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Biomedical subjects

A Cassone

Publications and source records attributed to A Cassone.

At least 181 records · Page 10Linked to original sources
PubMed1978

Effect of a tetracycline antibiotic on the experimental pathogenicity of Cryptococcus neoformans.

The pathogenicity of three stains of Cryptococcus neoformans was experimentally tested by intradermal inoculations into albino rabbits and intraperitoneally into mice. A relationship was found between the number of inoculated cells and the diameter of dermal lesion; moreover, a typical kinetics of lesion evolution and healing has been shown. Treatment of rabbits with deoxytetracycline did not dramatically influence the behavior of dermal lesions. However, in experiments dealing with strain Vi selected for its enhanced dermotropism, the antibiotic did significantly provoke a diminition of the inflammatory area. In mice, the antibiotic caused a marked increase in mortality (as evaluated by both LD50 values and rate of mortality). Neither in rabbits nor in mice, however, were we able to detect a significant effect of the drug on the dissemination of C. neoformans cells in internal organs. There is no simple explanation for the reported observations but it is possible that local factors in the derma or an aspecific antiinflammatory action of deoxytetracycline are responsible for the unusual response of dermal experimental infection to antibiotic treatment.

Animals↗
PubMed1977

The capsular network of Klebsiella pneumoniae.

Attempts at improving chemical fixation for electron-microscopic observation of the capsule of Klebsiella pneumoniae were made. The capsule was preserved by using alcian blue - lanthanum and tris-(1-aziridinyl) phosphine oxide (TAPO) - aldehyde - osmium procedures. Despite the different retention of the overall capsular material and minor variations in morphological details, in both cases the interpretation of ultrastructural patterns suggested that the capsule be composed of a meshed network of thin polysaccharide fibrils radiating from the cell wall. This organization is in keeping with all recognized chemical properties of bacterial polysaccharide capsules or, at least, does not contradict them. Moreover, an effective preservation of bacterial structures other than capsule has been obtained, mostly in specimens fixed by the TAPO-aldehyde-osmium method, a fact which gives further reliability to the technical approach used for capsule visualization.

Bacteriological Techniques↗
PubMed1975

Interaction of Sendai virus with human erythrocytes. III. Further investigation on the effects of pyridine on the virus envelope.

The ultrastructure of the pyridine-treated Sendai virus has further been investigated by electron microscopy of chemically fixed and negatively stained virions. Marked changes in the ultrastructural appearance of the viral envelope have been detected. The extent of these changes depends on pyridine dose and ranges from minor extraction of the outer track components to multiple breaks and disintegration of the whole envelope. At 16% pyridine a fragmentation of viral nucleocapsid has also been noted. Both the nature of these changes and the fact that even fully burst viral particles can eventually retain regularly-arranged spikes, strongly suggest that pyridine primarily affects the organization of the double-track viral membrane, probably by sequential extraction of lipids and protein components. The results are discussed in the light of the selective property of pyridine in discriminating among the biological activities of the Sendai virus and give additional support to the idea that phospholipids and a glycoprotein spike play cooperative roles in the hemolytic activity of the virus.

Dose-Response Relationship, Drug↗
PubMed1975

Presence of two virus-like particles in Penicillium citrinum.

Two icosahedral virus-like particles (28 and 19 nm in diameter, respectively) have been detected in sporogenic and asporogenic segregants of a strain of Penicillium citrinum. The distribution of the two particles differed among the two segregants.

Microscopy, Electron↗
PubMed1974

Inhibition of uridine transport in cultured mammalian cells by theophylline.

Theophylline (theobromine, caffeine) reversibly inhibits the incorporation of labeled RNA precursors both in confluent 37 RC and in exponentially growing HeLa cells. As measured in 37 RC after 2 h labeling, 20 mM theophylline reduces the incorporation of [3H]UTP and [14C]uridine into acid-precipitable material to 5% and 9% of the control, respectively. This reduction is paralleled by a comparably lowered incorporation of the same precursors into the acid-soluble pool. The initial rate of incorporation into total cell material is similarly affected by theophylline, the inhibition being of a simple competitive type. Theophylline does not alter the turnover rate of pulse labeled RNA during actinomycin D chase nor does it preclude the utilization of the endogenous pool of nucleoside phosphates. Upto a concentration of 10 mM, it does not inhibit uridine kinase neither in 37 RC nor in HeLa cells. The mentioned inhibitory effects of theophylline cannot be mimicked by exogenously added cyclic AMP. All the data support the conclusion that theophylline inhibits the transport of uridine into the cell.

Biological Transport↗
PubMedDate not supplied

Expression of the complement-binding protein (MP60) of Candida albicans in experimental vaginitis.

The expression of the Candida albicans complement-binding C3d protein (MP60) was investigated both in vitro and in vivo by immunogold labelling and electron microscopy. In vivo expression was determined in a rat vaginitis model. Reactivity of in vitro-grown cells to an anti-MP60 rabbit serum was associated with both cytoplasmic and cell wall sites. Immunostaining in the cell wall of both yeast and hyphae was most concentrated in the inner, electron-lucid layer. Immunogold stained preparations of C. albicans from vaginal smears of infected animals also showed intense localization of the MP60 in the inner cell wall, plasma membrane. However, immunogold label was also intense at the cell surface in these samples, mostly in the area of close adherence with the keratinocytes of the vaginal epithelia. These observations indicate that MP60 is expressed both in vitro and in vivo, but to a different degree in the different cell wall layers.

Animals↗