (Macropus giganteus)

The Eastern Grey Kangaroo (Macropus giganteus) occurs mostly in the wetter regions of eastern Australia. However, in the past 30–40 years it has moved into more arid regions (rainfall<250 mm), thus increasing its overlap zone with the xeric adapted Red Kangaroo (Macropus rufus). An increased access to water (supplied for domestic stock) may explain this range extension, but changes in the availability of preferred feed could also be involved. The water use, drinking patterns and thermoregulatory behaviour of these two species of kangaroo have been examined in a semi-free range study, during summer at an arid rangeland site. Foraging was largely nocturnal in both species and during the day they behaved to reduce heat loads. This was especially so for M. giganteus, which showed greater shade seeking. However, it still used more water (72±2.6 mL kg⁻¹ day⁻¹, mean ± SE) than M. rufus (56±7.6 mL kg⁻¹ day⁻¹) and drank twice as frequently. Although M. giganteus produced a less concentrated urine (1422±36 mosmol kg⁻¹) than M. rufus (1843±28 mosmol kg⁻¹), kidney physiology did not explain all of the differences in water metabolism between the species. Water from the feed and faecal water retention also appear to be involved. Broadly, a better access to reliable water and the utilisation of mesic microhabitats has enabled M. giganteus to make inroads into the changing rangelands of eastern Australia. However, changes in the vegetation, due to stock grazing, have also favoured M. giganteus, which is a grass eating specialist.