Comparison of the growth of virulent and attenuated strains of Candida albicans in the kidneys of normal and cortisone-treated mice by Chitin assay

Candida albicans strain 22114 was avirulent for mice compared with strain 19321 in that, administered intravenously, 10⁶ blastospores of 22114 failed to kill whereas 10⁶ blastospores of 19321 produced 100% mortality. Cortisone treatment rendered mice susceptible to killing by 22114. Chitin assay showed that cortisone stimulated the growth of both strains in the mouse kidney. Growth of 19321 was increased up to five-fold and 22114 up to forty-fold. The strains may have differential susceptibility to cortisone-sensitive host defences which control fungal growth in vivo.     

The effect of the fungal growth stimulants present in bovine placenta on experimental Absidia corymbifera infection in mice

Parenteral administration of bovine placental extract to mice in the period overlapping inoculation with spores of Absidia corymbifera did not increase their susceptibility to acute, lethal infection of the central nervous system. It did, however, exacerbate the chronic and sub-acute renal lesions which developed in those animals which survived inoculation without developing acute infection. This probably resulted from excretion by the kidneys of fungal growth stimulants derived from the placental extract.     

Growth hormone attenuates the brain damage caused by ZIKV infection in mice

As a member of vector-borne viruses, Zika virus (ZIKV) can cause microcephaly and various neurological symptoms in newborns. Previously, we found that ZIKV could infect hypothalamus, causing a decrease in growth hormone (GH) secretion, growth delay and deficits in learning and memory in suckling mice. Early administration of GH can improve the cognitive function of the mice. Therefore, in this study we further investigated the mechanism underlying the protective role of GH in ZIKV infection in suckling mice. Our results showed that GH could effectively reduce brain damage caused by ZIKV infection via reducing cell apoptosis and inflammatory response rather than inhibiting viral replication. Our results provide important evidences not only for understanding the mechanism underlying ZIKV-associated neurological symptoms but also for the treatment of ZIKV infection.     

Serodiagnosis of Mycoplasma pulmonis infection in mice and rats by an enzyme-linked immunosorbent assay

Murine antibody against Mycoplasma pulmonis (Mp) was detected sensitively and specifically in experimentally and naturally infected animals by an enzyme-linked immunosorbent assay (ELISA), using urease conjugated antimurine immunoglobulin. More than 98% of the experimentally infected mice and rats exhibited positive reaction in the ELISA two or more weeks after infection, and the titer remained for a prolonged period (up to one year) after infection. However, we failed to detect antibody in the sera of one-week-postinfected animals. Mice and rats from breeding colonies were tested with the ELISA and compared with isolation of Mp from the respiratory organs. Positive reactions were shown in the ELISA using the sera from 91% of the mice and 98% of the rats from which the organisms were isolated. Conversely, 97% of the mice and 78% of the rats among Mp-free animals showed negative results in the ELISA. The sensitivity and specificity of the complement fixation test, which has been used widely for serodiagnosis of Mp-infection, were apparently lower compared to those of the ELISA. From these results, the ELISA was found to be available for the serodiagnosis of Mp-infection in mice and rats.     

Germination of Aspergillus fumigatus conidia in the lungs of normal and cortisone-treated mice.

Inhaled conidia of Aspergillus fumigatus germinated in the lungs of mice at a low rate but both germinated and ungerminated spores were cleared. Spores germinated at a high rate in the lungs of cortisone-treated mice.     

The use of cortisone-treated mice in the screening of soil for pathogenic fungi

Summary Fifty-seven samples of desert soils were screened for pathogenic fungi by injection into cortisone-treated and non-treated mice. Four samples yielded pathogenic fungi in the cortisone-treated mice only.Nocardia asteroides was isolated from the cortisone-treated mice and from the controls. All of the cortisone-treated and the control mice injected with soil from the root zone of a dead century plant became critically ill very shortly after injection and cultures from all of the animals showed a variety of fungi. Seven species were isolated from the cortisone-treated animals and 5 species from the controls.The yeast,Torulopsis glabrata, was found in 69 of the 225 control mice and in 115 of the 213 cortisone-treated animals that came to autopsy. This organism was not considered to have been derived from the soil.The results appear to justify the conclusion that this method of soil screening deserves further consideration and study.     

Improved assay and mechanism of the reaction catalyzed by the chitin synthase from Saccharomyces cerevisiae

1. An improved filtration method is introduced to perform kinetic investigations on the chitin synthase reaction. This method is especially suited for the assay of a large number of samples necessary in enzyme kinetic studies. 2. From initial rate data the possibility could be excluded that the two-substrate reactions occurs by a random or a ping-pong mechanism. 3. Investigations of product inhibition exclude a rapid random mechanism but favour an ordered mechanism with UDP-N-acetylglucosamine as the first substrate. 4. This result was confirmed by isotope exchange studies.     

Estimation of mycelial growth of basidiomycetes by means of chitin determination

After hydrolysis of chitin in 6 M HCl, the glucosamine produced was assayed colorimetrically. The pH of the hydrolysate was adjusted to a value close to three by addition of Na acetate; this procedure avoids the elimination of excess acid by evaporation under reduced pressure or freeze-drying. Under these conditions, the amount of glucosamine determined by the assay represented an average of 90% of the amount which would result from a total hydrolysis of the chitin. The method was used to assay the chitin in the mycelia of basidomycetes obtained in vitro. The measured amount of glucosamine was proportional to the mycelial biomass and allowed the estimation of fungal growth.     

Vascular and tubular renin in the kidneys of mice

Summary Monospecific antisera and the immunocytochemical PAP-method have been used to localize renin in the kidneys of mice. With this procedure, reaction product was not only observed in the epitheloid cells of kidney vessels but also in kidney tubules: in the apical portion of proximal tubule cells and in some cells of the connecting and the cortical collecting tubule. To answer the question, whether the occurrence of renin in kidney tubule cells is the consequence of tubular synthesis or that of glomerular filtration of plasma renin followed by its uptake from the tubular lumen, tracer experiments with radioiodinated renin and with horseradish peroxidase were undertaken. The results of these studies as well as other arguments suggest reabsorptive pinocytosis of the filtered hormone as the source of tubular renin.These studies were supported by the Deutsche Forschungsgemeinschaft within the SFB 90 Cardiovasculäres System     

Candidal vaginitis in hormone-treated mice: Prevention by a chitin extract

In view of findings from previous studies that a chitin soluble extract (CSE) blocked adhesion of Candida albicans in vitro and in vivo and prevented thereby a short lived candidal infection in naive mice, we attempted in the present study to block by CSE the development of a persistent infection, induced in hormone-treated animals. Continuous oestrus phase was obtained in mice by repeated weekly subcutaneous injections with estradiol benzoate. Intravaginal inoculation of the hormone-treated mice with 10⁷–10¹⁰ C. albicans cells induced a persistent candidal infection. Fifty three mice were pretreated intravaginally prior to inoculation of C, albicans with 2.5, 5.0 or 10 mg/mouse of a CSE cream and followed up for development of infection in comparison to 30 untreated animals. Twenty four hrs post fungus inoculation the infection rate among the CSE treated mice was 11–23% VS 84% among the controls; the rate increased a week later to 97% among the controls VS 41–50% among the CSE treated. Administering the CSE to the mice prior — and post-yeast inoculation (37 mice), led to increased efficacy of the treatment. The data, indicating that CSE is an effective measure for preventing persistent candidal vaginitis, may open the way to consider a similar approach for prophylaxis of vaginitis in human susceptible populations.     

Parameters optimization of chitin hydrolysis by Trichoderma harzianum chitinase under assay conditions

A kinetic analysis and optimization of reaction conditions for the enzymatic hydrolysis of chitin using chitinase produced by Trichoderma harzianum NCIM 1185 was carried out. Swollen chitin was used as the substrate for chitinase. The central composite design was followed for this optimization. The required volume ratio of the major reactants for maximum hydrolysis was determined. The pH and temperature optima were found to be 4.75 and 47 °C respectively. K _m and V _max for this enzyme were 4.643 kg/m³ and 0.1542 U respectively.     

Selenium and mercury are redistributed to the brain during viral infection in mice

As part of the general host response to coxsackievirus B3 (CB3) infection, the concentration of essential and nonessential trace elements changes in different target organs of the infection. Essential (e.g., Se) and nonessential (e.g., Hg) trace elements are known to interact and affect inflammatory tissue lesions induced by CB3 infection. However, it is unknown whether these changes involve the brain. In the present study, the brain Hg and Se contents were measured through inductively coupled plasma-mass spectrometry and their distribution investigated by means of nuclear microscopy in the early phase (d 3) of CB3 infection in normally fed female Balb/c mice. Because of the infection, the concentration of Hg (4.07±0.46 ng/g wet wt) and Se (340±16 ng/g wet wt) in the brain increased twofold for Hg (8.77±1.65 ng/g wet wt, p<0.05) and by 36% for Se (461±150 ng/g wet wt, ns). Nuclear microscopy of brain sections from mice having elevated Se and Hg concentrations failed to find localized levels of the elements high enough to make detection possible, indicating approximately homogeneous tissue distribution. Although the pathophysiological interpretation of these findings requires further research, the increase of Hg in the brain during infection might have an influence on the pathogenesis of the disease.